Serratia

FEBS J, 2005 Jan, 272(2), 538 - 49
Degradation of chitosans with chitinase B from Serratia marcescens; Sorbotten A et al.; Family 18 chitinases such as chitinase B (ChiB) from Serratia marcescens catalyze glycoside hydrolysis via a mechanism involving the N-acetyl group of the sugar bound to the -1 subsite . We have studied the degradation of the soluble heteropolymer chitosan, to obtain further insight into catalysis in ChiB and to experimentally assess the proposed processive action of this enzyme . Degradation of chitosans with varying degrees of acetylation was monitored by following the size-distribution of oligomers, and oligomers were isolated and partly sequenced using (1)H-NMR spectroscopy . Degradation of a chitosan with 65% acetylated units showed that ChiB is an exo-enzyme which degrades the polymer chains from their nonreducing ends . The degradation showed biphasic kinetics: the faster phase is dominated by cleavage on the reducing side of two acetylated units (occupying subsites -2 and -1), while the slower kinetic phase reflects cleavage on the reducing side of a deacetylated and an acetylated unit (bound to subsites -2 and -1, respectively) . The enzyme did not show preferences with respect to acetylation of the sugar bound in the +1 subsite . Thus, the preference for an acetylated unit is absolute in the -1 subsite, whereas substrate specificity is less stringent in the -2 and +1 subsites . Consequently, even chitosans with low degrees of acetylation could be degraded by ChiB, permitting the production of mixtures of oligosaccharides with different size distributions and chemical composition . Initially, the degradation of the 65% acetylated chitosan almost exclusively yielded oligomers with even-numbered chain lengths . This provides experimental evidence for a processive mode of action, moving the sugar chain two residues at a time . The results show that nonproductive binding events are not necessarily followed by substrate release but rather by consecutive relocations of the sugar chain.

Biopolymers . 2005 Jan 6; {Epub ahead of print}
Development and application of a model for chitosan hydrolysis by a family 18 chitinase; Sikorski P et al.; Hydrolysis of partially deacetylated chitosans by ChitinaseB (ChiB) from Serratia marcescens results in mixtures of oligosaccharides typically between 2 and 20 sugar residues . The amounts of different oligomer fractions depend on the degree of acetylation of the starting chitosans . We have used experimentally determined distributions of hydrolysis products to develop a model for chitosan hydrolysis by ChiB . Important elements of the model include interaction parameters for acetylated/deacetylated units in each of the six subsites in the active cleft, and degree of processivity (multiple attack) . The hydrolysis reaction is described as a chemical reaction with an activation barrier that depends on the substrate sequence presented to the enzyme subsites . Using "Monte Carlo" approach, the interaction parameters were refined by minimising the difference between observed and predicted amounts of hydrolysis products obtained upon degradation of chitosan with a degree of acetylation of 65% . The final model can accurately predict complex patterns of oligosaccharides produced in the hydrolysis of chitosans with various degrees of acetylation, as well as patterns observed during reactions with chito-oligosaccharides . The behaviour of a ChiB mutant with a mutation in subsite +2 (Gly188Asp) which reduces affinity for an acetylated sugar, could be predicted correctly by introducing one single change in the model parameters (the interaction energy for an acetylated unit in +2 subsite) . The proposed model may be used to explore degradation products for different enzyme-substrates combinations and optimise conditions for preparation of specific oligosaccharides . In addition, the model provides insight into subsite interaction parameters and the degree of processivity, which complements previous experimental studies on the mode of action of ChiB . (c) 2005 Wiley Periodicals, Inc . Biopolymers, 2005.

Wilderness Environ Med, 2004 Winter, 15(4), 245 - 9
Coliform and pathologic bacteria in Sierra Nevada national forest wilderness area lakes and streams; Derlet RW et al.; OBJECTIVE: To analyze backcountry-area water quality in US Department of Agriculture Forest Service-designated wilderness areas for the presence of coliform and potentially pathogenic bacteria . METHODS: Thirty-one backcountry lakes and streams were selected that would stratify the risk based on use by backpackers, pack animals, commercial grazing animals, or natural unaffected wilderness areas . Sites included Desolation Wilderness (10 sites), Carson-Iceberg Wilderness (4 sites), Emigrant Wilderness (3 sites), Hoover Wilderness (6 sites), John Muir Wilderness (3 sites), and Golden Trout Wilderness (5 sites) . Water was collected in sterile tubes and quantification was performed through Millipore bacterial samplers . On return to the laboratory, bacteria were harvested from the samplers and subjected to qualitative analysis that identified species according to standard laboratory methods . RESULTS: Coliform bacteria were detected in 14 of 31 sites (45%) . Eight sites had high levels of coliforms . All 8 of these sites correlated with heavy human use or commercial grazing . Coliforms were identified as Escherichia coli . In addition, 1 sample contained Yersinia entercolitica . All samples contained expected amounts of normal aquatic bacteria, including Pseudomonas spp, Rahnella aquatilis, Serratia spp, and other nonpathogenic species of Yersinia in concentrations of 600 to 10,000 colony-forming units per 100 mL . CONCLUSIONS: In this study, coliform bacteria were found at nearly half of the sampling sites . High coliform levels correlated with high-impact human use or cattle grazing.

Wilderness Environ Med, 2004 Winter, 15(4), 238 - 44
An analysis of wilderness water in Kings Canyon, Sequoia, and Yosemite national parks for coliform and pathologic bacteria; Derlet RW et al.; OBJECTIVE: To determine the prevalence of coliform and potentially pathogenic bacteria in remote backcountry alpine lakes and streams of national parks in the Sierra Nevada mountains . METHODS: Water was sampled at 55 predetermined lakes and streams that would stratify the risk, based on sites used by backpackers, sites used by pack animals, and uncontaminated wild areas . Sites were distributed among Kings Canyon (15), Sequoia (17), and Yosemite (23) . Water was collected using Millipore bacterial samplers, which provided specific counts of coliform and other bacteria in each water sample and also served as a transport media from the wilderness to the laboratory . On return to the laboratory, bacteria were harvested from the samplers and subjected to specific identification and qualitative analysis using standard microbiology techniques for the analysis of water . RESULTS: Coliform bacteria were detected in 22 of the 55 sites . All of these sites were below areas used by backpackers or pack animals . Thirty-three sites were free of coliforms . These sites included both those used lightly by backpackers and those with no human or domestic animal use . All samples contained expected amounts of normal aquatic bacteria including Pseudomonas, Rahnella aquatilis, Serratia spp, and nonpathogenic species of Yersinia . CONCLUSIONS: Most sampling sites in these national parks are free of coliform or pathogenic organisms . Low levels of coliform bacteria are found in some bodies of water where the watershed has been affected by human or pack animal travel.

J Food Prot, 2004 Dec, 67(12), 2760 - 6
Performance comparison of the BioSys optical assay and the violet red bile agar method for detecting coliforms in food products; Firstenberg-Eden R et al.; Coliform counts in a variety of foods, including dairy products (raw milk, pasteurized milk, yogurt, butter, and ice cream), meats (pork sausage, ground beef, and raw chicken), raw eggs, and chocolate, were performed by the rapid automated BioSys optical assay and the conventional method with violet red bile agar (VRBA) . The standard deviation (SD) among five replicate counts for the optical assay was similar to or better than that obtained with VRBA plates for all foods tested . The average SD for all foods tested was 0.21 for the optical assay and 0.30 for the VRBA plates . At very low concentrations of coliforms (1 to 10 CFU/ml for liquid products and 10 to 100 CFU/g for solid samples), the average SDs were 0.26 and 0.47, respectively . The optical assay was less susceptible to interference by noncoliform organisms . In naturally contaminated samples, bacteria such as Serratia liquefaciens, Pantoea spp., Vibrio fluvialis, Aeromonas hydrophilia, and Pseudomonas spp . formed typical colonies in VRBA, resulting in false-positive results or a need to verify colonies in brilliant green lactose broth . The optical assay appeared to be more selective than the VRBA conventional method, detecting fewer noncoliforms . There was close agreement in test results between the two methods, as indicated by correlation coefficients of 0.92 to 0.99 obtained for the regression analysis of the two methods . In most cases both methods distinguished accurately between positive samples containing coliforms and negative controls . All products tested using the automated BioSys Optical Assay for coliforms yielded results more quickly (typically 10 to 12 h) than did those tested with the conventional VRBA method (24 to 72 h with confirmation).

Ocul Immunol Inflamm, 2004 Dec, 12(4), 287 - 95
Induction of cytokines from polymorphonuclear leukocytes and epithelial cells by ocular isolates of Serratia marcescens; Hume E et al.; Purpose: During contact lens wear, bacterial contamination of the lens can lead to the development of microbial keratitis (MK) or contact lens induced acute red eye (CLARE) . Inflammatory mediators released by the host may heighten the response . We have examined the ability of human corneal epithelial cells and polymorphonuclear leukocytes (PMNs) to release cytokines upon stimulation with bacteria . Methods: Serratia marcescens strains were added to corneal epithelial cells or PMNs . After incubations of up to 20 hours, supernatants were assayed for the presence of inflammatory mediators by ELISA . Results: All strains stimulated PMNs to release IL-8 and LTB(4) . Epithelial cells did not release LTB(4) . IL-8 was released after exposure to most S . marcescens isolates . A sub-group of strains stimulated the release of TNF-alpha from corneal epithelial cells . Conclusions: S . marcescens can stimulate the release of inflammatory mediators from both PMNs and corneal epithelial cells . This release could be important in the progression and resolution of MK and CLARE.

Biotechnol Lett, 2004 Nov, 26(22), 1723 - 1730
Synthesis of nanophase hydroxyapatite by a Serratia sp . from waste-water containing inorganic phosphate; Yong P et al.; Synthesis of nanophase hydroxyapatite (HA) on a bacterial surface was achieved at the expense of CaCl(2) and inorganic phosphate (Pi) . After initial nucleation, calcium was precipitated on and around the cells as calcium phosphate at the expense of inorganic phosphate in the challenge solution, with no precipitation in cell-free controls . HA was also biomanufactured using inorganic phosphate ions scavenged from a phosphate-containing waste-water . With additional Ca(2+), the concentration of phosphate was decreased from 0.27 ( approximately 25 ppm) to approximately 0.02m ( approximately 2 ppm) in the waste-water . Crystals of calcium phosphate manufactured by the cells were located by scanning electron microscopy (SEM) and identified as HA by X-ray powder diffraction, with an average crystal size calculated as approximately 25 nm . Possible application of bioHA as a biomaterial and implications for one-step `waste-into product' are discussed.

Biotechnol Lett, 2004 Nov, 26(21), 1643 - 8
Oxidation of heterocyclic and aromatic aldehydes to the corresponding carboxylic acids by Acetobacter and Serratia strains; Mitsukura K et al.; Conversion of heterocyclic and aromatic aldehydes to the corresponding carboxylic acids was carried out using Acetobacter rancens IFO3297, A . pasteurianus IFO13753 and Serratia liquefaciens LF14 . IFO3297 produced 110g 2-furoic acid l(-1) from furfural with a 95% molar yield . 5-Hydroxymethyl-2-furancarboxylic acid was produced from the corresponding aldehyde by using whole cells LF14 . IFO13753 and LF14 both converted isophthalaldehyde, 2,5-furandicarbaldehyde, 2,5-thiophenedicarbaldehyde and 2,2' biphenyldicarbaldehyde to the corresponding formylcarboxylic acid with 86--91% molar yields.

J Biol Chem . 2004 Dec 8; {Epub ahead of print}
Crystal structure and binding properties of the Serratia marcescens chitin-binding protein CBP21; Vaaje-Kolstad G et al.; Chitin proteins (CBPs) are commonly found in bacteria that utilize chitin as a source of energy . CBP21 is a chitin binding protein from Serratia marcescens, a Gram-negative soil bacterium capable of efficient chitin degradation . When grown on chitin, Serratia marcescens secretes large amounts of CBP21, along with chitin degrading enzymes . In an attempt to understand the molecular mechanism of CBP21 action, we have determined its crystal structure at 1.55 A resolution . This is the first structure of a family 33 carbohydrate binding module to be solved . The structure reveals a "budded" fibronectin type III fold, consisting of two b-sheets, arranged as a b-sheet sandwich, with a 65-residue "bud", consisting of three short helices, located between b-strands 1 and 2 . Remarkably, conserved aromatic residues that have previously been suggested to play a role in chitin binding were mainly found in the interior of the protein, seemingly incapable of interacting with chitin, whereas the structure reveals a surface patch of highly conserved, mainly hydrophilic residues . The roles of six of these conserved surface-exposed residues (Tyr54, Glu55, Glu60, His114, Asp182, Asn185) were probed by site-directed mutagenesis and subsequent binding studies . All single point mutations lowered the affinity of CBP21 for b-chitin, as shown by three- to eight-fold increases in the apparent binding constant . Thus, binding of CBP21 to chitin seems to be mediated primarily by conserved, solvent exposed, polar side chains.

J Biol Chem . 2004 Dec 2; {Epub ahead of print}
Novel, anion-independent iron coordination by members of a third class of bacterial periplasmic Ferric Ion-binding proteins; Shouldice SR et al.; The uptake of the element iron is vital for the survival of most organisms . Numerous pathogenic Gram-negative bacteria utilize a periplasm-to-cytosol ATP-binding cassette transport pathway in order to transport this essential atom in to the cell . In this study, we investigated the Yersinia enterocolitica (YfuA) and Serratia marcescens (SfuA) iron-binding periplasmic proteins . We have determined the 1.8-A structures of iron-loaded (YfuA) and iron-free (SfuA) forms of this class of proteins . Although the sequence of these proteins varies considerably from the other members of the transferrin structural superfamily, they adopt the same three-dimensional fold . The iron-loaded YfuA structure illustrates the unique nature of this new class of proteins in that they are able to octahedrally coordinate the ferric ion in the absence of a bound anion . The iron-free SfuA structure contains a bound citrate anion in the iron-binding cleft that tethers the N- and C-terminal domains of the apo protein and stabilizes the partially open structure.

Biol Chem, 2004 Nov, 385(11), 1007 - 16
Role of bacterial proteases in pseudomonal and serratial keratitis; Matsumoto K; Pseudomonas aeruginosa and Serratia marcescens can cause refractory keratitis resulting in corneal perforation and blindness . These bacteria produce various kinds of proteases . In addition to pseudomonal elastase (LasB) and alkaline protease, LasA protease and protease IV have recently been found to be more important virulence factors of P . aeruginosa . S . marcescens produces a cysteine protease in addition to metalloproteases . These bacterial proteases have a number of biological activities, such as degradation of tissue constituents and host defense-oriented proteins, as well as activation of zymogens (Hageman factor, prekallikrein and pro-matrix metalloproteinases) through limited proteolysis . In this article, the properties of these bacterial proteases are reviewed and the pathogenic roles of these proteases in pseudomonal keratitis are discussed.

Nucleic Acids Res, 2004, 32(20), 6129 - 35 Print 2004.
Type II restriction endonuclease R.KpnI is a member of the HNH nuclease superfamily; Saravanan M et al.; The restriction endonuclease (REase) R.KpnI is an orthodox Type IIP enzyme, which binds to DNA in the absence of metal ions and cleaves the DNA sequence 5'-GGTAC--C-3' in the presence of Mg2+ as shown generating 3' four base overhangs . Bioinformatics analysis reveals that R.KpnI contains a betabetaalpha-Me-finger fold, which is characteristic of many HNH-superfamily endonucleases, including homing endonuclease I-HmuI, structure-specific T4 endonuclease VII, colicin E9, sequence non-specific Serratia nuclease and sequence-specific homing endonuclease I-PpoI . According to our homology model of R.KpnI, D148, H149 and Q175 correspond to the critical D, H and N or H residues of the HNH nucleases . Substitutions of these three conserved residues lead to the loss of the DNA cleavage activity by R.KpnI, confirming their importance . The mutant Q175E fails to bind DNA at the standard conditions, although the DNA binding and cleavage can be rescued at pH 6.0, indicating a role for Q175 in DNA binding and cleavage . Our study provides the first experimental evidence for a Type IIP REase that does not belong to the PD...D/EXK superfamily of nucleases, instead is a member of the HNH superfamily.

Braz J Med Biol Res, 2004 Dec, 37(12), 1763 - 9 Epub 2004 Dec.
A role for histone-like protein H1 (H-NS) in the regulation of hemolysin expression by Serratia marcescens; Franzon JH et al.; The histone-like protein H1 (H-NS) is an abundant structural component of the bacterial nucleoid and influences many cellular processes including recombination, transcription and transposition . Mutations in the hns gene encoding H-NS are highly pleiotropic, affecting the expression of many unrelated genes . We have studied the role of H-NS on the regulation of hemolysin gene expression in Serratia marcescens . The Escherichia coli hns mutant carrying S . marcescens hemolysin genes on a plasmid constructed by ligation of the 3.2-kb HindIII-SacI fragment of pR02 into pBluescriptIIKS, showed a high level of expression of this hemolytic factor . To determine the osmoregulation of wild-type and hns defective mutants the cells were grown to mid-logarithmic phase in LB medium with 0.06 or 0.3 M NaCl containing ampicillin and kanamycin, whereas to analyze the effect of pH on hemolysin expression, the cells were grown to late-logarithmic phase in LB medium buffered with 0.1 M Tris-HCl, pH 4.5 to 8.0 . To assay growth phase-related hemolysin production, bacterial cells were grown in LB medium supplemented with ampicillin and kanamycin . The expression of S . marcescens hemolysin genes in wild-type E . coli and in an hns-defective derivative at different pH and during different growth phases indicated that, in the absence of H-NS, the expression of hemolysin did not vary with pH changes or growth phases . Furthermore, the data suggest that H-NS may play an important role in the regulation of hemolysin expression in S . marcescens and its effect may be due to changes in DNA topology influencing transcription and thus the amount of hemolysin expression . Implications for the mechanism by which H-NS influences gene expression are discussed.

BMC Evol Biol . 2004 Nov 22;4(1):49.
Diversity and specificity in the interaction between Caenorhabditis elegans and the pathogen Serratia marcescens; Schulenburg H et al.; BACKGROUND: Co-evolutionary arms races between parasites and hosts are considered to be of immense importance in the evolution of living organisms, potentially leading to highly dynamic life-history changes . The outcome of such arms races is in many cases thought to be determined by frequency dependent selection, which relies on genetic variation in host susceptibility and parasite virulence, and also genotype-specific interactions between host and parasite . Empirical evidence for these two prerequisites is scarce, however, especially for invertebrate hosts . We addressed this topic by analysing the interaction between natural isolates of the soil nematode Caenorhabditis elegans and the pathogenic soil bacterium Serratia marcescens . RESULTS: Our analysis reveals the presence of i) significant variation in host susceptibility, ii) significant variation in pathogen virulence, and iii) significant strain- and genotype-specific interactions between the two species . CONCLUSIONS: The results obtained support the previous notion that highly specific interactions between parasites and animal hosts are generally widespread . At least for C . elegans, the high specificity is observed among isolates from the same population, such that it may provide a basis for and/or represent the outcome of co-evolutionary adaptations under natural conditions . Since both C . elegans and S . marcescens permit comprehensive molecular analyses, these two species provide a promising model system for inference of the molecular basis of such highly specific interactions, which are as yet unexplored in invertebrate hosts.

J Ind Microbiol Biotechnol . 2004 Nov 11; {Epub ahead of print}
Optimization of Serratia marcescens lipase production for enantioselective hydrolysis of 3-phenylglycidic acid ester; Gao L et al.; Lipase production and cell growth of Serratia marcescens ECU1010 were optimized in shake flasks, with lipase production being enhanced 9.5-fold (4,780 U/l) compared with the initial activity (500 U/l) . Optimal carbon and nitrogen sources were Tween-80 and peptone, and the optimal ratio of Tween-80 to peptone was 1:3 . The optimized cultivation conditions were 25 degrees C and pH 6.5 . Lipase activity, particularly specific activity, could be improved by decreasing the cultivation temperature from 35 to 25 degrees C . Enzyme stability was significantly improved by simple immobilization with synthetic adsorption resin no . 8244 . After five reaction cycles, enzyme activity decreased only very slightly, while enantioselectivity of the preparation remained constant, and the ee(s) (enantiomeric excess of the remaining substrate) achieved in all cases was higher than 97% . The resin-8244-lipase preparation can be used for efficient enantioselective hydrolysis of trans-3-(4'-methoxyphenyl)glycidic acid methyl ester {(+/-)-MPGM}, a key intermediate in the synthesis of Diltiazem.

Vet Res, 2004 Nov-Dec, 35(6), 681 - 700
Innate immune response to intramammary infection with Serratia marcescens and Streptococcus uberis; Bannerman DD et al.; Streptococcus uberis and Serratia marcescens are Gram-positive and Gram-negative bacteria, respectively, that induce clinical mastitis . Once initial host barrier systems have been breached by these pathogens, the innate immune system provides the next level of defense against these infectious agents . The innate immune response is characterized by the induction of pro-inflammatory cytokines, as well as increases in other accessory proteins that facilitate host recognition and elimination of the pathogens . The objective of the current study was to characterize the innate immune response during clinical mastitis elicited by these two important, yet less well-studied, Gram-positive and Gram-negative organisms . The pro-inflammatory cytokine response and changes in the levels of the innate immune accessory recognition proteins, soluble CD14 (sCD14) and lipopolysaccharide (LPS)-binding protein (LBP), were studied . Decreased milk output, induction of a febrile response, and increased acute phase synthesis of LBP were all characteristic of the systemic response to intramammary infection with either organism . Infection with either bacteria similarly resulted in increased milk levels of IL-1 beta, IL-8, IL-10, IL-12, IFN-gamma, TNF-alpha, sCD14, LBP, and the complement component, C5a . However, the duration of and/or maximal changes in the increased levels of these inflammatory markers were significantly different for several of the inflammatory parameters assayed . In particular, S . uberis infection was characterized by the sustained elevation of higher milk levels of IL-1 beta, IL-10, IL-12, IFN-gamma, and C5a, relative to S . marcescens infection . Together, these data demonstrate the variability of the innate immune response to two distinct mastitis pathogens.

Pediatr Cardiol, 2004 Sep-Oct, 25(5), 562 - 4 Epub 2004 Jun 08.
Aspirin treatment for neonatal infectious endocarditis; Adler A et al.; We describe a term female neonate with Serratia marcescens endocarditis . Despite adequate antibiotic therapy for 8 days, the bacteremia persisted and there was an increase in vegetation size . Treatment with aspirin was initiated, with resolution of the bacteremia and a gradual decrease in vegetation size . We conclude that in neonatal endocarditis, aspirin may be beneficial additional treatment.

Org Biomol Chem, 2004 Nov 21, 2(22), 3329 - 36 Epub 2004 Oct 13.
Synthesis and stability of small molecule probes for Pseudomonas aeruginosa quorum sensing modulation; Glansdorp FG et al.; The human pathogen Pseudomonas aeruginosa uses N-butyryl-L-homoserine lactone (BHL) and N-(3-oxododecanyl)-L-homoserine lactone (OdDHL) as small molecule intercellular signals in a phenomenon known as quorum sensing (QS) . QS modulators are effective at attenuating P . aeruginosa virulence; therefore, they are a potential new class of antibacterial agent . The lactone in BHL and OdDHL is hydrolysed under physiological conditions . The hydrolysis proceeds at a rate faster than racemisation of the alpha-chiral centre . Non-hydrolysable, non-racemic analogues (small molecule probes) were designed and synthesised, replacing the lactone with a ketone . OdDHL analogues were found to be relatively unstable to decomposition unless they were difluorinated between the beta-keto amide . Stability studies on a non-hydrolysable, cyclohexanone analogue indicated that racemisation of the alpha-chiral centre was relatively slow . This analogue was assayed to show that the L-isomer is likely to be responsible for the QS autoinducing activity in P . aeruginosa and Serratia strain ATCC39006.

Microbiology, 2004 Nov, 150(Pt 11), 3547 - 60
The Serratia gene cluster encoding biosynthesis of the red antibiotic, prodigiosin, shows species- and strain-dependent genome context variation; Harris AK et al.; The prodigiosin biosynthesis gene cluster (pig cluster) from two strains of Serratia (S . marcescens ATCC 274 and Serratia sp . ATCC 39006) has been cloned, sequenced and expressed in heterologous hosts . Sequence analysis of the respective pig clusters revealed 14 ORFs in S . marcescens ATCC 274 and 15 ORFs in Serratia sp . ATCC 39006 . In each Serratia species, predicted gene products showed similarity to polyketide synthases (PKSs), non-ribosomal peptide synthases (NRPSs) and the Red proteins of Streptomyces coelicolor A3(2) . Comparisons between the two Serratia pig clusters and the red cluster from Str . coelicolor A3(2) revealed some important differences . A modified scheme for the biosynthesis of prodigiosin, based on the pathway recently suggested for the synthesis of undecylprodigiosin, is proposed . The distribution of the pig cluster within several Serratia sp . isolates is demonstrated and the presence of cryptic clusters in some strains shown . The pig cluster of Serratia marcescens ATCC 274 is flanked by cueR and copA homologues and this configuration is demonstrated in several S . marcescens strains, whilst these genes are contiguous in strains lacking the pig cluster.

Plasmid, 2004 Nov, 52(3), 182 - 202
The complete nucleotide sequence of the resistance plasmid R478: defining the backbone components of incompatibility group H conjugative plasmids through comparative genomics; Gilmour MW et al.; Horizontal transfer of resistance determinants amongst bacteria can be achieved by conjugative plasmid DNA elements . We have determined the complete 274,762 bp sequence of the incompatibility group H (IncH) plasmid R478, originally isolated from the Gram negative opportunistic pathogen Serratia marcescens . This self-transferable extrachromosomal genetic element contains 295 predicted genes, of which 144 are highly similar to coding sequences of IncH plasmids R27 and pHCM1 . The regions of similarity among these three IncH plasmids principally encode core plasmid determinants (i.e., replication, partitioning and stability, and conjugative transfer) and we conducted a comparative analysis to define the minimal IncHI plasmid backbone determinants . No resistance determinants are included in the backbone and most of the sequences unique to R478 were contained in a large contiguous region between the two transfer regions . These findings indicate that plasmid evolution occurs through gene acquisition/loss predominantly in regions outside of the core determinants . Furthermore, a modular evolution for R478 was signified by the presence of gene neighbors or operons that were highly related to sequences from a wide range of chromosomal, transposon, and plasmid elements . The conjugative transfer regions are most similar to sequences encoded on SXT, Rts1, pCAR1, R391, and pRS241d . The dual partitioning modules encoded on R478 resemble numerous sequences; including pMT1, pCTX-M3, pCP301, P1, P7, and pB171 . R478 also codes for resistance to tetracycline (Tn10), chloramphenicol (cat), kanamycin (aphA), mercury (similar to Tn21), silver (similar to pMG101), copper (similar to pRJ1004), arsenic (similar to pYV), and tellurite (two separate regions similar to IncHI2 ter determinants and IncP kla determinants) . Other R478-encoded sequences are related to Tn7, IS26, tus, mucAB, and hok, where the latter is surrounded by insLKJ, and could potentially be involved in post-segregation killing . The similarity to a diverse set of bacterial sequences highlights the ability of horizontally transferable DNA elements to acquire and disseminate genetic traits through the bacterial gene pool.

J Med Chem, 2004 Nov 4, 47(23), 5713 - 20
Structure-based exploration of cyclic dipeptide chitinase inhibitors; Houston DR et al.; Family 18 chitinases play an essential role in a range of pathogens and pests . Several inhibitors are known, including the potent inhibitors argadin and allosamidin, and the structures of these in complex with chitinases have been elucidated . Recent structural analysis has revealed that CI-4 {cyclo-(L-Arg-D-Pro)} inhibits family 18 chitinases by mimicking the structure of the proposed reaction intermediate . Here we report the high-resolution structures of four new CI-4 derivatives, cyclo-(L-Arg-L-Pro), cyclo-(Gly-L-Pro), cyclo-(L-His-L-Pro), and cyclo-(L-Tyr-L-Pro), in complex with a family 18 chitinase . In addition, details of enzyme inhibition and in vivo activity against Saccharomyces cerevisiae are presented . The structures reveal that the common cyclo-(Gly-Pro) substructure is sufficient for binding, allowing modification of the side chain of the nonproline residue . This suggests that design of cyclic dipeptides with a view to increasing inhibition of family 18 chitinases should be possible through relatively accessible chemistry . The derivatives presented here in complex with chitinase B from Serratia marcescens provide further insight into the mechanism of inhibition of chitinases by cyclic dipeptides as well as providing a new scaffold for chitinase inhibitor design.

Jpn J Infect Dis, 2004 Oct, 57(5), 189 - 92
A nosocomial outbreak of febrile bloodstream infection caused by heparinized-saline contaminated with Serratia marcescens, Tokyo, 2002; Tanaka T et al.; In January 2002, 12 patients with Serratia marcescens bloodstream infection (BSI) were identified in a hospital in Tokyo, Japan . We conducted an epidemiological investigation of this outbreak . We undertook a medical-records review and employee interviews, and performed a case-control study to determine risk factors for S . marcescens BSI . An observational study of the hospital's procedures and an environmental microbiologic sampling were performed . We identified 12 suspected and 12 confirmed patients with S . marcescens BSI, including 7 who died . A case-control study showed that vascular access devices (odds ratio {OR} = 30.46; 95% confidence interval {CI} = 3.5-685.6) and the use of heparin-locks, between December 26 and January 15 (OR = 25.7; 95% CI = 2.3-680.4) were significant risk factors for S . marcescens BSI . The observational study revealed multiple lapses in infection control, including use of multi-dose vials of heparin . The outbreak strain was isolated from a hand-towel in the nurse station . The use of multi-dose vials of heparinized-saline during a particularly busy period was associated with BSI risk . The results underscore the risks inherent in infection-control lapses and the use of multi-dose vials.

Microbiol Immunol, 2004, 48(10), 723 - 8
Identification and characterization of the pswP gene required for the parallel production of prodigiosin and serrawettin W1 in Serratia marcescens; Sunaga S et al.; Serratia marcescens mutants defective in production of the red pigment prodigiosin and the biosurfactant serrawettin W1 in parallel were isolated by transposon mutagenesis of strain 274 . Cloning of the DNA fragment required for production of these secondary metabolites with different chemical structures pointed out a novel open reading frame (ORF) named pswP . The putative product PswP (230 aa) has the distinct signature sequence consensus among members of phosphopantetheinyl transferase (PPTase) which phosphopantetheinylates peptidyl carrier protein (PCP) mostly integrated in the nonribosomal peptide synthetases (NRPSs) system . Since serrawettin W1 belongs to the cyclodepsipeptides, which are biosynthesized through the NRPSs system, and one pyrrole ring in prodigiosin has been reported as a derivative of L -proline tethered to phosphopantetheinylated PCP, the mutation in the single gene pswP seems responsible for parallel failure in production of prodigiosin and serrawettin W1.

Toxicon, 2004 Nov, 44(6), 641 - 7
Two novel species of tetrodotoxin-producing bacteria isolated from toxic marine puffer fishes; Yu CF et al.; Out of eight dominant discrete bacterial colonies isolated and purified from the toxic marine puffer fishes collected in Hong Kong waters, two novel species of non-sporing, non-acid-fast and chemoorganotrophic bacteria capable of producing tetrodotoxin (TTX, a potent non-protein neurotoxin), as well as one previously reported and confirmed TTX-producing bacterium . They were identified as Microbacterium arabinogalactanolyticum, Serratia marcescens and Vibrio alginolyticus, respectively, all of which are widely distributed in soils, sewage or marine environments . Each bacterial isolate (500 ml broth medium cultured in darkness without aeration for 10 days at 25 degrees C) could produce an amount of toxicity, after extraction and purification, ranging from 78.3 to 105.3 mouse units (MU) in 500 ml of broth medium by mouse bioassay . The principal toxic component in the bacterial cultures was determined to be TTX by thin layer chromatography and mass spectrometry.

J Biochem (Tokyo), 2004 Aug, 136(2), 163 - 8
Importance of exposed aromatic residues in chitinase B from Serratia marcescens 2170 for crystalline chitin hydrolysis; Katouno F et al.; Chitinase B (ChiB) of S . marcescens has five exposed aromatic residues linearly aligned toward the catalytic cleft, Tyr481 and Trp479 in the C-terminal domain, and Trp252, Tyr240 and Phe190 in the catalytic domain . To determine the contribution of these residues to the hydrolysis of crystalline beta-chitin, site-directed mutagenesis, to replace them by alanine, was carried out . The Y481A, W479A, W252A, and Y240A mutations all decreased the binding activity and hydrolyzing activity toward beta-chitin microfibrils . Substitution of Trp residues affected the binding activity more severely than that of Tyr residues . The F190A mutation decreased neither the binding activity nor the hydrolyzing activity . None of the mutations decreased the hydrolyzing activity toward soluble substrates . These results suggest that ChiB hydrolyzes crystalline beta-chitin via a mechanism in which four exposed aromatic residues play important roles, similar to the mechanism of hydrolysis by ChiA of this bacterium, although the directions of hydrolysis of the two chitinases are opposite.

Infect Control Hosp Epidemiol, 2004 Sep, 25(9), 730 - 4
Rapid eradication of a cluster of Serratia marcescens in a neonatal intensive care unit: use of epidemiologic chromosome profiling by pulsed-field gel electrophoresis; Lai KK et al.; OBJECTIVE: To investigate a cluster of patients infected and colonized with Serratia marcescens in a neonatal intensive care unit (NICU) . METHODS: In June 2001, two neonates in the NICU had clinical infections with S . marcescens and one died . Infection control surveillance data for the NICU revealed that S . marcescens was rarely isolated from clinical specimens . Surveillance and environmental cultures were performed and isolates were typed using pulsed-field gel electrophoresis . Staff and neonates were cohorted and a waterless, alcohol-based handwashing agent was introduced . A case-control study was performed . RESULTS: From June 2 through August 20, 2001, 11 neonates with S . marcescens infection and colonization were identified . The incidence of S . marcescens infections increased from 0.19 per 1,000 patient-days in 2000 to 0.52 per 1,000 patient-days in 2001 (P < .0001) . In the first 3 weeks of the investigation, there were 2 sets of patients and sinks with indistinguishable strains; however, in subsequent weeks, all isolates were of unique strains, signifying no further transmission of the two initial predominant strains . Neonates with S . marcescens were more likely to have a lower gestational age and birth weight . There was no association between cases and healthcare workers (HCWs) . CONCLUSIONS: A cluster of S . marcescens was quickly terminated after the introduction of preventive measures including cohorting of infected and colonized neonates and HCWs, contact precautions, surveillance cultures, and a waterless, alcohol-based hand antiseptic . Chromosomal typing determined that strains with an indistinguishable pattern were no longer present in the unit after control measures were implemented.

Infect Control Hosp Epidemiol, 2004 Sep, 25(9), 723 - 9
Clustering of Serratia marcescens infections in a neonatal intensive care unit; Sarvikivi E et al.; OBJECTIVES: To study clusters of infections caused by Serratia marcescens in a neonatal intensive care unit (NICU) and to determine risk factors for S . marcescens infection or colonization . DESIGN: Genotyping of S . marcescens isolates was performed by pulsed-field gel electrophoresis (PFGE) . A retrospective case-control study was conducted . SETTING: A tertiary-care pediatric hospital with a 16-bed NICU . PATIENTS: All neonates with at least one culture positive for S . marcescens in the NICU during December 1999 to July 2002 . Case-patients (n = 11) treated in the NICU during December 1999 to February 2000 were included in the case-control study . Neonates treated in the NICU for at least 72 hours during the same period with cultures negative for S . marcescens were used as control-patients (n = 27) . RESULTS: S . marcescens was cultured from 19 neonates; 9 were infected and 10 were colonized . PFGE analysis identified three epidemic strains; each cluster consisted of identical isolates, except one isolate in the first cluster that was different . The risk factors identified were low birth weight, prematurity, prolonged respiratory therapy, prolonged use of antibiotics, and maternal infection prior to delivery . Overcrowding and understaffing were recorded simultaneously with the clusters . CONCLUSIONS: PFGE analysis showed three independent clusters . Several factors contributed to spread of the epidemic strains: (1) there were many severely premature and susceptible neonates, (2) the NICU was overcrowded during the clusters, and (3) transmission was likely to occur via the hands of staff . Cohorting and improvement of routine infection control measures led to the cessation of each cluster.

J Am Vet Med Assoc, 2004 Sep 1, 225(5), 717 - 21
Evaluation of early fetal loss induced by gavage with eastern tent caterpillars in pregnant mares; Bernard WV et al.; OBJECTIVE: To determine whether gavage of pregnant mares (housed without access to pasture) with starved eastern tent caterpillars (ETCs) or their excreta is associated with early fetal loss (EFL), panophthalmitis, or pericarditis . DESIGN: Randomized clinical trial . ANIMALS: 15 mares . PROCEDURE: 15 mares with fetuses from 40 to 80 days of gestation (dGa) were randomly assigned to 1 of 3 groups and received 2.5 g of ETC excreta, 50 g of starved ETCs, or 500 mL of water, respectively, once daily for 10 days . Mares were housed in box stalls, walked twice daily, and not allowed access to pasture for 12 days before or during the 21-day trial . RESULTS: 4 of 5 mares gavaged with starved ETCs (group 2) aborted on trial days 8 (2 mares), 10, and 13 . No control mares or mares that received excreta aborted . Differences between the ETC group and other groups were significant . Abortion occurred on 49, 64, 70, and 96 dGa . Allantoic fluids became hyperechoic the day before or the day of fetal death . Alpha streptococci were recovered from 1 fetus and Serratia marcescens from 3 fetuses . Neither panophthalmitis nor pericarditis was seen . The abortifacient component of the ETCs was not elucidated . CONCLUSIONS AND CLINICAL RELEVANCE: These findings suggest that mares with fetuses from 40 to 120 days of gestation should not be exposed to ETCs because they may induce abortion.

Biophys Chem, 2004 Sep 1, 111(1), 1 - 7
Preliminary studies of the 2D crystallization of Omp1 of Serratia marcescens: observation by atomic force microscopy in native membranes environment and reconstituted in proteolipid sheets; Ruiz N et al.; In this work the porin Omp1 of Serratia marcescens was expressed in a porin deficient mutant (Escherichia coli UH302) and its functionality studied following the accumulation of ciprofloxacin in bacteria . The protein was extracted, purified and reconstituted in proteoliposomes of different composition (lipopolysaccharide (LPS), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and, 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)) . Maximum extraction of the detergent was achieved applying different steps of dialysis and centrifugation . Proteolipid sheets with different composition were spread onto mica and observed by atomic force microscopy . Two-dimensional crystal of Omp1 was not observed in any case due to low resolution achieved . Judging from the images features POPC is the most suitable phospholipid to enhance 2D lattice formation for Omp1.

Insect Biochem Mol Biol, 2004 Sep, 34(9), 893 - 901
Plasmodium berghei ookinetes induce nitric oxide production in Anopheles pseudopunctipennis midguts cultured in vitro; Herrera-Ortiz A et al.; The Anopheles pseudopunctipennis nitric oxide synthase gene (ApNOS) was identified and its partial sequence showed high homology with NOS from A . stephensi, A . gambiae (putative sequence), and Drosophila melanogaster . ApNOS was mainly expressed in male and female adult mosquitoes and was induced by a blood meal . Nitric oxide (NO) was produced by in vitro-cultured mosquito midguts inoculated by enema with Plasmodium berghei ookinetes, Saccharomyces cerevisiae, Gram-positive bacteria (Micrococcus luteus), but not with Gram-negative bacteria (Klebsiella pneumoniae, Escherichia coli or Serratia marcescens) . Dihydroxyphenylalanine (L-DOPA) oxidation induced the generation of NO in midguts in vitro, and hydrogen peroxide generated during its oxidation induced ApNOS expression . P . berghei ookinetes exposed in vitro to L-DOPA and sodium nitroprusside (a NO generator) were killed . These observations demonstrate that reactive oxygen and nitrogen intermediates constitute a part of the cytotoxic arsenal employed by Anopheles mosquitoes against microbial pathogens and Plasmodium ookinetes .

Appl Microbiol Biotechnol, 2005 Feb, 66(5), 512 - 9 Epub 2004 Sep 03.
Chemo-enzymatic synthesis of 2'-O-methoxyethyl ribonucleosides using a phosphodiesterase from Serratia marcescens; Marais G et al.; An enzyme able to cleave the 3',5'-phosphate ring of 2'-methoxyethyl cyclic nucleotides (3',5'-cyclic nucleotide phosphodiesterase, EC 3.1.4.17) from Serratia marcescens DSM 30121 was used to deprotect the cyclic phosphate nucleotides after chemical alkylation . The process yielded 2'-O-alkylated nucleosides used as building blocks of antisense oligonucleotides for subsequent potential applications in therapeutics (antisense oligonucleotide synthesis) and diagnostics . The phosphodiesterase from the Gram-negative enteric bacterium S . marcescens was selected on account of the broad substrate range and high activity of the enzyme . The protein was purified by heat-treatment of the crude cell-free extract, followed by column chromatography (gel filtration) . It was characterised and showed optimal activity at a broad pH range (pH 6.8-9.4, with a peak at ca . pH 8.5) and at a temperature of 60-65 degrees C . No metal ions were required for activity, although Ba(2+) was an activator . Conversion of 2'-O-methoxyethyl cAMP into the corresponding nucleoside derivative on a multi-gram scale was successfully performed in two steps, using the S . marcescens enzyme in conjunction with a commercially available alkaline phosphatase from Escherichia coli.

Biochem Pharmacol, 2004 Oct 1, 68(7), 1345 - 52
Mitochondria-mediated apoptosis operating irrespective of multidrug resistance in breast cancer cells by the anticancer agent prodigiosin; Soto-Cerrato V et al.; Prodigiosin (PG) is a red pigment produced by Serratia marcescens with pro-apoptotic activity in haematopoietic and gastrointestinal cancer cell lines, but no marked toxicity in non-malignant cells . Breast cancer is the most frequent malignancy among women in the European Union and better therapies are needed, especially for metastatic tumors . Moreover, multidrug resistance is a common phenomenon that appears during chemotherapy, necessitating more aggressive treatment as prognosis worsens . In this work, we extend our experiments on PG-induced apoptosis to breast cancer cells . PG was potently cytotoxic in both estrogen receptor positive (MCF-7) and negative (MDA-MB-231) breast cancer cell lines . Cytochrome c release, activation of caspases-9, -8 and -7 and cleavage of poly (ADP-ribose) polymerase protein typified the apoptotic event and caspase inhibition revealed that PG acts via the mitochondrial pathway . In a multidrug-resistant subline of MCF-7 cells that over-expresses the breast cancer resistance protein, the cytotoxic activity of PG was slightly reduced . However, flow-cytometry analysis of PG accumulation and efflux in MCF-7 sublines showed that PG is not a substrate for this resistance protein . These results suggest that PG is an interesting and potent new pro-apoptotic agent for the treatment of breast cancer even when multidrug resistance transporter molecules are present.

Mol Microbiol, 2004 Aug, 53(4), 1267 - 77
Haemophore-mediated signalling in Serratia marcescens: a new mode of regulation for an extra cytoplasmic function (ECF) sigma factor involved in haem acquisition; Biville F et al.; Bacterial extra cytoplasmic function (ECF) sigma factors control a wide range of cell envelope activities including iron and haem uptake systems . Sigma activity is usually inhibited by membrane-bound antisigma . An extra cytoplasmic signal modulates sigma-antisigma interactions and thereby leads to the transcription of the target operon . Sigma and antisigma genes generally belong to one autoregulated operon . However, ECF sigma and antisigma genes involved in iron acquisition, also called iron starvation ECF, are non-autoregulated exceptions to this rule . We fully reconstituted the has signalling cascade of Serratia marcescens in Escherichia coli . Binding of the haem-loaded haemophore to the outer membrane receptor, HasR, inactivates the antisigma HasS, turning on HasI and thereby allowing has operon transcription . Deletion of the HasR N-terminal extension, present in all characterized outer membrane receptors endowed with signal transduction capacity, abolished the inducing activity but not the transport activity . Induction required the TonB-ExbB-ExbD complex . HasI, like the other iron starvation sigma, is iron repressed but not autoregulated . We found an entirely new regulation for the antisigma hasS gene, the transcription of which is HasI dependent . We suggest that the has system is both activated and repressed by the availability of external haem . When there is enough haem, the HasS antisigma activity is turned off and HasI induces the transcription of hasS . This leads to the storage of inactive HasS molecules which become active when HasR is not occupied by holo-haemophore ligand molecules: as soon as there is a haem shortage transcription is turned off . Positive autoregulation of ECF sigma and antisigma genes is usually considered as a mechanism for amplifying a perceived signal . However, our findings suggest, on the contrary, that antisigma regulation allows fine-tuning to the external signal . The biological significance of ECF sigma and antisigma autoregulation may need to be reconsidered.

Ophthalmology, 2004 Aug, 111(8), 1495 - 503; discussion 1503
Bleb-associated endophthalmitis: clinical characteristics and visual outcomes; Busbee BG et al.; PURPOSE: To analyze the clinical characteristics and treatment outcomes of patients with bleb-associated endophthalmitis (BAE) . DESIGN: Retrospective, noncomparative, interventional case series . PARTICIPANTS: Consecutive patients treated at one institution for BAE . INTERVENTIONS: Prompt pars plana vitrectomy (PPV) with intravitreal injection of antibiotics, or prompt vitreous biopsy and intravitreal injection of antibiotics (tap and inject) . METHODS: Retrospective analysis of 68 consecutive cases of BAE between July 1, 1989 and June 30, 2001 . Clinical presentation, treatment modality, microbiologic data, and clinical course were analyzed . Visual outcomes were compared between vitrectomy and tap-and-inject groups, culture-positive and culture-negative groups, and early and late times . MAIN OUTCOME MEASURES: Snellen visual acuities (VAs) at 3 months and 12 months after treatment and at most recent follow-up . RESULTS: The incidence of no light perception (NLP) at 12 months after treatment for BAE was 35% . Vitreous isolates included streptococcal species (32% of positive cultures), Staphylococcus epidermidis (26%), Enterococcus, and Serratia (12% each) . Patients with a positive vitreous culture had significantly worse VA (median, hand movements {HM} at 3 and 12 months after treatment) and a higher rate of NLP vision . Patients treated with tap-and-inject had a significantly worse final VA (medians, HM at 3 months and LP at 12 months) and a significantly higher rate of NLP vision than patients treated with PPV . One third of patients who underwent PPV achieved a final VA of 20/100 or better 12 months after treatment (P = 0.09) . CONCLUSIONS: Bleb-associated endophthalmitis causes significant visual morbidity . Patients with culture-negative BAE and patients treated with prompt PPV may achieve better visual outcome.

Curr Eye Res, 2004 May, 28(5), 337 - 42
Quantitative comparison of fluoroquinolone therapies of experimental gram-negative bacterial keratitis; Thibodeaux BA et al.; PURPOSE: To determine the effectiveness of topically applied fluoroquinolones for experimental Pseudomonas or Serratia keratitis . METHODS: Bacteria were injected intrastromally (10(3) colony forming units {CFU}) . From 16 to 22 hours post-infection (PI), a single topical drop of moxifloxacin (Vigamox, 0.545%), levofloxacin (Quixin, 0.5%), ofloxacin (Ocuflox, 0.3%) or ciprofloxacin (Ciloxan, 0.3%) was applied every 30 minutes . At 23 hours PI, corneas were cultured quantitatively . RESULTS: For Pseudomonas keratitis, untreated eyes contained 7 log CFU/cornea and antibiotic-treated eyes demonstrated a > or = 5-log reduction in CFU/cornea (p < or = 0.0001) . Moxifloxacin, levofloxacin, or ciprofloxacin therapies were not significantly different from each other (p > or = 0.67) . For Serratia keratitis, untreated eyes contained 7 logCFU/cornea whereas treated eyes had a > or = 2-log reduction (p < or = 0.0001) . Moxifloxacin therapy proved most effective (p < or = 0.001) . CONCLUSIONS: Overall, moxifloxacin was the most effective of the four fluoroquinolones in reducing CFU/cornea in the rabbit model of gram-negative keratitis.

J Appl Microbiol, 2004, 97(3), 656 - 62
Mineral and carbon usage of two synthetic pyrethroid degrading bacterial isolates; Grant RJ et al.; AIMS: To investigate the biodegrading ability and cometabolism of synthetic pyrethroid (SP) utilizing bacteria in cultures with various minerals and carbon sources . METHODS AND RESULTS: Previously isolated SP-degrading Pseudomonas sp . and Serratia sp . were used in cultures containing either flumethrin SP or cypermethrin SP formulations . The culture media consisted of either (i) water only, (ii) water and sucrose, (iii) mineral broth or (iv) mineral broth and sucrose . The growth of both organisms was greatest in the mineral broth and sucrose medium, but the growth-limiting factor for Pseudomonas sp . strain Circle was the mineral content whereas for Serratia sp . strain White it was the carbon substrate . CONCLUSION: The greatest extent of degradation of both SP-based compounds occurred with Pseudomonas sp . strain Circle but was dependant on the medium . SIGNIFICANCE AND IMPACT OF THE STUDY: This investigation could lead to the development of a relatively inexpensive medium supplement to enhance the microbial biodegradation of undesirable compounds, either in situ or ex situ . In this particular case, for the biodegradation of SPs used in sheep dip .

Biotechnol Lett, 2004 May, 26(10), 799 - 802
Biosurfactant production by Serratia marcescens SS-1 and its isogenic strain SMdeltaR defective in SpnR, a quorum-sensing LuxR family protein; Wei YH et al.; Serratia marcescens SS-1 and its SpnR-defective isogenic mutant, SMdeltaR, produced an extracellular surfactant able to decrease surface tension of water from 72 to 37 dyne cm(-1) (SMdeltaR strain) and to 45 dyne cm(-1) (SS-1 strain) . The biosurfactant also emulsified kerosene and diesel with a maximum emulsion index of 77% (diesel and kerosene) for the SMdeltaR strain, and 72% (kerosene) and 40% (diesel) for the SS-1 strain . Deletion of spnR gene appeared to enhance biosurfactant production . Model simulations suggest that biosurfactant production by the two strains was growth-associated . The SMdeltaR strain had a yield coefficient of 22-32% g dry cell(-1), which is 32-50% higher than that of the SS-1 strain.

Indian J Exp Biol, 2003 Mar, 41(3), 248 - 54
Chitin degrading potential of bacteria from extreme and moderate environment; Nawani NN et al.; Five hundred chitin-degrading bacteria were isolated from 20 different locations . High percentage of potent chitin-degraders was obtained from polluted regions . Potent chitin-degrading bacteria were selected by primary and secondary screening . Among the selected isolates, 78% were represented by the genus Streptomyces . Majority of the isolates had good chitinolysis relative to the growth although isolates with better growth were also seen . Such isolates are important for the production of SCP from chitinous wastes . The potent isolates belonged to the genera Streptomyces, Kitasatosporia, Saccharopolyspora, Nocardioides, Nocardiopsis, Herbidospora, Micromonospora, Microbispora, Actinoplanes, Serratia, Bacillus and Pseudomonas . This study forms a comprehensive base for the study of diversity of chitinolytic systems of bacteria.

J Bacteriol, 2004 Aug, 186(15), 4986 - 93
The global regulator genes from biocontrol strain Serratia plymuthica IC1270: cloning, sequencing, and functional studies; Ovadis M et al.; The biocontrol activity of various fluorescent pseudomonads towards plant-pathogenic fungi is dependent upon the GacA/GacS-type two-component system of global regulators and the RpoS transcription sigma factor . In particular, these components are required for the production of antifungal antibiotics and exoenzymes . To investigate the effects of these global regulators on the expression of biocontrol factors by plant-associated bacteria other than Pseudomonas spp., gacA/gacS and rpoS homologues were cloned from biocontrol strain IC1270 of Serratia plymuthica, which produces a set of antifungal compounds, including chitinolytic enzymes and the antibiotic pyrrolnitrin . The nucleotide and deduced protein sequence alignments of the cloned gacA/gacS-like genes-tentatively designated grrA (global response regulation activator) and grrS (global response regulation sensor) and of the cloned rpoS gene revealed 64 to 93% identity with matching genes and proteins of the enteric bacteria Escherichia coli, Pectobacterium carotovora subsp . carotovora, and Serratia marcescens . grrA, grrS, and rpoS gene replacement mutants of strain IC1270 were deficient in the production of pyrrolnitrin, an exoprotease, and N-acylhomoserine lactone quorum-sensing signal molecules . However, neither mutant appeared to differ from the parental strain in the production of siderophores, and only grrA and grrS mutants were deficient in the production of a 58-kDa endochitinase, representing the involvement of other sigma factors in the regulation of strain IC1270's chitinolytic activity . Compared to the parental strain, the grrA, grrS, and rpoS mutants were markedly less capable of suppressing Rhizoctonia solani and Pythium aphanidermatum under greenhouse conditions, indicating the dependence of strain IC1270's biocontrol property on the GrrA/GrrS and RpoS global regulators.

J Invertebr Pathol, 2004 Jul, 86(3), 72 - 6
Quantification and kinetics of the decline in grass grub endopeptidase activity during initiation of amber disease; Jackson TA et al.; Amber disease in the grass grub (Costelytra zealandica White) (Coleoptera: Scarabaeidae), caused by strains of the bacteria Serratia entomophila or S . proteamaculans, is characterised by cessation of feeding and clearance of the midgut . Analysis of the midgut enzyme activity in diseased grass grub larvae showed that proteolytic activity was reduced to low levels . The endopeptidases, trypsin, elastase, and chymotrypsin, were all markedly reduced in activity whereas the exopeptidases (leucine-aminopeptidase and carboxypeptidase A and B) were much less affected . There was no effect on the non-proteolytic enzymes, esterase and alpha-amylase . Sequential analysis of enzyme levels in the gut during onset of disease showed that proteolytic activity dropped after cessation of feeding and preceded gut clearance . In starved, uninfected larvae enzyme activity levels remained high, indicating that decline in enzyme activity is not associated with absence of food and cessation of feeding, but with the onset of disease.

Folia Microbiol (Praha), 2004, 49(3), 321 - 6
Proteolytic activity in Serratia marcescens clinical isolates; Coria-Jimenez R et al.; Exoproteinase production was demonstrated in 64 clinical isolates of S . marcescens . A significant relationship was found between the site of origin (autopsy material, hemocultures, various other sources), proteinase activity, and LD50 of the analyzed isolates . The number of exoproteinases varied during a 14-h incubation in batch cultures; the most frequently found was a 57.5-kDa proteinase which was observed in all analyzed strains . The exoproteinase production was shown to be related to strain virulence.

Cell Tissue Bank, 2002, 3(1), 45 - 47
Devastating endophthalmitis caused by Serratia marcescens in two recipients after transplantation of corneal grafts from the same donor; Levartovsky S et al.; We report two cases of severe endophthalmitis, which were caused by Serratia marcescens, and developed in the immediate postoperative period in two recipients of corneal grafts from the same donor . The cause of the donor's death was massive CVA . He had been on mechanical ventilation for 12 days before he died, and had shown no sign of infectious disease while in the hospital . Vitrectomies were performed in the recipients' eyes on the third day after corneal transplantation . On the same day, and again 1day later, the transplanted eyes were injected intravitreally with vancomycin and ceftazidime . Two months after surgery, both eyes developed phthisis . These cases are similar to other rare reported cases describing the virulence of S . marcescens.

J Clin Microbiol, 2004 Jul, 42(7), 3374 - 6
Bacteriology of a bear bite wound to a human: case report; Kunimoto D et al.; Human contact with bears has become more frequent, as has the resultant bear maulings and bite injuries . We report the bacteriology of a patient bitten by a grizzly bear (Ursus arctos) from the Rocky Mountains foothills area east of Banff National Park, Alberta, Canada . The patient received field care, including metronidazole and cefazolin . Subsequent deep-wound cultures grew Serratia fonticola, Serratia marcescens, Aeromonas hydrophila, Bacillus cereus, and Enterococcus durans but no anaerobes.

J Nucl Med, 2004 Jul, 45(7), 1209 - 16
(123)I-Labeled chitinase as specific radioligand for in vivo detection of fungal infections in mice; Siaens R et al.; Given the scarcity of diagnostic tools for invasive fungal infections, the aim of this project was to develop new, specific radiopharmaceuticals for diagnosis of fungal infections . Chitin, which is expressed in the fungal cell wall but is absent in mammalian and bacterial cells, represents a potentially selective target for development of tracers for fungal infections . ChiB_E144Q (ChiB = chitinase B) from Serratia marcescens was labeled with (123)I, and in vitro and in vivo studies were assessed . METHODS: (123)I labeling of ChiB_E144Q from S . marcescens by direct iodination was characterized by high-pressure liquid chromatography (HPLC), and stability was evaluated . The in vitro binding properties of the compound to living bacteria, Candida albicans, and Aspergillus fumigatus were examined . Scintigraphy was performed and in vivo characteristics were studied in mice with infected thigh muscles . RESULTS: An average radiochemical yield of 35% was obtained . Radiochemical purity was >97% with a stability of >24 h as determined by HPLC and instant thin-layer chromatography . The average specific activity of the noncarrier-free (123)I-chitinase was 9.25 MBq/ micro g of enzyme . Binding assays showed virtually no binding to Eschericha coli and Staphylococcus aureus, and 2.4 x 10(3) Bq per 1 x 10(7) cells for A . fumigatus and 3.0 x 10(3) Bq per 1 x 10(7) cells for C . albicans (P < 0.05) . Binding of the tracer dropped to almost zero for organisms previously incubated with a 50-fold excess of unlabeled enzyme . At 24 h after injection, target-to-nontarget (T/NT) ratios in mice were 20.6 +/- 3.6 for C . albicans and 15.2 +/- 3.7 for A . fumigatus infections, respectively, whereas T/NT ratios for S . aureus -and E . coli-infected thigh muscles or thigh muscles with a sterile inflammation did not exceed 4.9 +/- 2.6, 3.0 +/- 2.3, and 5.3 +/- 2.8, respectively (P < 0.05) . Target-to-blood ratios for fungus-infected thighs were always >1 . CONCLUSION: Our results show that (123)I-ChiB_E144Q has affinity in vitro for fungi . In vivo, the tracer accumulates in tissue infected with C . albicans and A . fumigatus but not in tissue infected with gram-positive or gram-negative bacteria, or in sterile inflammations, proving it to be a valuable SPECT diagnostic.

J Antimicrob Chemother, 2004 Aug, 54(2), 370 - 5 Epub 2004 Jul 01.
Identification of genes involved in the susceptibility of Serratia marcescens to polyquaternium-1; Codling CE et al.; OBJECTIVES: Polyquaternium-1 (PQ-1) is a biocide used commercially in a contact lens disinfecting solution, 'Opti-Free Express (Alcon) Multi-Purpose Disinfecting Solution' . The genetic basis for resistance of Serratia marcescens to PQ-1 was investigated using a random transposon-based mutagenesis approach . METHODS: S . marcescens was subjected to random transposon mutagenesis using a mini-Tn5 Km2 transposon . Mutants with increased susceptibility to PQ-1 were selected and the disrupted genes were identified . Antibiotic susceptibility profiles were also determined for all of the mutants . RESULTS: A wide range of genes were found to be disrupted in the mutants . The most common were genes associated with the cell membranes, or involved in biosynthesis and metabolism . CONCLUSIONS: This study shows that random transposon mutagenesis is an effective tool for the elucidation of mechanisms of action and resistance to biocides . The results support our previous findings that PQ-1 is active against the cytoplasmic membrane of S . marcescens.

Exp Parasitol, 2004 May-Jun, 107(1-2), 89 - 96
Isolation of Serratia marcescens in the midgut of Rhodnius prolixus: impact on the establishment of the parasite Trypanosoma cruzi in the vector; Azambuja P et al.; The effects of resident bacteria in the stomach of 5th-instar larvae of Rhodnius prolixus on the erythrocyte lysis and Trypanosoma cruzi infection were studied . The bacteria population increased approximately 10,000-fold after feeding . Hemolysis rose to approximately 28% within 24h postfeeding and then linearly grew until day 4 attaining almost 100% . The number of surviving Y strain of T . cruzi in the stomach declined drastically, while the infection with Dm28c clone was maintained stable . Five days after feeding, few different types of bacterial colonies were obtained when stomach content suspensions were spread onto BHI agar plates . The hemolytic bacteria were isolated and identified as Serratia marcescens biotype A1a (referenced as RPH), which produces the pigment prodigiosin . In vitro experiments, comparing incubations of RPH with S . marcescens SM365, a prodigiosin pigment producer, and S . marcescens DB11, a nonpigment variant, as a control, with erythrocytes and T . cruzi demonstrated that: (i) at 30 degrees C, SM365 and RPH diminished the populations of Y strain, but not DM28c clone, and DB11 was unable to lyse both T . cruzi strains; (ii) at 0 degrees C, SM263 and RPH killed the flagellates, but DB11 did not; and (iii) all three strains of S . marcescens were able to lyse erythrocytes . These results suggest that S . marcescens trypanolytic activity from the SM365 and RPH strains is distinct from the hemolytic activity and that prodigiosin is an important factor for the trypanolytic action of the bacteria.

J Bacteriol, 2004 Jul, 186(13), 4067 - 74
Free and hemophore-bound heme acquisitions through the outer membrane receptor HasR have different requirements for the TonB-ExbB-ExbD complex; Letoffe S et al.; Many gram-negative bacteria have specific outer membrane receptors for free heme, hemoproteins, and hemophores . Heme is a major iron source and is taken up intact, whereas hemoproteins and hemophores are not transported: the iron-containing molecule has to be stripped off at the cell surface, with only the heme moiety being taken up . The Serratia marcescens hemophore-specific outer membrane receptor HasR can transport either heme itself or heme bound to the hemophore HasA . This second mechanism is much more efficient and requires a higher TonB-ExbB-ExbD (TonB complex) concentration than does free or hemoglobin-bound heme uptake . This requirement for more of the TonB complex is associated with a higher energy requirement . Indeed, the sensitivity of heme-hemophore uptake to the protonophore carbonyl cyanide m-chlorophenyl hydrazone is higher than that of heme uptake from hemoglobin . We show that a higher TonB complex concentration is required for hemophore dissociation from the receptor . This dissociation is concomitant with heme uptake . We propose that increasing the TonB complex concentration drives more energy to the outer membrane receptor and speeds up the release of empty hemophores, which, if they remained on receptors, would inhibit heme transport.

Biotechnol Lett, 2004 Apr, 26(8), 681 - 6
Tributyl phosphate degradation by Serratia odorifera; Berne C et al.; Several strains from tributyl phosphate (TBP)-polluted soils were isolated and screened for their ability to degraded this widely used organophosphorus compound . The most active strain, identified as Serratia odorifera, degrades up to 600 microM TBP (initially present in the medium at 2 mM) during its growth phase, within 8 h from inoculation . However, this bacterium could not utilize TBP as the sole carbon and/or phosphorus source but nevertheless is a good candidate for bioremediation of TBP-polluted industrial sites.

Int J Antimicrob Agents, 2004 Jun, 23(6), 627 - 30
Influence of the cell wall on ciprofloxacin susceptibility in selected wild-type Gram-negative and Gram-positive bacteria; Berlanga M et al.; The susceptibility of several wild-type bacteria to ciprofloxacin and accumulation of the drug in these bacteria were evaluated . Species studied included Escherichia coli, Serratia marcescens, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis and Bacillus cereus . Ciprofloxacin susceptibility was measured for each strain using two different methods: the minimal inhibitory concentration and the bactericidal index . Significant differences were observed between the results derived from these two methods . Whereas the minimal inhibitory concentration was low in all strains tested, ciprofloxacin's bactericidal activity, as indicated by the bactericidal index, varied with the species studied . To determine whether this finding was due to variations in cell envelope permeability to ciprofloxacin (i.e . to combined cell uptake and efflux), we studied ciprofloxacin accumulation using spectrofluorometry . In Gram-negative bacteria, differences in permeability can lead to altered susceptibility to antibiotics . In fact, the combination of slow uptake and efficient efflux seems to be crucial to the characteristic poor susceptibility of P . aeruginosa to ciprofloxacin . However, the low level of activity of ciprofloxacin against S . aureus and two Bacillus species may have resulted from the drug's interaction with its target enzymes (i.e . topoisomerase IV in S . aureus and DNA gyrase in Bacillus spp.) rather than diminished permeability .

BMC Infect Dis . 2004 Jun 09;4(1):16.
Serratia marcescens internalization and replication in human bladder epithelial cells; Hertle R et al.; BACKGROUND: Serratia marcescens, a frequent agent of catheterization-associated bacteriuria, strongly adheres to human bladder epithelial cells in culture . The epithelium normally provides a barrier between lumal organisms and the interstitium; the tight adhesion of bacteria to the epithelial cells can lead to internalization and subsequent lysis . However, internalisation was not shown yet for S . marcescens strains . METHODS: Elektronmicroscopy and the common gentamycin protection assay was used to assess intracellular bacteria . Via site directed mutagenesis, an hemolytic negative isogenic Serratia strain was generated to point out the importance of hemolysin production . RESULTS: We identified an important bacterial factor mediating the internalization of S . marcescens, and lysis of epithelial cells, as the secreted cytolysin ShlA . Microtubule filaments and actin filaments were shown to be involved in internalization . However, cytolysis of eukaryotic cells by ShlA was an interfering factor, and therefore hemolytic-negative mutants were used in subsequent experiments . Isogenic hemolysin-negative mutant strains were still adhesive, but were no longer cytotoxic, did not disrupt the cell culture monolayer, and were no longer internalized by HEp-2 and RT112 bladder epithelial cells under the conditions used for the wild-type strain . After wild-type S . marcescens became intracellular, the infected epithelial cells were lysed by extended vacuolation induced by ShlA . In late stages of vacuolation, highly motile S . marcescens cells were observed in the vacuoles . S . marcescens was also able to replicate in cultured HEp-2 cells, and replication was not dependent on hemolysin production . CONCLUSION: The results reported here showed that the pore-forming toxin ShlA triggers microtubule-dependent invasion and is the main factor inducing lysis of the epithelial cells to release the bacteria, and therefore plays a major role in the development of S . marcescens infections.

Microbiology, 2004 Jun, 150(Pt 6), 1901 - 10
luxS mutants of Serratia defective in autoinducer-2-dependent 'quorum sensing' show strain-dependent impacts on virulence and production of carbapenem and prodigiosin; Coulthurst SJ et al.; The enzyme LuxS is responsible for the production of autoinducer-2 (AI-2), a molecule that has been implicated in quorum sensing in many bacterial species . This study investigated whether there is a luxS-dependent signalling system in the Gram-negative bacteria Serratia spp . Serratia marcescens is a broad-host-range pathogen and an important cause of nosocomial infections . Production of AI-2 activity was detected in S . marcescens ATCC 274 and Serratia ATCC 39006 and their luxS genes were sequenced . luxS mutants were constructed in these strains and were analysed to determine which phenotypes are regulated by luxS and therefore, potentially, by AI-2 . The phenotypes of the luxS mutants included decreased carbapenem antibiotic production in Serratia ATCC 39006 and decreased prodigiosin and secreted haemolysin production in S . marcescens ATCC 274 . The luxS mutant of S . marcescens ATCC 274 was also found to exhibit modestly reduced virulence in a Caenorhabditis elegans model . Finally, it was shown that the culture supernatant of a wild-type strain contains a signal, presumably AI-2, capable of complementing the prodigiosin defect of the luxS mutant of another strain, even when substantially diluted . It is concluded that luxS modulates virulence and antibiotic production in Serratia, in a strain-dependent manner, and that, for at least one phenotype, this regulation is via extracellular signalling.

Appl Environ Microbiol, 2004 Jun, 70(6), 3781 - 4
Short-duration low-direct-current electrical field treatment is a practical tool for considerably reducing counts of gram-negative bacteria entrapped in gel beads; Zvitov R et al.; Application of a direct-current electrical field for very short times can serve as a practical nonthermal procedure to reduce or modify the microbial distribution in gel beads . The viability of Escherichia coli and Serratia marcescens entrapped in alginate and agarose beads decreases as the field intensity and duration of electrical field increase.

Diagn Microbiol Infect Dis, 2004 Jun, 49(2), 125 - 9
Survey of CTX-M-3 extended-spectrum beta-lactamase (ESBL) among cefotaxime-resistant Serratia marcescens at a medical center in middle Taiwan; Wu LT et al.; Thirty-four clinical isolates of Serratia marcescens nonsusceptible to cefotaxime were collected from a medical center in middle Taiwan . Confirmatory tests for extended-spectrum beta-lactamases (ESBLs) by cefotaxime and ceftazidime +/- clavulanic acid using Etest ESBL Screen identified only one ESBL producer; the remaining 33 isolates revealed nondeterminable results, because of off-scale minimum inhibitory concentration (MIC) levels for cefotaxime +/- clavulanic acid . Agar microdilution method using broader MIC ranges confirmed 21 ESBL-producers and one non-determinable result, achieving a highly predicting value compared to golden standard by PCR and DNA sequencing analysis, which identified 22 (65%) isolates containing blaCTX-M-3 genes . Only one strain carried concurrent CTX-M-3 and SHV-5 conferring high-level MICs to both cefotaxime (128 microg/mL) and ceftazidime (64 microg/mL) . Other enzymatic mechanisms, such as chromosome-encoded AmpC including a novel SRT-2 enzyme, may confer resistance to cefotaxime on the remaining 12 isolates without ESBL bla genes . Thus, it is unreliable to predict the resistance mechanism by antibiogram, and current Etest ESBL Screen tests . Our study highlights expanding efforts to detect ESBLs in S . marcescens are urgently needed in Taiwan .

FEBS Lett, 2004 Jun 4, 567(2-3), 307 - 10
Kinetic evidence related to substrate-assisted catalysis of family 18 chitinases; Honda Y et al.; The hydrolytic reaction of family 18 chitinase has been considered to occur via substrate assisted catalysis . To kinetically investigate the enzyme reaction mechanism, we synthesized compounds designed to reduce the polarization of the carbonyl in N-acetyl group, GlcNAc-GlcN(TFA)-UMB (2) and GlcNAc-GlcN(TAc)-UMB (3) . Kinetic parameters in the hydrolysis of these compounds by chitinase A from Serratia marcescens (ChiA) were compared with those from the hydrolysis of (GlcNAc)2-UMB (1) . The kcat of 2 was 3.4% of 1, but the Km of 2 was 10-fold that of 1 . In contrast, the kcat of 3 was only 0.3% of that of 1, and the two reactions had an identical Km . The drastic decreases in kcat were probably due to the weak nucleophilic activity of the C2-N-trifluoroacetamide and N-thioacetamide groups at reducing ends of compounds 2 and 3, respectively . These results indicate that the anchimeric assistance of the C2 N-acetamide group at GlcNAc plays a key role in the hydrolytic reactions catalyzed by family 18 chitinases.

Antimicrob Agents Chemother, 2004 Jun, 48(6), 2321 - 4
Molecular characterization of a carbapenem-hydrolyzing class A beta-lactamase, SFC-1, from Serratia fonticola UTAD54; Henriques I et al.; An environmental isolate of Serratia fonticola resistant to carbapenems contains a gene encoding a class A beta-lactamase with carbapenemase activity . The enzyme was designated SFC-1 . The bla(SFC-I) gene is contained in the chromosome of S . fonticola UTAD54 and is absent from other S . fonticola strains.

Singapore Med J, 2004 May, 45(5), 214 - 8
Using pulsed-field gel electrophoresis in the molecular investigation of an outbreak of Serratia marcescens infection in an intensive care unit; Alfizah H et al.; INTRODUCTION: Serratia marcescens is a well-known cause of nosocomial infections and outbreaks, particularly in immunocompromised patients with severe underlying disease . An outbreak due to S . marcescens infection was detected from 13 to 22 February 2001 at the intensive care unit (ICU) of our institution . We used pulsed-field gel electrophoresis (PFGE) typing to analyse the outbreak strains involved . METHODS: A total of 25 isolates were included in this study: 12 isolates from infected patients, nine isolates from insulin solution, one isolate from sedative solution (midazolam and morphine infusion) and one isolate from frusemide solution . Two isolates from other wards which were epidemiologically-unrelated were also included . RESULTS: The S . marcescens from patients, insulin solution and sedative solution showed an identical PFGE fingerprint pattern . The isolate from the frusemide solution had a closely-related PFGE pattern to the outbreak strain with one band difference . Attempts were made in the present study to identify the environmental reservoir of S . marcescens during the outbreak . We found that the insulin and sedative solutions used by the patients were contaminated with S . marcescens which was proven to be the source of the outbreak . CONCLUSION: Using PFGE, we showed that the outbreak in the ICU of our hospital was due to the clonal spread of a single strain of S . marcescens.

Protein Expr Purif, 2004 Jun, 35(2), 264 - 71
Isolation, cloning, and overexpression of a chitinase gene fragment from the hyperthermophilic archaeon Thermococcus chitonophagus: semi-denaturing purification of the recombinant peptide and investigation of its relation with other chitinases; Andronopoulou E et al.; A 189-bp sequence was isolated from the hyperthermophilic archaeon Thermococcus chitonophagus and was found to present strong homology with a large number of chitinase genes from a variety of organisms and particularly with the chitinaseA gene from Pyrococcus kodakaraensis (Pk-chiA) . This fragment was subcloned to an expression vector and overexpressed in Escherichia coli . The E . coli BLR21(DE3)pLysS transformant, harbouring the gene on the pET-31b plasmid vector, was found to overproduce the target protein at high levels . The 63 aminoacid-long peptide was efficiently purified to homogeneity, with a one-step, semi-denaturing affinity chromatography, on a metal chelation resin and was used for the production of a specific, polyclonal antibody from rabbits . The produced antibody was demonstrated to display strong and specific affinity for the chitinase A from Serratia marcescens (Sm-chiA), as well as the membrane-bound chitinase70 from Thermococcus chitonophagus (Tc-Chi70) . The strong sequence homology, in combination with the demonstrated specific immunochemical affinity, indicates that the isolated peptide is part of a chitinolytic enzyme of T . chitonophagus . In particular, it could belong to the membrane-bound chi70, or to a distinct chitinase, coded by a different gene, or even by the same gene, following post-transcriptional or post-translational modifications.

BMC Microbiol . 2004 Mar 18;4(1):11.
A novel medium for the enhanced cell growth and production of prodigiosin from Serratia marcescens isolated from soil; Giri AV et al.; BACKGROUND: Prodigiosin produced by Serratia marcescens is a promising drug owing to its reported characteristics of having antifungal, immunosuppressive and antiproliferative activity . From an industrial point of view the necessity to obtain a suitable medium to simultaneously enhance the growth of Serratia marcescens and the pigment production was the aim of this work . The usage of individual fatty acid as substrate in industries would be cost-effective in the long run and this paved the way for us to try the effect of different fatty acid-containing seeds and oils of peanut, sesame and coconut as source of substrate . RESULTS: The addition of sugars only showed slight enhancement of prodigiosin production in nutrient broth but not in fatty acid containing seed medium . The powdered peanut broth had supported better growth of Serratia marcescens and higher yield of prodigiosin when compared with the existing nutrient broth and peptone glycerol broth . A block in prodigiosin production was seen above 30 degrees C in nutrient broth, but the fatty acid seed medium used by us supported prodigiosin production upto 42 degrees C though the yields were lower than what was obtained at 28 degrees C . From the results, the fatty acid form of carbon source has a role to play in enhanced cell growth and prodigiosin production . CONCLUSION: We conclude by reporting that the powdered and sieved peanut seed of different quality grades were consistent in yielding a fourty fold increase in prodigiosin production over the existing media . A literature survey on the composition of the different media components in nutrient broth, peptone glycerol broth and the fatty acid containing seeds and oils enabled us to propose that the saturated form of fatty acid has a role to play in enhanced cell growth and prodigiosin production . This work has also enabled us to report that the temperature related block of prodigiosin biosynthesis varies with different media and the powdered peanut broth supports prodigiosin production at higher temperatures . The medium suggested in this work is best suitable from an industrial point of view in being economically feasible, in terms of the higher prodigiosin yield and the extraction of prodigiosin described in this paper is simple with minimal wastage.

Biophys Chem, 2004 May 1, 109(2), 215 - 27
Molecular and functional characterisation of the Serratia marcescens outer membrane protein Omp1; Ruiz N et al.; Serratia marcescens outer membrane contains three different general diffusion porins: Omp1, Omp2 and Omp3 . Omp1 was cloned and sequenced and it shows a great homology to the family of outer membrane porins that comprises the general porins of enteric bacteria . The gene for Omp1 was transferred into an expression plasmid and was expressed in Escherichia coli UH302 (E . coli UH302 pOM100), a porin deficient strain . Its expression confers a higher susceptibility towards different antibiotics to this strain . Omp1 was purified to homogeneity from outer membrane of E . coli UH302 pOM100 . Reconstitution of the purified protein into black lipid bilayers demonstrated that it is a channel-forming component with a single-channel conductance of approximately 2 nS in 1 M KCl similar to that of other porins from enteric bacteria . Omp1 is slightly cation-selective . Its homology to already crystallised members of the family of enteric porins whose three-dimensional-structures are known and allowed the design of a topology model for Omp1 . The charge distribution within a porin monomer is similar as in other general diffusion pores . The positively charged amino acids localised at the beta-strands opposite the external loop L3, which restrict the pore diameter in the porin monomer .

Cornea, 2004 May, 23(4), 360 - 4
Trends in the etiology of infectious corneal ulcers at the F . I . Proctor Foundation; Varaprasathan G et al.; OBJECTIVE: We analyzed laboratory results from corneal ulcers seen from 1976 to 1999 at the Francis I . Proctor Foundation, a referral center in San Francisco, to determine the relative frequencies of pathogens and to analyze for trends in frequencies of the most common pathogens . The results were compared with a previous study of corneal ulcers seen from 1948 to 1976 at the same institution . METHODS: Ulcers presenting to the Proctor Foundation were Gram stained and cultured using standard techniques . Herpetic corneal ulcers were excluded from the study . RESULTS: Organisms were isolated from 427 ulcers, 38% of all cases . Two hundred seventy-eight (59%) isolates were gram-positive bacteria, 145 (31%) gram-negative bacteria, 16 (3%) Acanthamoeba spp., and 36 (8%) fungi . Staphylococcus aureus was the most common organism, composing 20% of all isolates, followed by viridans group streptococci (12%), Streptococcus pneumoniae (11%), Pseudomonas aeruginosa (6%), Moraxella spp . (5%), and Serratia marcescens (4%) . Over the 24-year study period the proportion of positive cultures decreased and the incidence of S . marcescens increased significantly . Comparing the period of 1948-1976 to 1976-1999, the frequency of S . pneumoniae and P . aeruginosa decreased, and that of S . marcescens increased significantly . CONCLUSION: The common pathogens associated with corneal ulcers have changed over the past 50 years in Northern California, with S . pneumoniae and P . aeruginosa being isolated relatively less often and S . marcescens being isolated with increasing frequency . The decrease in isolation of organisms over the 1976-1999 period may have resulted from increasing empiric antibiotic treatment by referring ophthalmologists.

Appl Environ Microbiol, 2004 Apr, 70(4), 2021 - 7
Size and UV germicidal irradiation susceptibility of Serratia marcescens when aerosolized from different suspending media; Lai KM et al.; Experimental systems have been built in laboratories worldwide to investigate the influence of various environmental parameters on the efficacy of UV germicidal irradiation (UVGI) for deactivating airborne microorganisms . It is generally recognized that data from different laboratories might vary significantly due to differences in systems and experimental conditions . In this study we looked at the effect of the composition of the suspending medium on the size and UVGI susceptibility of Serratia marcescens in an experimental system built in our laboratory . S . marcescens was suspended in (i) distilled water, (ii) phosphate buffer, (iii) 10% fetal calf serum, (iv) phosphate-buffered saline (saline, 0.8% sodium chloride), and (v) synthetic saliva (phosphate-buffered saline with 10% fetal calf serum) . At low humidity (36%), S . marcescens suspended in water-only medium was the most susceptible to UVGI, followed by those in serum-only medium . The count median diameters (CMDs) for culturable particles from water-only and serum-only media were 0.88 and 0.95 micro m, respectively, with the measurements based on their aerodynamic behavior . The bacteria suspended in phosphate buffer, synthetic saliva, and phosphate-buffered saline had similar UVGI susceptibility and CMD at 1.0, 1.4, and 1.5 micro m, respectively . At high humidity (68%) the CMD of the particles increased by 6 to 16%, and at the same time UVGI susceptibility decreased, with the magnitude of decrease related to the type of suspending medium . In conclusion, the choice of suspending medium influenced both size and UVGI susceptibility of S . marcescens . These data are valuable for making comparisons and deciding on the use of an appropriate medium for various applications.

J Mol Biol, 2004 Apr 23, 338(2), 217 - 28
Structural and functional characterization of mitochondrial EndoG, a sugar non-specific nuclease which plays an important role during apoptosis; Schafer P et al.; Combining sequence analysis, structure prediction, and site-directed mutagenesis, we have investigated the mechanism of catalysis and substrate binding by the apoptotic mitochondrial nuclease EndoG, which belongs to the large family of DNA/RNA non-specific betabetaalpha-Me-finger nucleases . Catalysis of phosphodiester bond cleavage involves several highly conserved amino acid residues, namely His143, Asn174, and Glu182 required for water activation and metal ion binding, as well as Arg141 required for proper substrate binding and positioning, respectively . These results indicate that EndoG basically follows a similar mechanism as the Serratia nuclease, the best studied representative of the family of DNA/RNA non-specific nucleases, but that differences are observed for transition state stabilisation . In addition, we have identified two putative DNA/RNA binding residues of bovine EndoG, Arg135 and Arg186, strictly conserved only among mammalian members of the nuclease family, suggesting a similar mode of binding to single and double-stranded nucleic acid substrates by these enzymes . Finally, we demonstrate by ectopic expression of active and inactive variants of bovine EndoG in HeLa and CV1-cells that extramitochondrial active EndoG by itself induces cell death, whereas expression of an enzymatically inactive variant does not.

Infect Control Hosp Epidemiol, 2004 Mar, 25(3), 216 - 20
Conjunctival colonization of infants hospitalized in a neonatal intensive care unit: a longitudinal analysis; Raskind CH et al.; OBJECTIVES: To determine the frequency of conjunctival colonization, identify the colonizing flora, and correlate culture results with physical findings in infants in a NICU . DESIGN: Surveillance study . SETTING: Level III NICU of a large university teaching hospital . PATIENTS: All infants admitted for longer than 24 hours during a 26-week period . METHODS: Weekly bacterial conjunctival cultures were performed for all infants . The conjunctival appearance at the time of culture was recorded . The frequency, identity, and correlation of culture results with physical findings were determined . RESULTS: One thousand ninety-one cultures were performed for 319 infants: 133 (42%) had no positive cultures and 186 (58%) had at least one positive culture . Culture analysis revealed that 411 (38%) were positive and yielded 494 isolates comprising more than 18 bacterial species . Bacteria most commonly isolated included coagulase-negative Staphylococcus (CoNS) (75%), viridans group streptococci (8.7%), Staphylococcus aureus (3.8%), Enterococcus species (2.6%), and Serratia marcescens (2.4%) . The frequency of non-CoNS isolates increased significantly during the first 6 weeks of patient hospital stay (6% {1 to 3 weeks} to 12% {4 to 6 weeks}; P = .01), with an increasing trend to 15 weeks (18%) . Correlation of bacteriologic results with physical findings demonstrated that infants with non-CoNS isolates exhibited conjunctival edema, erythema, or exudates more frequently than did infants with CoNS alone (30% vs 13%; P = .0001) . CONCLUSIONS: Conjunctival colonization was common among infants in a NICU . Prolonged hospitalization predisposes to colonization with potentially pathogenic organisms . Physical findings were more likely in patients with non-CoNS conjunctival isolates.

Arch Biochem Biophys, 2004 Apr 15, 424(2), 171 - 80
An endochitinase A from Vibrio carchariae: cloning, expression, mass and sequence analyses, and chitin hydrolysis; Suginta W et al.; We provide evidence that chitinase A from Vibrio carchariae acts as an endochitinase . The chitinase A gene isolated from V . carchariae genome encodes 850 amino acids expressing a 95-kDa precursor . Peptide masses of the native enzyme identified from MALDI-TOF or nanoESIMS were identical with the putative amino acid sequence translated from the corresponding nucleotide sequence . The enzyme has a highly conserved catalytic TIM-barrel region as previously described for Serratia marcescens ChiA . The Mr of the native chitinase A was determined to be 62,698, suggesting that the C-terminal proteolytic cleavage site was located between R597 and K598 . The DNA fragment that encodes the processed enzyme was subsequently cloned and expressed in Escherichia coli . The expressed protein exhibited chitinase activity on gel activity assay . Analysis of chitin hydrolysis using HPLC/ESI-MS confirmed the endo characteristics of the enzyme.

Arch Med Res, 2004 Jan-Feb, 35(1), 12 - 7
Identification of Serratia marcescens populations of nosocomial origin by RAPD-PCR; Enciso-Moreno JA et al.; BACKGROUND: Serratia marcescens has been increasingly identified as a cause of infection in the immunocompromised host and in high-mortality-rate nosocomial outbreaks . It is thus important to use identification methods that allow study of the dynamics and evolution of nosocomial S . marcescens strains . The aim of this study was to identify S . marcescens strains isolated from nosocomial outbreaks in two pediatric hospitals by random amplification polymorphic DNA polymerase chain reaction (RAPD-PCR) . METHODS: RAPD-PCR was used to study five S . marcescens populations isolated from four different nosocomial outbreaks that occurred in two pediatric hospitals . This method was compared with the widely used biotyping system described by Grimont and Grimont . RESULTS: The combination of biotypification and RAPD-PCR allowed accurate identification of S . marcescens strains isolated in nosocomial outbreaks at pediatric hospitals; by RAPD-PCR, we were able to analyze clonal variations in S . marcescens populations . We established bacterial dissemination patterns in hospital environments according to hospital administration of medical services and compared changes in bacterial DNA amplification patterns in each hospital related with clonal variations by selective pressures . CONCLUSIONS: RAPD-PCR is a useful method to identify S . marcescens strains associated with nosocomial outbreaks.

J Intensive Care Med, 2004 Jan-Feb, 19(1), 51 - 5
Drotrecogin alfa (activated) in an infant with gram-negative septic shock; Sajan I et al.; The authors observed the effect of drotrecogin alfa (activated) in a case of pediatric severe sepsis . A 4-month-old male infant with Serratia marcescens septic shock, multiple organ dysfunction syndrome (MODS), and consumptive coagulopathy was admitted . The safety and efficacy of drotrecogin alfa (activated) has not yet been established for patients younger than 18 years of age . This is the first published report of the use of drotrecogin alfa (activated) in an infant with severe sepsis . Within 6 hours of starting therapy, there was a significant improvement in hemodynamics, which was not maintained after the drotrecogin alfa (activated) infusion was temporarily discontinued . No significant bleeding complications occurred during the infusion . A brain MRI on day 22 after drotrecogin alfa (activated) infusion showed bilateral small occipital hemorrhages . Drotrecogin alfa (activated) in this infant was temporally related to significant improvement . It is unknown whether the MRI brain lesions are related to severe sepsis with disseminated intravascular coagulation or drotrecogin alfa (activated) infusion . The authors believe that drotrecogin alfa (activated) should be considered in select children with life-threatening severe sepsis.

Ann N Y Acad Sci, 2003 Dec, 1010, 178 - 81
Prodigiosin induces apoptosis by acting on mitochondria in human lung cancer cells; Llagostera E et al.; Prodigiosin (PG) is a secondary metabolite, isolated from a culture of Serratia marcescens, which has shown potent cytotoxicity against various human cancer cell lines as well as immunosuppressive activity . The purpose of this study was to evaluate the role of mitochondria in PG-induced apoptosis . Therefore, we evaluated the apoptotic action of PG in GLC4 small cell lung cancer cell line by Hoechst 33342 staining . In these cells, we examined mitochondrial apoptosis-inducing factor (AIF) and cytochrome c (cyt c) release to the cytosol in PG time-response studies . These findings suggest that PG induces apoptosis in both caspase-dependent and caspase-independent pathways.

Science, 2004 Mar 19, 303(5665), 1873 - 6
Genetic basis of natural variation in D . melanogaster antibacterial immunity; Lazzaro BP et al.; Many genes involved in Drosophila melanogaster innate immune processes have been identified, but whether naturally occurring polymorphism in these genes leads to variation in immune competence among wild flies has not been tested . We report here substantial variability among wild-derived D . melanogaster in the ability to suppress infection by a Gram-negative entomopathogen, Serratia marcescens . Variability in immune competence was significantly associated with nucleotide polymorphism in 16 innate immunity genes, corresponding primarily to pathogen recognition and intracellular signaling loci, and substantial epistasis was detected between intracellular signaling and antimicrobial peptide genes . Variation in these genes, therefore, seems to drive variability in immunocompetence among wild Drosophila.

J Cataract Refract Surg, 2004 Feb, 30(2), 507 - 12
Ulcerative keratitis caused by Serratia marcescens after laser in situ keratomileusis; Munoz G et al.; We report 2 cases of severe corneal infections caused by Serratia marcescens after laser in situ keratomileusis (LASIK) . Twenty-four hours after LASIK, 2 patients developed infectious keratitis, 1 bilaterally . In each eye, the corneal flap was edematous, ulcerated, and detached from the stromal bed . Treatment included removal of the necrotic flap and aggressive antibiotic therapy . Cultures from corneal exudates were positive for S marcescens . After 1 year, both patients had a loss of best corrected visual acuity (BCVA) ranging from 20/40 to 20/22 because of irregular astigmatism . Overrefraction with a hard contact lens resulted in a BCVA of 20/20 in the 3 affected eyes . Slitlamp examination showed trace subepithelial haze without severe corneal scarring . Videokeratography disclosed areas of paracentral inferior steepening resembling keratoconus . Refraction and videokeratography remained stable after 6 months of follow-up . Ulcerative keratitis caused by S marcescens is a potential complication of LASIK . Bilateral involvement may occur if bilateral simultaneous surgery is performed.

J Insect Physiol, 2004 Feb-Mar, 50(2-3), 209 - 16
Estimating disease resistance in insects: phenoloxidase and lysozyme-like activity and disease resistance in the cricket Gryllus texensis; Adamo SA; An animal's ability to resist disease is usually estimated by measuring one or more components of the immune system . There is an assumption that these assays of immunity measure an animal's ability to mount an effective immune response . This paper tests this assumption by examining the relationship between two common estimates of insect immunocompetence, phenoloxidase and lysozyme-like enzyme activity, and resistance to three common insect bacterial pathogens: Serratia marcescens, Serratia liquefaciens, and Bacillus cereus . There was a correlation (Spearman's rs=0.33, p<0.001, n=190 pairs) between total phenoloxidase and baseline lysozyme-like activity within individuals . However, total phenoloxidase and baseline lysozyme-like activity levels did not predict which male crickets would survive any of the three bacterial challenges . Lysozyme-like activity increased after an immune challenge (Friedman, 33.72, p<0.001), and the greater the increase, the greater the chance that the cricket would survive S . marcescens (slope=0.15, chi 2=8.2, p=0.005) or B . cereus (slope=0.8, chi 2=6.4, p=0.01) . The crickets with a greater total hemolymph protein concentration were also more likely to survive a challenge with any of the three bacterial pathogens than the crickets with lower total hemolymph protein concentrations (S . liquefaciens: slope=0.02, chi 2=9.2, p=0.002; B . cereus: slope=0.02, chi 2=6.5, p=0.01; S . marcescens: slope=0.03, chi 2=7.8, p=0.005) . Because of the complexity of the immune system, empirical tests of the relationship between assays of immunity and resistance to a range of actual pathogens are important for correctly interpreting these measures.

Nephrology (Carlton), 2003 Feb, 8(1), 16 - 20
Acute vascular access catheters for haemodialysis: complications limiting technique survival; Jefferys A et al.; The use of acute vascular access catheters (AVACs) has facilitated the delivery of haemodialysis to patients lacking functioning access . A review of the experience of a tertiary Australian renal treatment centre, consisting of 205 sequential AVACs in 93 patients, was undertaken over 1 year, to identify issues limiting technique survival . Acute vascular access catheters were inserted as acute dialysis access for patients with chronic renal failure (CRF; 21%), failed grafts or fistulae (18%), acute renal failure (12%), failed chronic ambulatory peritoneal dialysis (CAPD; 8%) or failed prior AVACs (37%) . The majority of AVACs were on the right (74%), and the placement site was simple jugular (69%), tunnelled jugular (15%), femoral (12%), or subclavian (4%) . During follow up, 198 of 205 AVACs were removed . The mean AVAC survival was superior (P < 0.0001, Fisher's protected least significant difference (PLSD) for tunnelled jugular AVACS (62 +/- 46 (SD) days) compared with simple jugular (20 +/- 19), subclavian (18 +/- 13) and femoral (7 +/- 6) . Causes for AVAC removal were: elective (47%), blockage (31%), infection (20%) or cracked catheter (1%) . Routine postremoval tip cultures grew coagulase negative Staphylococcus (CNS, 46%), negative culture (33%), methicillin-resistant Staphylococcus aureus (MRSA; 9%), Staphylococcus aureus (9%), Gram-negative rods (1%), Pseudomonas (0.5%) or other uncommon organisms (2%) . Blood cultures were drawn through the AVAC in the setting of suspected bacteraemia in 42 of 198 AVACs . Blood cultures were negative in 40% . Positive cultures included Staphylococcus species in 55%: including MRSA (19%), Staphylococcus aureus (29%) and CNS (34%) . Rare cultures identified Escherichia coli (2%) or Serratia (2%) . Infection and blockage significantly reduced AVAC survival, affecting more than 50% of cases . Approaches to minimize these complications are likely to lead to improved clinical outcomes with AVAC use.

J Soc Biol, 2003, 197(4), 375 - 8
{The nematode Caenorhabditis elegans as a model for the study of host-pathogen interactions}; Ewbank J; For certain pathogens capable of infecting a broad range of organisms, there exist universal virulence factors, necessary for full pathogenicity regardless of the host . This has been most clearly demonstrated by Ausubel and colleagues for the human opportunistic pathogen Pseudomonas aeruginosa . As a consequence, one can use non-mammalian model systems, including the nematode worm Caenorhabditis elegans, to assay for such virulence factors . A significant number of pathogens of C . elegans, that provoke a range of diseases, are now known, including the opportunistic human pathogen Serratia marcescens . After explaining the practical advantages associated with the use of C . elegans, and briefly reviewing previous studies, the results of a screen for S . marcescens virulence factors will be presented.

J Econ Entomol, 2004 Feb, 97(1), 74 - 8
Overwintering squash bugs harbor and transmit the causal agent of cucurbit yellow vine disease; Pair SD et al.; Since 1988, cucurbit crops, particularly watermelon, cantaloupe, and squash, grown in Oklahoma and Texas have experienced devastating losses from cucurbit yellow vine disease (CYVD), caused by the phloem-limited bacterium Serratia marcescens Bizio . Squash bug, Anasa tristis (De Geer), is a putative vector of the pathogen . In 2000-2001, overwintering populations of squash bug collected from DeLeon, TX, were tested for their ability to harbor and transmit the bacterium . Individual squash bugs (n = 73) were caged serially for periods of up to 7 d on at least four squash seedlings . Two studies were conducted, one with insects collected in November 2000 placed on first true leaf-stage seedlings and the second with insects from an April 2001 collection, placed on 3-5 true leaf-stage squash . Controls consisted of squash seedlings caged without insects . Squash bug transmission rates of the pathogen in studies I and II were 20 and 7.5%, respectively . Overall, 11.0% of the squash bugs harbored and successfully transmitted the bacterium to squash seedlings . All control plants tested negative for S . marcescens and did not exhibit CYVD . Female squash bugs killed a significantly greater proportion of young first leaf-stage seedlings than males . Feeding on 3-5 leaf-stage squash resulted in no plant mortality regardless of squash bug gender . This study demonstrated that the squash bug harbors S . marcescens in its overwintering state . The squash bug-S . marcescens overwintering relationship reported herein greatly elevates the pest status of squash bug and places more importance on development of integrated strategies for reducing potential overwintering and emerging squash bug populations.

Infect Control Hosp Epidemiol, 2004 Feb, 25(2), 156 - 61
Nosocomial Serratia marcescens outbreak in Osaka, Japan, from 1999 to 2000; Takahashi H et al.; OBJECTIVES: To investigate and control an outbreak of bloodstream infections (BSIs) caused by Serratia marcescens and to identify risk factors for respiratory colonization or infection with S . marcescens . DESIGN: Epidemiologic investigation, including review of medical and laboratory records, procedural investigations, pulsed-field gel electrophoresis (PFGE) typing of environmental and patient isolates, statistical study, and recommendation of control measures . PATIENTS AND SETTING: All patients admitted to a 380-bed, secondary-care hospital in Osaka Prefecture, Japan, from July 1999 through June 2000 (study period) . RESULTS: Seventy-one patients were colonized or infected with S . marcescens; 3 patients who developed primary BSIs on the same ward within 5 days in June 2000 had isolates with indistinguishable PFGE patterns and indwelling intravenous catheters for more than 5 days . On multivariate analysis, among 36 case-patients with positive sputum specimens and 95 control-patients, being bedridden (odds ratio {OR}, 15.91; 95% confidence interval {CI95}, 4.17-60.77), receiving mechanical ventilation (OR, 7.86; CI95, 2.27-27.16), being older than 80 years (OR, 3.12; CI95, 1.05-9.27), and receiving oral cleaning care (OR, 3.10; CI95, 1-9.58) were significant risk factors . S . marcescens was isolated from the fluid tanks of three nebulizers and a liquid soap dispenser . The hospital did not have written infection control standards, and many infection control practices were found to be inadequate (eg, respiratory equipment was used without disinfection between patients) . CONCLUSIONS: Poor hospital hygiene and the lack of standard infection control measures contributed to infections hospital-wide . Recommendations to the hospital included adoption of written infection control policies.

J Econ Entomol, 2003 Apr, 96(2), 272 - 9
The use of meconia to nondestructively detect sublethal infections in heliothines (Lepidoptera: Noctuidae); Inglis GD et al.; The utility of using meconia to nondestructively detect entomopathogens of lepidopterous heliothines was examined . Early-instar tobacco budworm {Heliothis virescens (F.)} or cotton bollworm {Helicoverpa zea (Boddie)} larvae were inoculated with cytoplasmic polyhedrosis virus (CPV), Serratia marcescens Bizio, or Nosema heliothidis Lutz and Splendor, and the presence of each of the entomopathogens in adults and the meconia discharged during adult eclosion was determined . As the dose of CPV occlusion bodies and N . heliothidis spores but not S . marcescens cells ingested by larvae increased, a greater number of both adults and meconia were infested with the entomopathogens . For all three entomopathogens, no difference was observed between males and females for any of the parameters tested . The accuracy of the meconium method for predicting the presence of the entomopathogens in the adults (i.e., number of individuals in which meconia and adults were both positive, or meconia and adults were both negative) was > or = 92% for CPV, and > or = 79% for S . marcescens and N . heliothidis . Very few false negative predictions (i.e., the meconium was negative but the adult was positive) were observed for CPV (< or = 1%) . The prevalence of false negative predictions ranged from 2 to 9%, and 5 to 21% for S . marcescens and N . heliothidis, respectively . The prevalence of false positive predictions (i.e., the meconium was positive but the adult was negative) was < or = 7% for CPV, < or = 13% for S . marcescens, and 0% for N . heliothidis . The results of this study demonstrate that although not absolute, the meconium method will be an efficacious method to detect nondestructively entomopathogens causing sublethal infections in heliothines, and possibly other insects, and thereby facilitate the rearing of specific pathogen free insects.

Biophys J, 2004 Mar, 86(3), 1863 - 70
Moving fluid with bacterial carpets; Darnton N et al.; We activated a solid-fluid interface by attaching flagellated bacteria to a solid surface . We adsorbed swarmer cells of Serratia marcescens to polydimethylsiloxane or polystyrene . The cell bodies formed a densely packed monolayer while their flagella continued to rotate freely . Motion of the fluid close to an extended flat surface, visualized with tracer beads, was dramatically enhanced compared to the motion farther away . The tracer beads revealed complex ever-changing flow patterns, some linear (rivers), others rotational (whirlpools) . Typical features of this flow were small (tens of micro m) and reasonably stable (many minutes) . The surface performed active mixing equivalent to diffusion with a coefficient of 2 x 10(-7) cm(2)/s . We call these flat constructs "bacterial carpets" . When attached to polystyrene beads or to fragments of polydimethylsiloxane, the bacteria generated both translation and rotation . We call these constructs "auto-mobile beads" or "auto-mobile chips" . Given the size and strength of the flow patterns near the carpets, the motion must be generated by small numbers of coordinated flagella . We should be able to produce larger and longer-range effects by increasing coordination.

Eur J Intern Med, 2003 Dec, 14(8), 501 - 503
Necrotic cellulitis by Serratia plymuthica; Pascual Perez R et al.; This case report describes an uncommon cellulitis caused by Serratia plymuthica in a patient treated with steroids . The evolution was favorable after surgical exploration with debridement and antibiotic treatment . This is the first case of necrotic cellulitis caused by S . plymuthica described in the literature.

World J Surg, 2004 Mar, 28(3), 242 - 6 Epub 2004 Feb 17.
Surgical site infections in breast surgery: case-control study; Vilar-Compte D et al.; The purpose of this study was to estimate the frequency of surgical site infections (SSIs) and identify associated risk factors for each type of breast surgery at a cancer hospital . We used a nested case-control design . Between February 1, 2000 and July 31, 2000, all breast surgeries performed were recorded on a daily basis . After hospital discharge, we evaluated patients simultaneously with surgeons three times a week for 30 days or longer . The odds ratio (OR) was estimated using logistic regression analysis . The study followed 280 patients (298 wounds) . Altogether, 77 SSIs were detected, for an overall SSI rate of 25.8% (77/298) . For excisions, conservative surgery, and radical mastectomies the SSI rates were 1.4%, 18.0%, and 38.3%, respectively . Excisions were excluded ( n = 68) for risk factor analysis . After multivariate analysis, risk factors associated with SSIs were obesity {OR 2.5, 95% confidence interval (CI) 1.2-4.3}, concomitant chemotherapy and radiation (OR 2.3, 95% CI 1.2-4.3), radical surgery (OR 3.1, 95% CI 1.1-8.6), insertion of a second drain during the late postoperative period (OR 3.7, 95% CI 1.8-7.8), and drainage duration > or = 19 days (OR 2.9, 95% CI 1.5-5.6) . The bacteria most frequently isolated were Pseudomonas aeruginosa ( n = 18 ), Serratia sp . ( n = 18), Staphylococcus aureus ( n = 10), and Staphylococcus epidermidis ( n = 10) . Poor compliance with infection control practices and wound management was detected throughout the study period . The overall frequency of SSIs for mastectomies was higher than the reported rates, which was principally related to the more radical surgery required for advanced-stage disease, preoperative irradiation, and inadequate wound and drain care.

Ophthalmologe, 2004 Jan, 101(1), 33 - 8
{Corneal infiltrates and ulcers . A retrospective study of 239 eyes}; Neumaier-Ammerer B et al.; PURPOSE: In our outpatient service the number of corneal infiltrates and ulcers associated with contact lens wear in young patients increased during the last years . Therefore we evaluated all patients with keratitis regarding to the reason . PATIENTS AND METHODS: From January 1999 to August 2000 the medical charts of 210 consecutive patients and 239 eyes were reviewed . We evaluated the percentage of contact lens wearers . Patient age, localisation and number of infiltrates, bacteria and healing results were also evaluated . RESULTS: In 134 of 239 eyes (56%) keratitis was caused by contact lenses, 127 eyes (53%) with soft lenses . The mean age of soft contact lens wearing patients was 28,2 +/-13,0 years . Mean age in other reasons was 46,0 +/-22,5 years . 71% (170 eyes) had single central infiltrates, 19% (45 eyes) multiple peripheral infiltrates and 10% (24 eyes) corneal ulcers . Bacteria were found in 33% (78 eyes) . The most frequent isolated bacteria in non contact lens induced keratitis was staphylococcus aureus (22 eyes) . In those eyes with soft contact lenses we found mostly gram negative bacteria such as serratia spp . (6 eyes), pseudomonas spp . (6 eyes), stenotrophomonas maltophilia (6 eyes) and klebsiella oxytoca (5 eyes) . 20% (26 of 127 eyes) of contact lens induced corneal infection healed with a scar . CONCLUSION: Our analysis shows, that the major part of keratitis was induced by soft contact lenses . One fifth of these very young patients retained a corneal scar . There is a higher risk to suffer a keratitis when using soft contact lenses . This should influence especially patients information regarding choice and use of soft contact lenses.

Exp Appl Acarol, 2003, 31(1-2), 105 - 13
Microanatomical and biological aspects of bacterial associations in Tyrophagus putrescentiae (Acari: Acaridida); Smrz J; The occurrence of bacterial colonies in the mesenchymal tissue of Tyrophagus putrescentiae Schrank was studied . One algal and two fungal species were offered as food . The experiment was analysed histologically and via transmission electron microscopy and plating of the mite homogenate . The dominant bacterium species, the bacterium population density in the mesenchyme, the location of bacterium groups between the internal organs and the ultrastructure were investigated . There were conspicuous differences between food types tested . On Penicillium, the highest population of bacteria in the mesenchymal tissue was correlated with the chitinase activity in mite homogenate . In this homogenate, Serratia marcescens was highly dominant among the other plated bacteria and it exhibited strong chitinolytic and trehalolytic activity.

Res Microbiol, 2004 Jan-Feb, 155(1), 25 - 30
Morphological and intracellular alterations induced by Serratia marcescens cytotoxin; Carbonell GV et al.; In the present work, in vitro assays were used to investigate the toxicity of Serratia marcescens cytotoxin in cultured Chinese hamster ovary (CHO) cells . The time necessary to detect cellular alterations such as the onset of apoptosis, the perturbation of mitochondrial function, and cytoskeletal changes was assessed . The internalization of the cytotoxin by CHO cells was also examined . Within 10-15 min of exposure to cytotoxin, CHO cells became round, the nucleus shrank, the chromatin became more compact, and cytoplasmic blebs appeared on the cell surface . TUNEL (TdT-mediated dUTP nick end labeling) and propidium iodide staining identified some nuclei with fragmented DNA, and electrophoresis of CHO cell DNA obtained after 30-min exposure to S . marcescens toxin showed a pattern of DNA fragments typically associated with apoptosis . The cells also lost their characteristic actin organization within 10 min of exposure to cytotoxin . Lactate dehydrogenase leakage was detected after 20-min exposure to the cytotoxin and increased with time thereafter . Concomitantly, there was a time-dependent reduction in mitochondrial activity . Fluorescein-labeled S . marcescens cytotoxin was detected only on the surface of CHO cells, even after 30-min exposure to the toxin.These results show that there was no internalization of the toxin by CHO cells, and that, once bound to the cell surface, the toxin was able to induce changes in intracellular metabolism and to trigger cell death by apoptosis.

Bioorg Khim, 2003 Nov-Dec, 29(6), 611 - 5
{Hydrolysis of phosphoether bonds of heme-independent chloride peroxidase from Serratia marcescens}; Preobrazhenskaia IuV et al.; Heme- and metal-independent chloroperoxidase from Serratia marcescens W 250 is shown to be capable of catalyzing the p-nitrophenyl phosphate hydrolysis . The parameters of the phosphatase reaction are determined and inhibitors and activators of the process are found . A hypothetical mechanism of the hydrolysis of phosphoesters by heme- and metal-independent haloperoxidases is suggested . The English version of the paper: Russian Journal of Bioorganic Chemistry, 2003, vol . 29, no . 6; see also http://www.maik.ru.

Neuroradiology, 2004 Feb, 46(2), 148 - 52 Epub 2004 Jan 16.
Brain abscesses after Serratia marcescens infection on a neonatal intensive care unit: differences on serial imaging; Messerschmidt A et al.; Serratia are known to be a possible cause of severe cerebral infections in neonates . We describe imaging of three premature infants infected with Serratia marcescens . Born in the 31( st), 25( th) and 28( th) weeks of gestation, they presented with signs of septicaemia on postnatal days 9, 24 and 32 . Initial sonography showed cysts in the first child, two areas with anechoic centre and echogenic rim in the second, and several echogenic areas in the third . Lesions were seen on CT, of low density in two cases and minimally increased density in the third . MRI in the first patient showed cysts with incomplete contrast enhancement of the lesions, while patient 2 showed five ring-enhancing fluid-containing lesions with thick walls . In the third patient two abscesses with contrast enhancement and several high-signal spots were seen . We discuss the pathophysiology of the lesions and the impact of the various imaging methods.

Biochim Biophys Acta, 2004 Jan 14, 1696(1), 103 - 11
Structure of the D142N mutant of the family 18 chitinase ChiB from Serratia marcescens and its complex with allosamidin; Vaaje-Kolstad G et al.; Catalysis by ChiB, a family 18 chitinase from Serratia marcescens, involves a conformational change of Asp142 which is part of a characteristic D(140)XD(142)XE(144) sequence motif . In the free enzyme Asp142 points towards Asp140, whereas it rotates towards the catalytic acid, Glu144, upon ligand binding . Mutation of Asp142 to Asn reduced k(cat) and affinity for allosamidin, a competitive inhibitor . The X-ray structure of the D142N mutant showed that Asn142 points towards Glu144 in the absence of a ligand . The active site also showed other structural adjustments (Tyr10, Ser93) that had previously been observed in the wild-type enzyme upon substrate binding . The X-ray structure of a complex of D142N with allosamidin, a pseudotrisaccharide competitive inhibitor, was essentially identical to that of the wild-type enzyme in complex with the same compound . Thus, the reduced allosamidin affinity in the mutant is not caused by structural changes but solely by the loss of electrostatic interactions with Asp142 . The importance of electrostatics was further confirmed by the pH dependence of catalysis and allosamidin inhibition . The pH-dependent apparent affinities for allosamidin were not correlated with k(cat), indicating that it is probably better to view the inhibitor as a mimic of the oxazolinium ion reaction intermediate than as a transition state analogue.

Eur J Biochem, 2004 Jan, 271(2), 253 - 62
Mutational and computational analysis of the role of conserved residues in the active site of a family 18 chitinase; Synstad B et al.; Glycoside hydrolysis by retaining family 18 chitinases involves a catalytic acid (Glu) which is part of a conserved DXDXE sequence motif that spans strand four of a (betaalpha)8 barrel (TIM barrel) structure . These glycoside hydrolases are unusual in that the positive charge emerging on the anomeric carbon after departure of the leaving group is stabilized by the substrate itself (the N-acetyl group of the distorted -1 sugar), rather than by a carboxylate group on the enzyme . We have studied seven conserved residues in the catalytic center of chitinase B from Serratia marcescens . Putative roles for these residues are proposed on the basis of the observed mutational effects, the pH-dependency of these effects, pKa calculations and available structural information . The results indicate that the pKa of the catalytic acid (Glu144) is 'cycled' during catalysis as a consequence of substrate-binding and release and, possibly, by a back and forth movement of Asp142 between Asp140 and Glu144 . Rotation of Asp142 towards Glu144 also contributes to an essential distortion of the N-acetyl group of the -1 sugar . Two other conserved residues (Tyr10 and Ser93) are important because they stabilize the charge on Asp140 while Asp142 points towards Glu144 . Asp215, lying opposite Glu144 on the other side of the scissile glycosidic bond, contributes to catalysis by promoting distortion of the -1 sugar and by increasing the pKa of the catalytic acid . The hydroxyl group of Tyr214 makes a major contribution to the positioning of the N-acetyl group of the -1 sugar . Taken together, the results show that catalysis in family 18 chitinases depends on a relatively large number of (partly mobile) residues that interact with each other and the substrate.

J Hosp Infect, 2004 Jan, 56(1), 29 - 36
A nosocomial outbreak of Serratia marcescens producing inducible Amp C-type beta-lactamase enzyme and carrying antimicrobial resistance genes within a class 1 integron; Bagattini M et al.; We investigated an outbreak of Serratia marcescens in the adult intensive care unit of the University Hospital of Napoli . The outbreak involved 13 cases of infection by S . marcescens over a nine-month period and was caused by a single pulsed-field gel electrophoresis clone . The epidemic strain was multiply antibiotic resistant, producing an inducible Amp C-type beta-lactamase enzyme and carrying the trimethoprim-resistance gene and the adenyltransferase gene, which confers resistance to streptomycin and spectinomycin, within a class 1 integron . Antimicrobial therapy with beta-lactams was associated with S . marcescens acquisition in the intensive care unit.

Med Dosw Mikrobiol, 2003, 55(3), 259 - 70
{Bacterial and fungal bloodstream infections in patients at the University Hospital of Cracow}; Kedzierska J et al.; In presented material evaluation of changes in sepsis and types of bloodstream infections of hospitalized patients in Wards of the University Hospital in Cracow were examined . Results of 9,138 blood cultures studied in years 1989-1999 were analysed . All of the blood samples were recovered from 4,656 infected adults at Clinics of the University Hospital in Cracow . Microbiological blood examinations were held in system of constant monitoring of isolated cultures applying BacT/Alert--colorimetric system (Organon Teknika) . Cultured micro--organisms were identified using commercial biochemical tests (bio-Merieux) . During period of research changes of profile of isolated microorganisms was observed . Percentage of blood infections of Enterococcus spp . etiology increased from 2.2% in 1989 to 9.8% in 1997-98 (p = 0.014) . Dynamic growth of non-fermentative S . maltophilia bacilli to 5.5% (p = 0.036) and Serratia marcescens to 13.8% (p = 0.042) in 1999 was revealed . Designed according to our research review of fungal flora in years 1989-1999 revealed tendency of systematic growth of invasive candidemia frequency, from 1.1% to 10.4% . Diagnostic and therapeutic profile of Departments was in a strict connection with increase of the number and meaning of the politiological bacteremias (p = 0.036) in total number of systemic infections cases.

Infect Immun, 2004 Jan, 72(1), 611 - 4
Activation of Serratia marcescens hemolysin through a conformational change; Walker G et al.; For Serratia marcescens, secreted hemolysin/cytotoxin is not only secreted but also activated by an outer membrane protein . Excluding posttranslational processing by mass spectrometry, the conformation of active and inactive ShlA derivatives strongly differed in electrophoretic mobilities, gel permeation chromatography, sensitivity to trypsin, circular dichroism, and intrinsic fluorescence . We concluded that ShlB interacts with ShlA during secretion and imposes a conformational change in ShlA to form the active hemolysin.

Carbohydr Res, 2003 Nov 14, 338(23), 2757 - 61
The structure of the polysaccharide part of the LPS from Serratia marcescens serotype O19, including linkage region to the core and the residue at the non-reducing end; Vinogradov E et al.; The structure of the LPS from Serratia marcescens serotype O19 was investigated . Deamination of the LPS released the O-chain polysaccharide together with a fragment of the core oligosaccharide . The following structure of the product was determined by NMR spectroscopy, mass spectrometry, and chemical methods: {carbohydrate structure: see text} The main polymer consists of a repeating disaccharide V-U and is present on average of 18 units per chain as estimated by integration of signals in the NMR spectra . The residue O corresponds to the primer, which initiates biosynthesis of the O-chain, and an oligomer of a disaccharide R-S is an insert between the primer and the main polymer . The polysaccharide has a beta-Kdo residue at the non-reducing end, a feature similar to that observed previously in the LPS from Klebsiella O12.

Int J Antimicrob Agents, 2003 Dec, 22(6), 601 - 6
The indirect pathogenicity of Stenotrophomonas maltophilia; Kataoka D et al.; Stenotrophomonas maltophilia has at least two inducible beta-lactamases, L1 and L2, which can hydrolyze almost all classes of beta-lactam antimicrobial agents . This study was done to verify the indirect pathogenicity of S . maltophilia that could promote the growth of other beta-lactam agent-susceptible bacteria in a mixed culture . We counted CFU of beta-lactam agent-susceptible bacteria under the presence of imipenem or ceftazidime in a pure culture and mixed culture with S . maltophilia . Our results showed that beta-lactamase leaking from S . maltophilia can encourage the growth of Serratia marcescens and Pseudomonas aeruginosa even if imipenem or ceftazidime was supplemented . This study discovered a blind spot in chemotherapy against an indirect pathogen such as S . maltophilia.

Proteins, 2003 Dec 1, 53(4), 908 - 16
The C-terminal module of Chi1 from Aeromonas caviae CB101 has a function in substrate binding and hydrolysis; Wang FP et al.; The chitinase gene chi1 of Aeromonas caviae CB101 encodes an 865-amino-acid protein (with signal peptide) composed of four domains named from the N-terminal as an all-beta-sheet domain ChiN, a triosephosphate isomerase (TIM) catalytic domain, a function-unknown A region, and a putative chitin-binding domain (ChBD) composed of two repeated sequences . The N-terminal 563-amino-acid segment of Chi1 (Chi1DeltaADeltaChBD) shares 74% identity with ChiA of Serratia marcescens . By the homology modeling method, the three-dimensional (3D) structure of Chi1DeltaADeltaChBD was constructed . It fit the structure of ChiA very well . To understand fully the function of the C-terminal module of Chi1 (from 564 to 865 amino acids), two different C-terminal truncates, Chi1DeltaChBD and Chi1DeltaADeltaChBD, were constructed, based on polymerase chain reaction (PCR) . Comparison studies of the substrate binding, hydrolysis capacity, and specificity among Chi1 and its two truncates showed that the C-terminal putative ChBD contributed to the insoluble substrate-protein binding and hydrolysis; the A region did not have any function in the insoluble substrate-protein binding, but it did have a role in the chitin hydrolysis: Deletion of the A region caused the enzyme to lose 30-40% of its activity toward amorphous colloidal chitin and soluble chitin, and around 50% toward p-nitrophenyl (pNP)-chitobiose pNP-chitotriose, and its activity toward low-molecular-weight chitooligomers (GlcNAc)3-6 also dropped, as shown by analysis of its digestion processes . This is the first clear demonstration that a domain or segment without a function in insoluble substrate-chitinase binding has a role in the digestion of a broad range of chitin substrates, including low-molecular-weight chitin oligomers . The reaction mode of Chi1 is also described and discussed .

Protein Eng, 2003 Nov, 16(11), 841 - 6
Stabilization of a chitinase from Serratia marcescens by Gly-->Ala and Xxx-->Pro mutations; Gaseidnes S et al.; This paper describes attempts to increase the kinetic stability of chitinase B from Serratia marcescens (ChiB) by the introduction of semi-automatically designed rigidifying mutations of the Gly-->Ala and Xxx-->Pro type . Of 15 single mutants, several displayed significant increases in thermal stability, whereas most mutants showed minor effects . All mutations with non-marginal effects on stability clustered in a limited, surface-exposed region of the enzyme, indicating that this region is involved in a partial unfolding process that triggers irreversible thermal inactivation (aggregation) . A double mutant containing two stabilizing mutations in this region (G188A, A234P) displayed a 10-fold increase in half-life at 57 degrees C and a 4.2 degrees C increase in apparent T(m) . These results show that entropic stabilization works well for ChiB and they pinpoint a region whose unfolding may be crucial for the kinetic stability of this enzyme.

Jpn J Thorac Cardiovasc Surg, 2003 Oct, 51(10), 511 - 4
Management with closed irrigation for post-sternotomy mediastinitis: experience with the use of electrolyzed strong acid aqueous solution; Ohuchi S et al.; OBJECTIVE: The aim of this study was to assess the adequacy of our treatment strategy for patients with post-sternotomy mediastinitis . METHODS: Between May 1997 and December 2000, 1,045 consecutive adult cardiac operations were performed at our center . Mediastinitis occurred in 8 patients (0.77%) and as treatment, they underwent (1) aggressive debridement, (2) closed irrigation and drainage, and (3) transvenous administration of antibiotics . We irrigated the mediastinum with 0.1-1.0% povidone-iodine solution, alternating with electrolyzed strong acid aqueous solution . We subsequently reviewed the outcome after the closed irrigation treatment for patients with post-sternotomy mediastinitis . RESULTS: In four of the 8 patients, the culture specimen grew Methicillin-resistant Staphylococcus aureus . In the others, Serratia marcescens, Staphylococcus epidermidis, Pseudomonas aeruginosa and Gram-negative rods were cultured . The mean period between primary surgery and the diagnosis of mediastinitis was 16.3 (8 -57) days . The mean period between diagnosis of mediastinitis and the start of the irrigation treatment was 0.8 (0-3) days . The mean irrigation period was 30.0 (14-47) days . The irrigation complications were mild hepatic dysfunction in 2 patients, hyponatremia in 2 and protracted wound infection in 1 . The hospital mortality was 1/8 (12.5%) . Seven survivors are free from recurrent mediastinitis . CONCLUSIONS: Our experience of closed irrigation and drainage suggests that it can yield satisfactory results after post-sternotomy mediastinitis, comparable to other reported results with or without muscle flaps.

J Biol Chem, 2004 Jan 30, 279(5), 3612 - 9 Epub 2003 Nov 03.
Interactions of a family 18 chitinase with the designed inhibitor HM508 and its degradation product, chitobiono-delta-lactone; Vaaje-Kolstad G et al.; We describe enzymological and structural analyses of the interaction between the family 18 chitinase ChiB from Serratia marcescens and the designed inhibitor N,N'-diacetylchitobionoxime-N-phenylcarbamate (HM508) . HM508 acts as a competitive inhibitor of this enzyme with a K(i) in the 50 microM range . Active site mutants of ChiB show K(i) values ranging from 1 to 200 microM, providing insight into some of the interactions that determine inhibitor affinity . Interestingly, the wild type enzyme slowly degrades HM508, but the inhibitor is essentially stable in the presence of the moderately active D142N mutant of ChiB . The crystal structure of the D142N-HM508 complex revealed that the two sugar moieties bind to the -2 and -1 subsites, whereas the phenyl group interacts with aromatic side chains that line the +1 and +2 subsites . Enzymatic degradation of HM508, as well as a Trp --> Ala mutation in the +2 subsite of ChiB, led to reduced affinity for the inhibitor, showing that interactions between the phenyl group and the enzyme contribute to binding . Interestingly, a complex of enzymatically degraded HM508 with the wild type enzyme showed a chitobiono-delta-lactone bound in the -2 and -1 subsites, despite the fact that the equilibrium between the lactone and the hydroxy acid forms in solution lies far toward the latter . This shows that the active site preferentially binds the (4)E conformation of the -1 sugar, which resembles the proposed transition state of the reaction.

Microb Ecol, 2004 Feb, 47(2), 133 - 6 Epub 2004 Mar 04.
Microbial characterization of free floating condensate aboard the Mir space station; Ott CM et al.; Three samples of humidity condensate that had accumulated behind panels aboard the Russian space station Mir were collected and returned to earth for analysis . As these floating masses of liquid come into contact with the astronauts and the engineering systems, they have the potential to affect both crew health and systems performance . Using a combination of culturing techniques, a wide variety of organisms were isolated included Escherichia coli, Serratia marcescens, and a presumed Legionella species . In addition, microscopic analysis indicated the presence of protozoa, dust mites, and spirochetes . These findings suggest the need for more comprehensive microbial analysis of the environment through the use of new methodologies to allow a more thorough risk assessment of spacecraft .

Arch Med Res, 2003 May-Jun, 34(3), 237 - 41
An outbreak due to Serratia marcescens in a neonatal intensive care unit typed by 2-day pulsed field gel electrophoresis protocol; Miranda-Novales G et al.; BACKGROUND: Serratia marcescens is a well-recognized nosocomial pathogen . The objective of the study was to describe typing results using a rapid pulsed field gel electrophoresis (PFGE) protocol and infection control measures during an outbreak of Serratia marcescens in a 24-bed, referral, neonatal intensive care unit (NICU) of a tertiary-care pediatric hospital . METHODS: Two patients with S . marcescens sepsis were identified in the NICU . Health care personnel of the unit were requested to reinforce infection control measures . Active surveillance was established to detect infected and/or colonized patients and environmental and staff reservoirs . Infected and colonized patients were cohorted on one side of the unit; admissions to NICU were limited . Isolates were typed with a short 2-day pulsed-field gel electrophoresis (PFGE) protocol . RESULTS: Thirty three patients were exposed during a period of 20 days . Ten S . marcescens isolates were obtained from six patients, in two from blood culture and in three from stool culture; a single clone was identified in four . S . marcescens was not isolated from environmental or staff cultures . CONCLUSIONS: PFGE results were obtained in 2 days, infection control measures were reinforced, outbreak was promptly interrupted, and the NICU remained opened.

FEMS Immunol Med Microbiol, 2003 Oct 15, 38(3), 241 - 8
Evaluation and comparison of random amplification of polymorphic DNA, pulsed-field gel electrophoresis and ADSRRS-fingerprinting for typing Serratia marcescens outbreaks; Krawczyk B et al.; Amplification of DNA fragments surrounding rare restriction sites (ADSRRS-fingerprinting) is a novel assay based on suppression of polymerase chain reaction (PCR) . This phenomenon allows the amplification of only a limited subset of DNA fragments, since only those with two different oligonucleotides ligated at the ends of complementary DNA strands are amplified in the PCR . The DNA fragments can be easily analyzed on polyacrylamide gels, stained with ethidium bromide . We have implemented this method using a set of clinical Serratia marcescens isolates from three outbreaks ongoing in the Public Hospital in Gdansk (Poland) . Clustering of ADSRRS-fingerprinting data matched epidemiological, microbiological, random amplification of polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) data . Based on this study, we found that there is at least a similar power of discrimination between the present 'gold-standard' PFGE and the novel method, ADSRRS-fingerprinting . Although the ADSRRS-fingerprinting method may appear to be more complex than the RAPD technique, we found it fast and reproducible.

Mol Microbiol, 2003 Oct, 50(1), 77 - 88
Ligand delivery by haem carrier proteins: the binding of Serratia marcescens haemophore to its outer membrane receptor is mediated by two distinct peptide regions; Letoffe S et al.; Haem is involved in essential processes . It is toxic and thus is not found free in living organisms but almost entirely sequestered by haem carrier proteins . We investigated the mechanisms of haem transfer between the proteins of a bacterial haem acquisition system involving haemophores . Haemophores are secreted by several Gram-negative bacteria and are able to extract haem (assimilated as an iron source) from haemoproteins and deliver it to specific outer membrane receptors . The Serratia marcescens haemophore (HasA) is folded into a globular form and tyrosine and histidine are involved in haem ligation . Interaction with the receptor is of high affinity (5 nM) and does not involve haem . Identification and study of mutants with altered binding properties led to the description of two regions of the haemophore that bind to the receptor . They consist of residues involved in two beta strands located on the same side of HasA . Each region is sufficient for high affinity binding . The synthetic peptide corresponding to one beta strand competes with the corresponding haemophore region for binding to the receptor, suggesting that the two binding regions are independent binding sites . We propose a model for haem release and transfer to the receptor.

Biochemistry, 2003 Sep 16, 42(36), 10627 - 33
Thermodynamics of heme binding to the HasA(SM) hemophore: effect of mutations at three key residues for heme uptake; Deniau C et al.; HasA(SM) secreted by the Gram-negative bacterium Serratia marcescens belongs to the hemophore family . Its role is to take up heme from host heme carriers and to shuttle it to specific receptors . Heme is linked to the HasA(SM) protein by an unusual axial ligand pair: His32 and Tyr75 . The nucleophilic nature of the tyrosine is enhanced by the hydrogen bonding of the tyrosinate to a neighboring histidine in the binding site: His83 . We used isothermal titration microcalorimetry to examine the thermodynamics of heme binding to HasA(SM) and showed that binding is strongly exothermic and enthalpy driven: DeltaH = -105.4 kJ x mol(-1) and TDeltaS = -44.3 kJ x mol(-1) . We used displacement experiments to determine the affinity constant of HasA(SM) for heme (K(a) = 5.3 x 10(10) M(-1)) . This is the first time that this has been reported for a hemophore . We also analyzed the thermodynamics of the interaction between heme and a panel of single, double, and triple mutants of the two axial ligands His32 and Tyr75 and of His83 to assess the implication of each of these three residues in heme binding . We demonstrated that, in contrast to His32, His83 is essential for the binding of heme to HasA(SM), even though it is not directly coordinated to iron, and that the Tyr75/His83 pair plays a key role in the interaction.

Microb Drug Resist, 2003 Fall, 9(3), 257 - 64
The role of Serratia marcescens porins in antibiotic resistance; Ruiz N et al.; The outer membrane permeability of Serratia marcescens was studied by comparing porin-deficient mutants with their parental strains . Omp1-deficient strains were selected by moxalactam resistance, whereas mutants lacking the Omp2 porin were obtained by experimental infection with the SMP2 phage, whose primary receptor is the Omp2 porin . The role of porins was demonstrated in quinolone accumulation assays, where semiquantitative differences in accumulation were observed . Permeability coefficients to cephaloridine of Omp1 mutants were determined and compared with those of the parental strain . The clinical isolates S . marcescens HCPR1 and 866 showed 30- to 200-fold reduced permeability coefficients when Omp1 porin was absent.

J Ind Microbiol Biotechnol, 2003 Oct, 30(10), 593 - 8 Epub 2003 Aug 30.
Production of palatinose using Serratia plymuthica cells immobilized in chitosan; Krastanov A et al.; In recent decades, the production of palatinose has aroused great interest since this structural isomer of sucrose has interesting potential . We describe a simple and effective method of immobilizing Serratia plymuthica cells in chitosan . The sucrose isomerase activity of immobilized preparations was enhanced many times by activation with fresh nutrient medium and subsequent drying . The preparations obtained were physically very stable with high enzyme activity and excellent operational stability . The effect of temperature, pH and substrate concentration on enzyme activity of the immobilized cells was investigated . Using immobilized cells, a complete conversion of sucrose (40% solution) into palatinose was achieved in 4 h in a "batch"-type enzyme reactor . The use of free or immobilized cells had no effect on the composition of the solution, in particular the sugar content . The palatinose content was 80% and that of trehalulose 7%.

Antimicrob Agents Chemother, 2003 Sep, 47(9), 2897 - 902
The aminoglycoside 6'-N-acetyltransferase type Ib encoded by Tn1331 is evenly distributed within the cell's cytoplasm; Dery KJ et al.; The multiresistance transposon Tn1331, which mediates resistance to several aminoglycosides and beta-lactams, includes the aac(6')-Ib, aadA1, bla(OXA-9), and bla(TEM-1) genes . The nucleotide sequence of aac(6')-Ib includes a region identical to that of the bla(TEM-1) gene . This region encompasses the promoter and the initiation codon followed by 15 nucleotides . Since there were three possible translation initiation sites, the amino acid sequence at the N terminus of the aminoglycoside 6'-N-acetyltransferase type Ib {AAC(6')-Ib} was determined and was found to be SIQHF . This result indicated that aac(6')-Ib includes a translational fusion: the first five amino acids of the leader peptide of the TEM beta-lactamase are fused to the rest of the AAC(6')-Ib protein . This gene fusion could have formed during the genesis of Tn1331 as a consequence of the generation of a 520-nucleotide duplication (M . E . Tolmasky, Plasmid 24:218-226, 1990) . An identical gene isolated from a Serratia marcescens strain has been previously described (G . Tran van Nhieu and E . Collatz, J . Bacteriol . 169:5708-5714, 1987) . Extraction of the periplasmic proteins of E . coli harboring aac(6')-Ib by spheroplast formation showed that most of the AAC(6')-Ib protein is present in the cytoplasm . A genetic fusion to phoA confirmed these results . AAC(6')-Ib was shown to be evenly distributed inside the cell's cytoplasm by fluorescent microscopy with an AAC(6')-Ib-cyan fluorescent protein fusion.

Carbohydr Res, 2003 Sep 1, 338(18), 1823 - 33
Enhanced enzymatic hydrolysis of langostino shell chitin with mixtures of enzymes from bacterial and fungal sources; Donzelli BG et al.; A combination of enzyme preparations from Trichoderma atroviride and Serratia marcescens was able to completely degrade high concentrations (100 g/L) of chitin from langostino crab shells to N-acetylglucosamine (78%), glucosamine (2%), and chitobiose (10%) . The result was achieved at 32 degrees C in 12 days with no pre-treatment (size reduction or swelling) of the substrate and without removal of the inhibitory end-products from the mixture . Enzymatic degradation of three forms of chitin by Serratia/Trichoderma and Streptomyces/Trichoderma blends was carried out according to a simplex-lattice mixture design . Fitted polynomial models indicated that there was synergy between prokaryotic and fungal enzymes for both hydrolysis of crab chitin and reduction of turbidity of colloidal chitin (primarily endo-type activity) . Prokaryotic/fungal enzymes were not synergistic in degrading chitosan . Enzymes from prokaryotic sources had much lower activity against chitosan than enzymes from T . atroviride.

Biochem J, 2003 Nov 15, 376(Pt 1), 87 - 95
Family 18 chitinase-oligosaccharide substrate interaction: subsite preference and anomer selectivity of Serratia marcescens chitinase A; Aronson NN Jr et al.; The sizes and anomers of the products formed during the hydrolysis of chitin oligosaccharides by the Family 18 chitinase A (ChiA) from Serratia marcescens were analysed by hydrophilic interaction chromatography using a novel approach in which reactions were performed at 0 degrees C to stabilize the anomer conformations of the initial products . Crystallographic studies of the enzyme, having the structure of the complex of the ChiA E315L (Glu315-->Leu) mutant with a hexasaccharide, show that the oligosaccharide occupies subsites -4 to +2 in the substrate-binding cleft, consistent with the processing of beta-chitin by the release of disaccharide at the reducing end . Products of the hydrolysis of hexa- and penta-saccharides by wild-type ChiA, as well as by two mutants of the residues Trp275 and Phe396 important in binding the substrate at the +1 and +2 sites, show that the substrates only occupy sites -2 to +2 and that additional N -acetyl-D-glucosamines extend beyond the substrate-binding cleft at the reducing end . The subsites -3 and -4 are not used in this four-site binding mode . The explanation for these results is found in the high importance of individual binding sites for the processing of short oligosaccharides compared with the cumulative recognition and processive hydrolysis mechanism used to digest natural beta-chitin.

Biochem Biophys Res Commun, 2003 Sep 5, 308(4), 770 - 6
Immunodominance of conformation-dependent B-cell epitopes of protein antigens; Ito HO et al.; Immunodominance of conformational epitopes over linear ones in four proteins was quantified making use of the B-cell hybridoma technology . The proteins were immunized in their native forms into BALB/c mice, and clonal frequencies of B-cell hybridomas that produce antibodies to the native and denatured forms were determined, using ELISA and immunoblotting . All 16 monoclonal antibodies (mAbs) to Porphyromonas gingivalis fimbria were suggested to recognize conformational epitopes expressed by the oligomer . Ten out of 14 mAbs to Serratia marcescens fimbria and 13 of 15 mAbs to hen lysozyme were also specific to their conformational epitopes . In contrast, all 18 mAbs to a surface protein of Streptococcus mutans, termed PAc, reacted to both the native and denatured forms, thereby indicating the immunodominance of linear epitopes in this protein . The results suggest that B-cell epitopes of proteins possessing stable tertiary or quaternary structures are predominantly expressed by the higher-order structures.

Arzneimittelforschung, 2003, 53(7), 526 - 31
Synthesis, degradation kinetics and in vitro antimicrobial activity of tetrahydro-2H-1,3,5-thiadiazine-2-thione derivatives of some beta-amino acids; Aboul-Fadl T et al.; Two series of tetrahydro-2H-1,3,5-thiadiazine-2-thione (THTT) derivatives were synthesized, 2a-f and 3a-f, by incorporation of beta-alanine and beta-phenylalanine, respectively, at the 5th position of the THTT moiety . Structures of these derivatives were verified by spectral and elemental methods of analyses . The lipophilic properties of the synthesized derivatives, expressed as calculated log P (Clog P), revealed that the beta-phenylalanine derivatives, 3a-f, have enhanced lipophilic characters compared to the corresponding beta-alanine analogues, 2a-f . The stability of the synthesized derivatives in aqueous buffer solution of pH 7.4, and in 80% human plasma was studied at 37 degrees C using high pressure liquid chromatography . As a general pattern, under the investigation conditions beta-phenylalanine derivatives were more labile and susceptible for chemical and enzymatic degradation than the corresponding beta-alanine analogues . Furthermore, the degradation rates of the synthesized derivatives affected by the variation of substituents on N-3 of the THTT moiety . The anti-fungal activity of the synthesized compounds was tested in vitro against different strains of fungi using the standard agar disk diffusion method . beta-Alanine derivatives, 2e and 2f, bearing an aralkyl group on the 3ed position of the THTT moiety exhibited antifungal activity against C . albicans and F . oxysporum . Furthermore, 2a, which is also a beta-alanine derivative bearing an ethyi group on the 3ed position of the THTT moiety solely showed a significant in vitro anti-bacterial activity against Bacillus serreus (Gram positive) and Serratia rhodnii (Gram negative).

J Clin Microbiol, 2003 Aug, 41(8), 3986 - 8
Severe Serratia liquefaciens sepsis following vitamin C infusion treatment by a naturopathic practitioner; Engelhart S et al.; A 66-year-old female patient developed severe Serratia liquefaciens sepsis following vitamin C infusion treatment by a naturopathic practitioner . The clinical course of the infection was characterized by several complications, and the direct costs of the hospital stay amounted to about 40000 Euro . Genotypically identical S . liquefaciens was isolated from the residue of the infusate given to the patient, as well as from the washbasin overflow and from two other infusion bottles . A careful inspection of the dispensing facilities and review of procedures used to prepare the infusate revealed several indications of poor hygiene . However, the source of contamination could not be fully clarified . This case report raises questions about the local facilities and personal qualifications required for naturopathic practitioners to conduct invasive procedures and demonstrates that lapses in hygiene can lead to severe morbidity and high cost.

Plast Reconstr Surg, 2003 Aug, 112(2), 467 - 76
Infectious complications following breast reconstruction with expanders and implants; Nahabedian MY et al.; The incidence of infection following breast reconstruction with expanders and implants ranges from 1 to 24 percent . Numerous factors associated with infection have been described; however, a one-variable at time setting and multifactorial analysis have not been performed . The purpose of this study was to analyze a set of factors that may predispose women to infection of the expander or implant . Between 1997 and 2000, a total of 168 implant reconstructions were performed in 130 women at a single institution . The mean age for all women was 48.2 years (range, 25 to 77 years) . The factors that were analyzed included axillary lymph node dissection, chemotherapy, radiation therapy, tumor stage, timing of implant insertion, number of sides (unilateral versus bilateral), tobacco use, and presence or absence of diabetes mellitus . Statistical analysis was performed with stepwise logistic regression . Mean time to follow-up for all patients was 29 months (range, 12 to 47 months) . Infectious complications occurred in 10 women (7.7 percent) and in 10 expanders or implants (5.9 percent) . Infected implants were removed an average of 116 days following insertion (range, 14 to 333 days) . Cultured bacteria included Staphylococcus aureus and Serratia marcescens . A significant association (p < 0.04) was detected between implant infection and radiation therapy . The chance for implant infection was 4.88 times greater for implants that were exposed to radiation therapy compared with those that were not . In addition, there was suggestive (p < 0.09) evidence that the chance of implant infection following lymph node dissection was 6.29 times higher than when no lymph nodes were removed . No significant association between implant infection and age, diabetes, tobacco use, tumor stage, timing of implant insertion, or chemotherapy was found.

Can J Microbiol, 2003 May, 49(5), 305 - 12
Bacterial extracellular protease activities in field soils under different fertilizer managements; Watanabe K et al.; The major extracellular endopeptidase from Bacillus subtilis PF212 (isolated from paddy field soil) and B . subtilis CF80 (isolated from upland field soil) belongs to the group of serine proteases produced by Bacillus spp . known as subtilisins (optimum pH 7.0, optimum temperature 60 degrees C, and molecular mass 28 kDa) . The NH2-terminal amino acid sequence (20 amino acids) of the endopeptidase from (i) strain CF80 was identical with that of subtilisin BPN' and (ii) strain PF212 was identical with that of subtilisin Amylosacchariticus . The properties (i.e., effect of inhibitors) of these endopeptidases were similar to those of the overall soil endopeptidase and soil endopeptidases extracted from paddy field soil . From the numbers of B . subtilis we isolated from paddy fields and found to produce a subtilisin-like serine protease, it seemed possible to consider that subtilisin was one of the soil endopeptidases in paddy field soils . The major extracellular endopeptidase from Serratia marcescens (strains 4-12-132, 4-12-131, and 4-60-110) isolated from upland field soils applied with animal slurry is a serratial metalloprotease (optimum pH 9.5, optimum temperature 40 degrees C, and molecular mass 50 kDa) . The NH2-terminal amino acid sequence (20 amino acids) of the endopeptidase from strain 4-12-132 was identical with that of serratial metalloprotease, and partial DNA sequence of the endopeptidase gene of S . marcescens 4-12-132 had high homology with that of the serratial metalloprotease gene . The properties (i.e., effect of inhibitors) of this endopeptidase were similar to those of the overall soil endopeptidase in upland fields applied with animal slurry . Thus, it was possible to consider that serratial metalloprotease was one of the soil endopeptidases in upland fields applied with animal slurry.

J Am Acad Dermatol, 2003 Aug, 49(2 Suppl Case Reports), S193 - 4
Spontaneous dermal abscesses and ulcers as a result of Serratia marcescens; Friedman ND et al.; Serratia sp have only rarely been reported as isolates from leg ulcers . We describe the case of a middle-aged man with a medical history significant for alcohol-induced cirrhosis who presented with rapidly progressive skin ulcers initially starting as purple nodules . These skin ulcers and underlying dermal abscesses were found to be a result of S marcescens, with the presumed portal of entry being a toe-web infection.

Arch Biochem Biophys, 2003 Aug 15, 416(2), 147 - 54
Novel inhibitor for prolyl aminopeptidase from Serratia marcescens and studies on the mechanism of substrate recognition of the enzyme using the inhibitor; Inoue T et al.; Prolyl aminopeptidase from Serratia marcescens hydrolyzed x-beta-naphthylamides (x=prolyl, alanyl, sarcosinyl, L-alpha-aminobutylyl, and norvalyl), which suggested that the enzyme has a pocket for a five-member ring . Based on the substrate specificity, novel inhibitors of Pro, Ala, and Sar having 2-tert-butyl-{1,3,4}oxadiazole (TBODA) were synthesized . The K(i) value of Pro-TBODA, Ala-TBODA, and Sar-TBODA was 0.5 microM, 1.6 microM, and 12mM, respectively . The crystal structure of enzyme-Pro-TBODA complex was determined . Pro-TBODA was located at the active site . Four electrostatic interactions were located between the enzyme and the amino group of Pro inhibitors (Glu204:0E1-N:Inh, Glu204:0E2-N:Inh, Glu232:0E1-N:Inh, and Gly46:O-N:Inh), and the residue of the inhibitors was inserted into the hydrophobic pocket composed of Phe139, Leu141, Leu146, Tyr149, Tyr150, and Phe236 . The roles of Phe139, Tyr149, and Phe236 in the hydrophobic pocket and Glu204 and Glu232 in the electrostatic interactions were confirmed by site-directed mutagenesis, which indicated that the molecular recognition of proline is achieved through four electrostatic interactions and an insertion in the hydrophobic pocket of the enzyme.

Int J Syst Evol Microbiol, 2003 Jul, 53(Pt 4), 1013 - 8
Zooshikella ganghwensis gen . nov., sp . nov., isolated from tidal flat sediments; Yi H et al.; Two red pigment-producing bacterial strains with a metallic green sheen were isolated from a sediment sample of getbol, the Korean tidal flat . Phylogenetic analysis based on 16S rDNA sequences showed that these isolates represent a phyletic lineage within the gamma-Proteobacteria that is distantly related to the genus Hahella . No bacterial species with validly published names showed > or = 92% 16S rRNA similarity with the getbol isolates . The strains were gram-negative, chemo-organotrophic, aerobic and required NaCl (1-7%) for growth . They produced pigments with maximum absorption at 540 nm, which indicated the presence of prodigiosin, a well-known red pigment previously detected in Serratia marcescens . The major isoprenoid quinone was ubiquinone-9 . The predominant cellular fatty acids were saturated and monounsaturated straight-chain fatty acids . The DNA G + C contents ranged from 40 to 42 mol% . The combination of physiological, biochemical and chemotaxonomic data clearly separated the test strains from other phylogenetically related genera in the gamma-Proteobacteria . On the basis of polyphasic evidence from this study, it is proposed that the two getbol isolates should be classified in a novel genus, Zooshikella gen . nov., as Zooshikella ganghwensis sp . nov.

Zh Mikrobiol Epidemiol Immunobiol, 2003 May-Jun, (3), 11 - 5
{Cultivation of microorganisms in micro-volumes of culture media}; Davydkin VIu et al.; Studies on the cultivation of aerobic microorganisms in microdrops of growth medium, immobilized in a layer of highly dispersed disconnector (Aerosil), were carried out . The dispersion of the growth medium and its immobilization in a layer of Aerosil was found to produce no influence on the morphological, cultural and biochemical properties of Serratia marcescens cells, determined both immediately after treatment with the field and some time after storage of the treated suspensions . On the contrary, the duration of the action of ferromagnetic bodies produced essential influence on the viability of the microorganisms in dispersed growth medium and on the accumulation of cells in the course of subsequent cultivation . The development of cells grown in the microdrops of the nutriuent medium was similar to that of cells grown in submerged cultivation, following the S-shaped curve . With the increase of the seed dose a drop in the initial growth rate occurred and the accumulation of microbial cells increased by the end of the process . The greatest increase of biomass was observed with minimal seed doses . With a rise in the concentration of amino nitrogen in the growth medium the yield of cells increased only till this concentration reached 320 mg% . Under these conditions the specific growth rate also increased . The accumulation of cells was greater and occurred earlier when microorganisms were cultivated in immobilized state in powder.

Biotechnol Lett, 2003 Feb, 25(3), 191 - 7
Molecular characterization of polyphosphate kinase (ppk) gene from Serratia marcescens; Lee SJ et al.; To understand the mechanism of phosphate accumulation, a gene encoding polyphosphate kinase (PPK) was cloned from the genomic library of Serratia marcescens by Southern hybridization . From the nucleotide sequence of a 4 kb DNA fragment, an open reading frame of 2063 nucleotides was identified encoding a protein of 686 amino acids with molecular mass of 70 kDa . The potential CRP binding site and pho box sequence were found upstream of the putative promoter in the regulatory region . The expression of PPK resulted in the formation of inclusion bodies and the product was active at low temperature . The E . coli strain harboring plasmid pSPK5 with ppk gene increased enzyme activity of polyphosphate kinase, resulting in increased accumulation of polyphosphate in E . coli.

Insect Biochem Mol Biol, 2003 Aug, 33(8), 749 - 59
A Bombyx mori gene, BmChi-h, encodes a protein homologous to bacterial and baculovirus chitinases; Daimon T et al.; We have cloned and characterized a novel chitinase gene (BmChi-h) from the silkworm, Bombyx mori . BmChi-h cDNA has an open reading frame of 1,665 nucleotides, encoding a protein of 555 amino acid residues . The predicted protein shared extensive similarities with bacterial and baculovirus chitinases in both amino acid sequences (73% identity with Serratia marcescens chiA and 63% with Autographa californica nucleopolyhedrovirus chiA) and domain architectures . BmChi-h was a single-copy gene and located on chromosome 7 . The expression of BmChi-h mRNA was observed in a stage- and tissue-specific manner that was almost identical to that of another chitinase gene previously cloned from B . mori . We further determined the overall genomic organization of BmChi-h . There was no intron in the ORF of BmChi-h . However, BmChi-h was transcribed from three promoters, which generated three isoforms in the 5'-UTR of the transcript . Phylogenetic analysis suggested that ancestral species of B . mori acquired the chitinase gene from a bacterium or an ancestral baculovirus via horizontal gene transfer.

J Am Chem Soc, 2003 Jul 16, 125(28), 8486 - 93
Carbapenem biosynthesis: confirmation of stereochemical assignments and the role of CarC in the ring stereoinversion process from L-proline; Stapon A et al.; (5R)-Carbapen-2-em-3-carboxylic acid is the simplest structurally among the naturally occurring carbapenem beta-lactam antibiotics . It co-occurs with two saturated (3S,5S)- and (3S,5R)-carbapenam carboxylic acids . Confusion persists in the literature about the signs of rotation and absolute configurations of these compounds that is resolved in this paper . (3S,5S)-Carbapenam carboxylic acid was prepared from L-pyroglutamic acid to unambiguously establish its absolute configuration as identical to the natural product isolated from Serratia marcescens and from overexpression of the biosynthetic genes carAB in Escherichia coli . L-Proline labeled with deuterium or tritium at the diastereotopic C-5 methylene loci was shown to incorporate one label at the bridgehead of (3S,5S)-carbapenam carboxylic acid, but not into the "inverted" (3S,5R)-carbapenam carboxylic acid or the final carbapenem product . CarC, the third enzyme of the biosynthetic pathway required to synthesize the carbapenem, was demonstrated in cell-free studies to be dependent on alpha-ketoglutarate and ascorbate in keeping with weak sequence identities with other non-heme iron, alpha-ketoglutarate-dependent oxygenases . CarC mediated the stereoinversion of synthetic (3S,5S)-carbapenam carboxylic acid to the (5R)-carbapenem as judged by bioassay . These findings suggest that L-proline is desaturated to pyrroline-5-carboxylic acid prior to uptake into the biosynthetic pathway . The loss of the bridgehead hydrogen from the (3S,5S)-carbapenam during the ring inversion process to form the epimeric (3S,5R)-carbapenam and desaturation to the (5R)-carbapenem are proposed to be coupled by CarC to the reduction of dioxygen to drive the formation of these higher energy products, an unprecedented reaction for this enzyme class.

J Pharm Pharmacol, 2003 Jun, 55(6), 735 - 40
Restoration of antibacterial activity of beta-lactams by epigallocatechin gallate against beta-lactamase-producing species depending on location of beta-lactamase; Zhao WH et al.; The combined effects of (-)-epigallocatechin gallate (EGCg) and beta-lactams were investigated against various beta-lactamase-producing clinical isolates, including 21 Staphylococcus aureus, 6 Escherichia coli, 3 Klebsiella pneumoniae and 8 Serratia marcescens strains . Penicillin in combination with EGCg at 12.5 microg mL(-1) showed the most potent synergy against 100% penicillinase-producing S . aureus . However, cefotaxime or imipenem in combination with higher concentration of EGCg (100 microg mL(-1)) only showed slight synergy against 2 of 17 Gram-negative rods . Similar to the effect on the penicillinase from S . aureus, however, EGCg also directly inhibited the extracted beta-lactamases from the Gram-negative rods, thereby protecting beta-lactams from inactivation . The different effects of the combinations on different beta-lactamase-producing species were confirmed to be related to the cellular locations of beta-lactamases . In contrast to a 32.7% extracellular fraction of total beta-lactamase activity in a penicillinase-producing S . aureus, the fractions were 0.6%, 0.6% and 1.2% in a TEM-derived extended-spectrum beta-lactamase-producing E . coli, an inhibitor-resistant beta-lactamase-producing K . pneumoniae and an IMP-producing S . marcescens, respectively . In conclusion, the combination of penicillin with EGCg showed potent synergy against penicillinase-producing S . aureus in-vitro . The combinations of beta-lactams and EGCg against beta-lactamase-producing Gram-negative rods do indicate a limitation owing to the cellular location of beta-lactamases.

Appl Environ Microbiol, 2003 Jul, 69(7), 3901 - 10
Identification and characterization of a GDSL esterase gene located proximal to the swr quorum-sensing system of Serratia liquefaciens MG1; Riedel K et al.; Serratia liquefaciens MG1 employs the swr quorum-sensing system to control various functions, including production of extracellular enzymes and swarming motility . Here we report the sequencing of the swr flanking DNA regions . We identified a gene upstream of swrR and transcribed in the same direction, designated estA, which encodes an esterase that belongs to family II of lipolytic enzymes . EstA was heterologously expressed in Escherichia coli, and the substrate specificity of the enzyme was determined in crude extracts . With the aid of zymograms visualizing EstA on polyacrylamide gels and by the analysis of a transcriptional fusion of the estA promoter to the promoterless luxAB genes, we showed that expression of the esterase is not regulated by the swr quorum-sensing system . An estA mutant was generated and was found to exhibit growth defects on minimal medium containing Tween 20 or Tween 80 as the sole carbon source . Moreover, we show that the mutant produces greatly reduced amounts of N-acyl-homoserine lactone (AHL) signal molecules on Tween-containing medium compared with the wild type, suggesting that under certain growth conditions EstA may be important for providing the cell with precursors required for AHL biosynthesis.

J Antimicrob Chemother, 2003 Aug, 52(2), 176 - 9 Epub 2003 Jul 01.
An RND-type multidrug efflux pump SdeXY from Serratia marcescens; Chen J et al.; OBJECTIVES: Serratia marcescens, an important cause of nosocomial infections, shows intrinsic resistance to a wide variety of antimicrobial agents (multidrug resistance) . Multidrug efflux pumps are often involved in the multidrug resistance in many bacteria . A study was undertaken to characterize the multidrug efflux pumps in S . marcescens . METHODS: The genes responsible for the multidrug resistance phenotype in S . marcescens were cloned into Escherichia coli KAM32, a drug-hypersusceptible strain, for further analysis . RESULTS: We cloned sdeXY genes and determined the nucleotide sequence . Clones that carried the sdeXY genes displayed reduced susceptibility to several antimicrobial agents including erythromycin, tetracycline, norfloxacin, benzalkonium chloride, ethidium bromide, acriflavine and rhodamine 6G . A protein similarity search using GenBank revealed that SdeY is a member of the resistance nodulation cell-division (RND) family of multidrug efflux proteins and SdeX is a member of the membrane fusion proteins . Introduction of sdeXY into E . coli cells possessing tolC, but not in cells lacking tolC, resulted in multidrug resistance . We observed energy-dependent ethidium efflux in cells of E . coli KAM32 possessing sdeXY and tolC . CONCLUSIONS: SdeXY is the first RND-type multidrug efflux pump to be characterized in multidrug-resistant S . marcescens.

J Biol Chem, 2003 Oct 3, 278(40), 38247 - 53 Epub 2003 Jun 26.
Antifolding activity of the SecB chaperone is essential for secretion of HasA, a quickly folding ABC pathway substrate; Wolff N et al.; We have previously shown that SecB, the ATP-independent chaperone of the Sec pathway, is required for the secretion of the HasA hemophore from Serratia marcescens via its type I secretion pathway, both in the reconstituted system in Escherichia coli and in the original host . The refolding of apo-HasA after denaturation with guanidine HCl was followed by stopped-flow measurements of fluorescence of its single tryptophan, both in the absence and presence of SecB . In the absence of SecB, HasA folds very quickly with one main phase (45 s(-1)) accounting for 92% of the signal . SecB considerably slows down HasA folding . At stoichiometric amounts of SecB and HasA, a single phase (0.014 s(-1)) of refolding is observed . Two double point mutants of HasA were made, abolishing two hydrogen bonds between N-terminal and C-terminal side chain residues . In both cases, the mutants essentially maintained the same secondary and tertiary structure as wild-type HasA and were fully functional . Refolding of both mutants was much slower than that of wild-type HasA and they were secreted essentially independently of SecB . We conclude that SecB has mainly an antifolding function in the HasA ABC secretion pathway.

Am J Gastroenterol, 2003 May, 98(5), 1022 - 7
Endoscopic ultrasound-guided biopsy for the diagnosis of focal lesions of the spleen; Fritscher-Ravens A et al.; OBJECTIVES: Needle biopsy of splenic lesions using computed tomography (CT) or ultrasound (US) is difficult if the size of the lesion is small . It may be dangerous if the lesion is adjacent to the splenic hilum or located peripherally . We used endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) to elucidate the tissue diagnosis of splenic abnormalities . METHODS: EUS-FNA was performed in 12 patients when US- or CT-guided biopsy was inconclusive (n = 5), was not attempted because of small tumor size (0.9-1.4 cm; N = 4), or was considered dangerous (n = 3) . A linear echo-endoscope and 22-gauge needles were used for cytology and bacteriology . RESULTS: The age of the patients was 19-68 yr (median 32 yr) . Seven patients were male and five female . The size of the lesions was 0.8-4.2 cm (median 1.4 cm) . Cytology was inadequate in one patient . Bacteriology was positive for Staphylococcus aureus and Serratia in one patient each, and cultures were positive for Mycobacterium tuberculosis in two patients . A positive diagnosis was made in 10 of 12 patients (83%) . Final diagnoses were tuberculosis in two patients, Hodgkin's disease in two, sarcoidosis in two, abscesses in two, metastatic colon cancer in one, and infarction in one . Suspected recurrence of non-Hodgkin's lymphoma was not confirmed in one case . One patient experienced pain after puncture, but no hematoma was demonstrated on subsequent US examination . CONCLUSIONS: EUS-FNA cytodiagnosis in patients with unknown splenic lesions seems feasible, even in very small foci, when CT- or US-guided biopsy fails . Additional material for bacteriology may show benign treatable diseases such as abscesses or tuberculosis.

J Appl Microbiol, 2003, 95(1), 186 - 95
Characterization of Serratia marcescens surviving in disinfecting footbaths; Langsrud S et al.; AIM: To determine if disinfecting footbaths in the food industry were contaminated with bacteria and to characterize some of the bacteria present . METHODS AND RESULTS: Bacterial strains were isolated from disinfecting footbaths containing TEGO 103G (amphoteric disinfectant) or TP-99 (alkyl amino acetate-based disinfectant) in five of six dairy factories . Fourteen strains identified as Cedecea spp . by their fatty acid composition were further characterized . Results from Rapid ID 32 E API analysis and 16S-rDNA-sequencing showed that all strains were Serratia marcescens . Unlike S . marcescens ATCC 13880, the isolates from disinfecting footbaths were not killed (<5 log10 reduction) by the recommended in-use concentration of TEGO 103G, TEGO 51 or benzalkonium chloride . Survival and multiplication in tap water with an in-use concentration of TEGO 103G was demonstrated for one of the strains . All strains were killed by the in-use concentrations of commercial disinfectants based on peracetic acid, hypochlorite, quaternary ammonium compounds and alkyl amino acetate (TP-99) . There were no indications of cross-resistance between disinfectants and antibiotics . CONCLUSION: Serratia marcescens may survive and multiply in disinfecting footbaths containing TEGO 103G or alkyl amino acetate because of disinfectant resistance . SIGNIFICANCE AND IMPACT OF THE STUDY: Disinfecting footbaths may act as contamination sources in food factories and should not be used without regular hygienic monitoring.

FEMS Microbiol Lett, 2003 Jun 6, 223(1), 41 - 6
Membrane filter (pore size, 0.22-0.45 micro m; thickness, 150 micro m) passing-through activity of Pseudomonas aeruginosa and other bacterial species with indigenous infiltration ability; Hasegawa H et al.; Bacteria growing on MF-Millipore filters (thickness, 150 micro m) passed through the underlying membrane by their infiltration activity . Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli passed through a 0.45- micro m pore size filter within 48-96 h . Pseudomonas aeruginosa, Serratia marcescens, and Listeria monocytogenes passed through a 0.3- micro m pore size filter . P . aeruginosa passed through a 0.22- micro m pore size filter . The membranes which allowed passing-through of bacteria showed normal bubble point values in the integrity test . Studies with isogenic S . marcescens mutants indicated that flagellum-dependent motility or surface-active exolipid were important in the passing-through . P . aeruginosa PAO1 C strain defective in twitching motility was unable to pass through the 0.22- micro m filter . Scanning electron microscopy showed bacteria passing-through the 0.22- micro m filter . Millipore membrane filters having well-defined reticulate structures will be useful in the study of infiltration activity of microbes.

Mol Microbiol, 2003 Jun, 48(6), 1467 - 80
Haemophore-mediated signal transduction across the bacterial cell envelope in Serratia marcescens: the inducer and the transported substrate are different molecules; Rossi MS et al.; Numerous bacteria are able to use free and haemoprotein-bound haem as iron sources because of the action of small secreted proteins called haemophores . Haemophores have very high affinity for haem, and can therefore extract haem from the haem-carrier proteins and deliver it to the cells by means of specific cell surface receptors . Haem is then taken up and the empty haemophores are recycled . Here, we report a study of the regulation of the Serratia marcescens has operon which is involved in haemophore-dependent haem acquisition . We characterized two genes encoding proteins homologous to specific ECF sigma and antisigma factors . We showed that they regulate the synthesis of the haemophore-specific outer membrane receptor, HasR, by a signal transduction mechanism similar to the siderophore surface-signalling systems . We also showed the essential role of HasR itself in this process . Using haem-loaded and haem-free haemophore, we identified the stimulus for the HasR-mediated signal transduction as being the binding of the haem-loaded haemophore to HasR . Thus, unlike siderophore-uptake systems, in which the signalling molecule is the transported substrate itself, in the haemophore-dependent haem uptake system the inducer and the transported substrate are different compounds.

Arch Soc Esp Oftalmol, 2003 May, 78(5), 281 - 3
{Endogenous serratia marcescens endophthalmitis diagnosis with PCR}; Asensio Sanchez VM et al.; PURPOSE/METHOD: We report the case of a 75-year-old man with endogenous endophthalmitis in the left eye . Culture results were negative . PCR for several Gram-negative bacterias genome was performed . RESULTS/CONCLUSIONS: Polymerase chain reaction showed amplification of Serratia marcescens genome . Our case indicates that PCR can be a valuable tool in the diagnosis of culture negative endophthalmitis.

J Insect Physiol, 1999 Jan, 45(1), 75 - 83
Eicosanoids mediate nodulation reactions to bacterial infections in adults of the cricket, Gryllus assimilis; Miller JS et al.; Nodulation is the temporally and quantitatively most important cellular defense reaction to bacterial infections in insects . Inhibition of eicosanoid biosynthesis in adults of the cricket, Gryllus assimilis, immediately prior to intrahemocoelic injections of the bacterium, Serratia marcescens, sharply reduced the nodulation response . Separate treatments with specific inhibitors of phospholipase A(2), cyclooxygenase, and lipoxygenase reduced nodulation, supporting our view that nodule formation is a complex process involving lipoxygenase and cyclooxygenase products . The inhibitory influence of dexamethasone was apparent within 2h of injection, and nodulation was significantly reduced, relative to control crickets, over 22h . The dexamethasone effects were reversed by treating bacteria-injected insects with the eicosanoid-precursor polyunsaturated fatty acid, arachidonic acid . Low levels of arachidonic acid were detected in fat body phospholipids, and fat body preparations were shown to be competent to biosynthesize eicosanoids from exogenous radioactive arachidonic acid . These findings in a hemimetabolous insect broaden our hypothesis that eicosanoids mediate cellular immune reactions to bacterial infections in most, if not all, insects.

J Insect Physiol, 1999 Oct, 45(10), 923 - 931
Eicosanoids mediate nodulation reactions to bacterial infections in adults of two 17-year periodical cicadas, Magicicada septendecim and M . cassini; Tunaz H et al.; Nodulation is the first and quantitatively most important cellular defense reaction to bacterial infections in insects . Treating adults of the 17-year periodical cicadas, Magicicada septendecim and M . cassini, with eicosanoid biosynthesis inhibitors immediately prior to intrahemocoelic injections of the bacterium, Serratia marcescens, sharply reduced the nodulation response to bacterial challenges . Separate treatments with specific inhibitors of phospholipase A(2), cyclooxygenase, and lipoxygenase reduced nodulation, supporting our view that nodule formation is a multi-step process in which individual steps are separately mediated by lipoxygenase and cyclooxygenase products . The inhibitory influence of dexamethasone was apparent by 2 h after injection, and nodulation was significantly reduced, relative to control insects, over the following 14 h . The dexamethasone effects were reversed by treating bacteria-challenged insects with the eicosanoid-precursor polyunsaturated fatty acid, arachidonic acid . Low levels of arachidonic acid were detected in fat body phospholipids . These findings in adults of an exopterygote insect species with an unusual life history pattern broaden our hypothesis that eicosanoids mediate cellular immune reactions to bacterial infections in most, if not all, insects.

J Insect Physiol, 2001 Dec, 47(12), 1409 - 1417
Eicosanoids mediate microaggregation reactions to bacterial challenge in isolated insect hemocyte preparations; Miller JS et al.; Nodule formation is the quantitatively predominant insect cellular defense reaction to bacterial challenges, responsible for clearing the largest proportion of infecting bacteria from circulation . It has been suggested that eicosanoids mediate several steps in the nodulation process, including formation of hemocyte microaggregates, an early step in the process . While fat body and hemocytes are competent to biosynthesize eicosanoids, the source of the nodulation-mediating eicosanoids remains unclear . To investigate this issue, we studied hemocyte microaggregation reactions to bacterial challenge in vitro . Hemocyte suspensions from the tobacco hornworm, Manduca sexta, were treated with the phospholipase A(2) inhibitor, dexamethasone, then challenged with the bacterium Serratia marcescens . Preparations treated with dexamethasone yielded fewer hemocyte microaggregations than untreated, control preparations . Furthermore, the influence of dexamethasone was reversed by amending experimental (dexamethasone-treated) preparations with the eicosanoid biosynthesis precursor, arachidonic acid . Palmitic acid, which is not a substrate for eicosanoid biosynthesis, did not reverse the influence of dexamethasone on the microaggregation reaction . The influence of dexamethasone was also reversed by adding filtered media from challenged hemocyte preparations to dexamethasone-treated preparations . Finally, most hemocyte preparations treated with selected eicosanoid biosynthesis inhibitors formed fewer hemocyte microaggregations than control preparations . The 5- and 12-lipoxygenase inhibitor, esculetin, did not influence the formation of hemocyte microaggregations in this system . These results are consistent with similar investigations performed in vivo, and we infer that hemocytes are responsible for forming and secreting eicosanoids, which subsequently initiate nodulation by mediating hemocyte microaggregation.

J Insect Physiol, 1997 Feb 21, 43(2), 125 - 133
Eicosanoids mediate microaggregation and nodulation responses to bacterial infections in black cutworms, Agrotis ipsilon, and true armyworms, Pseudaletia unipuncta; Stanley-Samuelson D et al.; Nodulation is the first, and quantitatively predominant, cellular defense reaction to bacterial infection in insects and other invertebrates . Inhibition of eicosanoid biosynthesis in true armyworms, Pseudaletia unipuncta, and black cutworms, Agrotis ipsilon, immediately prior to intrahemocoelic injections with heat-killed preparations of the bacterium, Serratia marcescens, severely impaired the nodulation response . Five eicosanoid biosynthesis inhibitors, including dexamethasone (a phospholipase A(2) inhibitor), indomethacin, ibuprofen (cyclooxygenase inhibitors), phenidone (dual lipoxygenase/cyclooxygenase inhibitor) and eicosatetraynoic acid (an arachidonic acid analog that inhibits all arachidonic acid metabolism) severely reduced nodulation in infected insects . The dexamethasone effects were reversed by treating true armyworms with arachidonic acid immediately after infection . In addition to these pharmacological findings, we demonstrate that an eicosanoid biosynthesis system is present in these insects . Arachidonic acid is present in fat body phospholipids at about 0.4% of total phospholipid fatty acids . Fat body expressed a phospholipase A(2) that can hydrolyze arachidonic acid from the sn-2 position of cellular phospholipids . Fat body preparations were competent to biosynthesize prostaglandins, of which PGE(2) was the major product . These findings support the hypothesis that eicosanoids mediate cellular immune reactions in insects.

J Biochem (Tokyo), 2003 Feb, 133(2), 253 - 8
Kinetic studies on the hydrolysis of N-acetylated and N-deacetylated derivatives of 4-methylumbelliferyl chitobioside by the family 18 chitinases ChiA and ChiB from Serratia marcescens; Honda Y et al.; Kinetic analyses of the hydrolysis reactions of N-acetylated and N-deacetylated derivatives of 4-methylumbelliferyl chitobioside {(GlcNAc)(2)-UMB (1), GlcN-GlcNAc-UMB (2), GlcNAc-GlcN-UMB (3), and (GlcN)(2)-UMB (4)} by ChiA and ChiB from Serratia marcescens were performed . Both enzymes released UMB from all compounds apart from 4 . The S-v curves of the hydrolyses of 1 by ChiA and ChiB both exhibited atypical kinetic patterns, and the shapes of the two S-v curves were different from one another . However, both curve shapes were explained by assuming some of the enzyme present formed complexes with multiple molecules of the substrate . Conversely, the S-v curves generated in the cleavage of 2 and 3 by ChiA exhibited typical Michaelis-Menten profiles . Both enzymes hydrolysed 2 with an approximately 14-fold higher K(m) value relative to 1, indicating that the N-acetyl group was recognised at the -2 subsite . The k(cat) value obtained with ChiA was identical to the k(cat) value observed for 1 . However, the k(cat) value for ChiB was one-fourth that of 1, suggesting that the removal of the N-acetyl group caused an increase in the formation of a non-productive ES-complex . ChiA and ChiB hydrolysed 3 with 5- and 20-fold greater K(m) values relative to 1, respectively, and 60- and 30-fold smaller k(cat) values relative to 1, respectively . The reaction mechanism of family 18 chitinases is discussed based upon the results obtained from the hydrolysis of these compounds.

Biol Pharm Bull, 2003 May, 26(5), 589 - 94
Dependence of hydrolysis of beta-lactams with a zinc(II)-beta-lactamase produced from Serratia marcescens (IMP-1) on pH and concentration of zinc(II) ion: dissociation of Zn(II) from IMP-1 in acidic medium; Goto M et al.; The pH dependence for the hydrolysis of beta-lactam antibiotics by a metallo-beta-lactamase (IMP-1) produced from Serratia marcescens was investigated varying the concentration of Zn(II) . The activity of IMP-1 for imipenem was decreased at pH less than pH 5.3 without external addition of Zn(II) ions but was recovered with addition of Zn(II) . Varying the concentration of external Zn(II), the molar activity of the enzyme, k(obs), that was defined by the velocity of hydrolysis of imipenem/concentration of IMP-1 was expressed by k(obs)=v(init)/{E}(T)=k(max){Zn}/(K(d)+{Zn}) in which K(d) stands for the dissociation constant between Zn(II) and IMP-1 . The dissociation constants, K(d), vary with pH; K(d)=840 x 10(-6) M at pH 4.3 and K(d)=0.19 x 10(-6) M at pH 6.0 . The plot of -log K(d) against pH showed a straight line having a slope of 4.0 below pH 5.0, showing the existence of four functional groups which may be protonated upon dissociation of Zn(II) ion(s) . The k(cat), K(m), and k(cat)/K(m) of hydrolysis of imipenem and cephalothin in the presence of sufficient concentration of Zn(NO(3))(2) for saturation of IMP-1 with Zn(II) showed similar dependency to each other on pH between pH 6.0 and 9.0.

J Clin Microbiol, 2003 May, 41(5), 2233 - 4
Infection with an extended-spectrum beta-lactamase-producing strain of Serratia marcescens following tongue reconstruction; Dhawan B et al.; We report a case of postsurgical wound infection of polymicrobial etiology caused by Serratia marcescens and Pseudomonas aeruginosa following the use of a radial forearm free flap for oncological tongue reconstruction . S . marcescens was a producer of SHV-12 extended-spectrum beta-lactamase (ESBL) . This is the first report from India of this ESBL . S . marcescens and P . aeruginosa were resistant to the empirical perioperative antibiotics administered . Delay in the recognition of the type of infection and in the institution of appropriate therapy resulted in total loss of the free flap.

J Microbiol Methods, 2003 Jul, 54(1), 131 - 5
A rapid and specific method to screen environmental microorganisms for cephalosporin acylase activity; Zhu S et al.; Medically useful semisynthetic cephalosporin antibiotics are made from precursor 7-aminocephalosporanic acid (7-ACA) . Cephalosporin acylase (CA), which catalyzes hydrolysis of both glutaryl-7-aminocephalosporanic acid (GL-7ACA) and cephalosporin C (CPC) to 7-ACA, is thus a very important enzyme for producing semisynthetic beta-lactam antibiotics . To facilitate the attempts of obtaining the microorganisms with higher CA activity from natural environments, a new and specific method for screening environmental microorganisms with cephalosporin acylase activity was developed . The core part of cephalosporin was replaced by 6-amino penicillinic acid (6-APA) to generate new substrates glutaryl-6-APA and adipoyl-6-APA for screening . Serratia marcescens that is sensitive to 6-APA and resistant to penicillin G, glutaryl-6-APA and adipoyl-6-APA was used as an indicator strain in an overlaid-agar screening system . A strain capable of producing cephalosporin acylase was selected from thousands of candidates by this method . Because of its specificity, simplicity and sensitivity, the method could be easily installed into a high-throughout system.

Diagn Microbiol Infect Dis, 2003 Apr, 45(4), 221 - 4
Confirmation of extended-spectrum beta-lactamase-producing Serratia marcescens: preliminary report from Taiwan; Yu WL et al.; Although Serratia marcescens is a common cause of nosocomial infection in Taiwan, strains producing extended-spectrum beta-lactamases (ESBLs) are rare . We detected four clinical isolates of S . marcescens from Taiwan that exhibited resistance to cefotaxime (MICs, > 256 microg/ml) and cefepime (MICs, > or = 32 microg/ml), but were susceptible to imipenem and meropenem . Transconjugants revealed similar MIC profiles when compared to the parental strains . Isoelectric focusing revealed one major transferable beta-lactamase (pI 8.4), which was further identified as CTX-M-3 by polymerase chain reaction and gene sequencing . An AmpC-like enzyme (pI 8.8) was not transferable . All four isolates had significant MIC reductions of > or =3 log(2) dilutions for cefepime in the presence of clavulanic acid, compatible with the presence of an ESBL (CTX-M-3) . Clavulanate did not significantly reduce the cefotaxime MIC for one isolate that may co-produce high-level AmpC beta-lactamase (pI 8.8) . Since high-level AmpC expression has minimal effect on the activity of cefepime, isolates co-producing AmpC beta-lactamase may be recognized as additional ESBL producers by using cefepime as an ESBL screening agent.

Biosci Biotechnol Biochem, 2003 Mar, 67(3), 499 - 507
Regioselective glucosylation of pyridoxine by microorganisms; Asano Y et al.; Microorganisms from culture collections and isolates from nature were screened for the ability to catalyze the regioselective glucosylation of pyridoxine (PN) to produce pyridoxine 5'-alpha-D-glucoside (PN-5'-alpha-G) or pyridoxine 4'-alpha-D-glucoside (PN-4'-alpha-G) . Transglucosylation activity specific to 5'-position of PN was found in fungi belonging to genera such as Coriolus and Verticillium, and activity at the 4'-position of PN was found in bacteria belonging to genera such as Bacillus and Serratia . From 100 mM PN, intact cells of Verticillium dahliae TPU 4900 produced 42 mM (13.9 mg/mL) PN-5'-alpha-G after 70 h of reaction . Intact cells of Bacillus cereus TPU 5504 produced 33 mM (10.9 mg/mL) PN-4'-alpha-G after 19 h of reaction . The selectivities for 5'- and 4'-positions were 80% and 90%, respectively.

Parassitologia, 2002 Dec, 44(3-4), 149 - 51
Aerobic and microaerophilic bacteria isolated from Psoroptes cuniculi; Perrucci S et al.; The bacterial flora of Psoroptes cuniculi removed from nine naturally infested rabbits was investigated . Mites were collected in sterile glass tubes; half of the mites were surface sterilised, the others were not . All mites were crushed using sterile glass pestles, placed in Buffered Peptone Broth, smeared on to several culture media, by glass rods, and incubated at 37 degrees C for 48 hours, aerobically and/or in 5% CO2 . Representative colonies were removed and streaked on to several selective media . Different colour changes of the selective media used, macro and microscopic morphology, ability to grow aerobically, Gram staining, and several biochemical tests evaluated with API test strips, were used for bacterial identification . Staphylococcus aureus, Serratia marcescens and S . odorifera were the bacteria isolated from surface sterilised mites.

J Antimicrob Chemother, 2003 May, 51(5), 1153 - 8 Epub 2003 Apr 14.
Aspects of the antimicrobial mechanisms of action of a polyquaternium and an amidoamine; Codling CE et al.; OBJECTIVES: Polyquad (Alcon) (polyquaternium-1, PQ-1) and Aldox (Alcon) (myristamidopropyl dimethylamine, MAPD) are two biocides that are used commercially in a contact lens disinfecting solution, namely Opti-Free Express (Alcon) multi-purpose disinfecting solution . Their potential mechanisms of action were investigated against a range of common ocular pathogens . These were Acanthamoeba castellanii (trophozoites and cysts), Aspergillus fumigatus, Candida albicans, Pseudomonas aeruginosa, Serratia marcescens and Staphylococcus aureus . METHODS: Three aspects were investigated: the lethal effects of the biocides on the organisms, the leakage of K+ from treated cells, and the lysis of spheroplasts derived from the cells . RESULTS: PQ-1 was found to have predominantly antibacterial activity, and induced K+ leakage from the bacteria and C . albicans . It also caused lysis of spheroplasts of S . marcescens, but not those of C . albicans . MAPD was active against all of the organisms, but showed higher activity against the fungi and amoeba . It induced K+ leakage from A . fumigatus and C . albicans, and like PQ-1, lysed the spheroplasts of S . marcescens but not C . albicans . CONCLUSIONS: The two biocides have different spectra of antimicrobial activity . PQ-1 has mainly antibacterial activity, whereas MAPD was active against all of the test organisms, particularly the fungi.

Biometals, 2003 Sep, 16(3), 447 - 53
Action of hexaamminecobalt on the activity of Serratia marcescens nuclease; Filimonova M et al.; Using CD spectroscopic and kinetic analysis, a refined mechanism of Co(NH3)6(3+) action on activity of Serratia marcescens nuclease was elucidated . The mechanism was identical with previously found mechanisms of Mg2+ and C7H5O2Hg+ . Similarly to Mg2+ and C7H5O2Hg+, Co(NH3)6(3+) binding to the DNA substrate induced changes in the secondary structure which resulted in changes of the enzymatic activity of the S . marcescens nuclease . Upon binding of 0.03 Co(NH3)6(3+) per DNA phosphate, highly polymerized DNA displayed A-form characteristics . The DNA transition from B-form to A-form intermediate was followed by a decrease of the nuclease activity . The diminishing nuclease activity was consistent with diminishing values of Km and Kcat . Co(NH3)6(3+) binding to the highly polymerized DNA caused a 1.7-2.8-fold decrease in Km, and 13.3-19.9 decrease in Vmax compared with Mg-DNA complex . A vast excess of Co(NH3)6(3+) did not affect the activity of S . marcescens nuclease if the DNA in the assay mixture remained in its B-form conformation . Preincubation of S . marcescens nuclease with Co(NH3)6(3+) did not influence the tertiary structure of the enzyme.

Infect Control Hosp Epidemiol, 2003 Mar, 24(3), 195 - 7
Pseudo-outbreak of Pseudomonas aeruginosa and Serratia marcescens related to bronchoscopes; Silva CV et al.; OBJECTIVE: To investigate an apparent outbreak involving simultaneous isolation of Pseudomonas aeruginosa and Serratia marcescens from bronchoalveolar lavage (BAL) samples . DESIGN: Retrospective and prospective cohort studies using chart review, environmental sampling, and ribotyping of all available isolates . Cleaning and disinfection procedures for the bronchoscopes were also evaluated . SETTING: A 380-bed private hospital in Sao Paulo, Brazil PATIENTS: Forty-one patients who underwent bronchoscopic procedures between December 1994 and October 1996 and from whom P . aeruginosa and S . marcescens were concomitantly isolated . Bronchoscopes and related items were microbiologically assessed . RESULTS: P . aeruginosa and S . marcescens were simultaneously isolated from BAL samples 12.6% of the time (41 of 324) during the epidemic period versus 1.8% of the time (1 of 54) in the pre-epidemic period (P = .035) . Ribotyping revealed two strains of P . aeruginosa and one of S . marcescens that were isolated from BAL samples of patients with no signs of respiratory tract infection, suggesting a pseudo-outbreak . Evaluation of bronchoscope disinfection revealed that inappropriate methods were being used . Implementation of simple control measures resulted in a significant decrease in simultaneous isolation of these species . CONCLUSION: Prevention of pseudo-outbreaks requires meticulous use of preventive measures for infection-prone medical procedures.

Curr Med Chem Anti-Canc Agents, 2001 Aug, 1(2), 195 - 218
Synthesis, proton-affinity and anti-cancer properties of the prodigiosin-group natural products; Manderville RA; The prodigiosin-group natural products are a family of tripyrrole red-pigments that are produced by microorganisms such as Streptomyces and Serratia and contain a common 4-methoxy-2,2'-bipyrrole ring system . They were first isolated in 1929 and studied as antibiotic and cytotoxic agents in the 1960s, but were not developed clinically due to their high systemic toxicity . However, during the past decade some prodigiosins have shown potentially useful immunosuppressive activity when administered at doses that are not toxic . They have also been found to exhibit selective cytotoxicity against melanoma and liver cancer cells . These results have fueled various studies on the biological mechanisms of the prodigiosins and it has now been established that they inhibit phosphorylation and activation of JAK-3, a cytoplasmic tyrosine kinase associated with the cell surface receptor component called common gamma-chain . They also uncouple lysosomal vacuolar-type ATPases through promotion of H(+)/Cl(-) symport and facilitate oxidative double-strand DNA cleavage in the presence of copper . A simple and elegant synthesis of the prodigiosins has also been developed, which has allowed a number of the natural prodigiosins and synthetic analogues to be prepared . These studies have served to renew interest in the prodigiosin-group natural products . In this review the recent advances on the synthesis, proton-affinity and biological activities of the prodigiosins are discussed . With regard to their anti-cancer properties, particular attention is given to their ability to facilitate oxidative DNA damage, which provides a rationale for the cytotoxic properties of the prodigiosin-group natural products.

J UOEH, 2003 Mar 1, 25(1), 89 - 101
{Control measures against Serratia marcescens colonization at the neonatal intensive care unit of UOEH hospital}; Ikeno T et al.; In September 2001, twelve neonatal intensive care unit (NICU) patients were found to be colonized with pigment-producing strains of Serratia marcescens . The UOEH Infection Control Group (ICG) committee investigated the source of this epidemic and carried out several remedial measures . Immediate investigation of both the environment and the hands of health care workers were enforced . The most likely means of transmission was thought to be from the hands contaminated with S . marcescens that was found on antiseptic cotton, kept in shared stainless steel canisters, used for wiping the patients' buttocks . Therefore, we suggested the following interventions: 1) abolish the stainless steel canisters, and prepare antiseptic cottons for each patient, 2) monitor cultures with some specimens for all patients in the NICU, 3) periodically investigate the environment, 4) enforce workers to wash and disinfect their hands before and after patient care, 5) use new gloves for each treatment, 6) re-examine and modify the caring procedures for inpatients by the nursing staff . In January 2002, this nosocomial colonization came to an end without any serious infection . One of the key points of this success was the quick response by the clinical staff and ICG committee members to the laboratory results of bacteriological examinations . Furthermore, the early investigation of reservoir and good communication between the clinical staff and ICG committee members mostly prevented this nosocomial colonization from becoming worse.

EMBO J, 2003 Apr 1, 22(7), 1451 - 60
Virulence factors of the human opportunistic pathogen Serratia marcescens identified by in vivo screening; Kurz CL et al.; The human opportunistic pathogen Serratia marcescens is a bacterium with a broad host range, and represents a growing problem for public health . Serratia marcescens kills Caenorhabditis elegans after colonizing the nematode's intestine . We used C.elegans to screen a bank of transposon-induced S.marcescens mutants and isolated 23 clones with an attenuated virulence . Nine of the selected bacterial clones also showed a reduced virulence in an insect model of infection . Of these, three exhibited a reduced cytotoxicity in vitro, and among them one was also markedly attenuated in its virulence in a murine lung infection model . For 21 of the 23 mutants, the transposon insertion site was identified . This revealed that among the genes necessary for full in vivo virulence are those that function in lipopolysaccharide (LPS) biosynthesis, iron uptake and hemolysin production . Using this system we also identified novel conserved virulence factors required for Pseudomonas aeruginosa pathogenicity . This study extends the utility of C.elegans as an in vivo model for the study of bacterial virulence and advances the molecular understanding of S.marcescens pathogenicity.

Microb Ecol, 2003 Mar, 45(3), 226 - 36 Epub 2003 Mar 28.
Presence of N-acyl homoserine lactones in soil detected by a whole-cell biosensor and flow cytometry; Burmolle M et al.; Quorum sensing enables bacteria to regulate expression of certain genes according to population density . N-acyl homoserine lactone (AHL)-based quorum sensing is known to be widespread among gram-negative bacteria . Several bacterial whole-cell biosensors for AHL detection have been developed and some were used in in situ studies of AHL production . From these studies our knowledge of the significance of quorum sensing in various environments has been improved . However, very little is known about production of AHLs in soil environments . In the present study, an approach for detecting AHL production in bulk soil was developed . A whole-cell biosensor based on the regulatory region of the lux-operon from Vibrio fischeri fused to gfp was constructed, resulting in a luxR-PluxI-gfpmut3*-fusion in the high copy plasmid, pAHL-GFP . Escherichia coli MC4100 harboring pAHL-GFP responded to the AHL-compound N-octanoyl homoserine lactone (OHL) by expressing green fluorescence . In situ application of E . coli MC4100/pAHL-GFP was tested by adding OHL in different concentrations to sterile soil microcosms . E . coli MC4100/pAHL-GFP were incubated in the soil microcosms and extracted by an improved Nycodenz-extraction method optimized for flow cytometry . The presence of induced cells was then verified by single-cell analysis by flow cytometry . OHL concentrations between 0.5 and 50 nmol per g soil were detected . When introducing the AHL-producing Serratia liquefaciens to soil microcosms, expression of green fluorescent protein was induced in E . coli MC4100/pAHL-GFP . Thereby, the ability of this strain to detect excretion of AHLs by S . liquefaciens in sterile soil was shown . The use of an improved extraction method and a whole-cell biosensor combined with flow cytometry analysis proved to be promising tools in future studies of AHL production by microbial populations in soil environments.

Arch Insect Biochem Physiol, 2003 Apr, 52(4), 183 - 92
Eicosanoid involvement in the regulation of behavioral fever in the desert locust, Schistocerca gregaria; Bundey S et al.; The desert locust Schistocerca gregaria behaviorally thermoregulates in order to try and maintain a favoured "set point" body temperature . Locusts infected with the deuteromycete fungal pathogen Metarhizium anisopliae var acridumchoose a significantly elevated temperature . This "behavioral fever" greatly delays the progress of mycosis . We have confirmed this phenomenon and shown that desert locusts also fever when infected with the bacterial pathogen Serratia marcescens . Elevation in the prefered environmental temperature occurs also upon injection with laminarin and lipopolysaccharide (microbial cell wall components) . Since such treatments also stimulate the immune system it would appear that "behavioral fever" is probably a feature of the immune response . The eicosanoid biosynthesis inhibitor dexamethasone prevented laminarin invoked fever . This effect was reversable by arachidonic acid . Therefore in common with the febrile response in mammals behavioral fever in insects may be mediated locally by circulating eicosanoids .

J Chromatogr B Analyt Technol Biomed Life Sci, 2003 Mar 25, 786(1-2), 33 - 7
Two-step purification of the outer membrane transporter and activator protein ShlB from Escherichia coli using internally His6-tagged constructs; Sauter SR et al.; ShlB from Serratia marcescens was isolated and purified from a porin-deficient Escherichia coli BL21 strain using a combination of detergent extraction, affinity and ion-exchange chromatography . An internal histidine affinity tag was introduced that did not interfere with activity . At each stage of the purification scheme biological activity of the ShlB protein was assessed . Using this scheme, several His(6)-tagged mutants of ShlB were purified to electrophoretic homogeneity.

Histol Histopathol, 2003 Apr, 18(2), 379 - 85
Effects of the proapoptotic drug prodigiosin on cell cycle-related proteins in Jurkat T cells; Perez-Tomas R et al.; Prodigiosin (PG) is a red pigment produced by Serratia marcescens with immunosuppressive and apoptotic activities . In this study, we sought to examine the effect of PG on cell cycle-related proteins . The antiproliferative activity of PG was tested using human Jurkat leukaemia T cells in culture . PG-inhibited cell proliferation was determined using thymidine incorporation assay . PG-arrested cell cycle was analysed using immunoblot analysis with specific antibodies against cell cycle-related proteins and kinase assays of cdk2 . Apoptosis was determined by Hoechst staining and analysis of DNA fragmentation . PG inhibited cyclin E, cdk2, p27 and p21, the induction of the cyclin A-cdk2 and cyclin E-cdk2 kinase activity, and the phosphorylation of Rb in leukaemic Jurkat cells . We confirmed that PG induces apoptosis by the characteristic DNA laddering pattern and condensed nuclei or apoptotic bodies identified by fluorescence microscopy . These results indicate that PG and other family members form a new group of molecules with a common mechanism of action and specific molecular targets, raising the possibility of their therapeutic use as antineoplastic drugs.

Braz J Med Biol Res, 2003 Mar, 36(3), 351 - 9 Epub 2003 Mar 07.
Biological activity of Serratia marcescens cytotoxin; Carbonell GV et al.; Serratia marcescens cytotoxin was purified to homogeneity by ion-exchange chromatography on a DEAE Sepharose Fast Flow column, followed by gel filtration chromatography on a Sephadex G100 column . The molecular mass of the cytotoxin was estimated to be about 50 kDa . Some biological properties of the cytotoxin were analyzed and compared with well-characterized toxins, such as VT1, VT2 and CNF from Escherichia coli and hemolysin produced by S . marcescens . The sensitivity of the cell lines CHO, HeLa, HEp-2, Vero, BHK-21, MA 104 and J774 to the cytotoxin was determined by the cell viability assay using neutral red . CHO and HEp-2 were highly sensitive, with massive cellular death after 1 h of treatment, followed by BHK-21, HeLa, Vero and J774 cells, while MA 104 was insensitive to the toxin . Cytotoxin induced morphological changes such as cell rounding with cytoplasmic retraction and nuclear compactation which were evident 15 min after the addition of cytotoxin . The cytotoxic assays show that 15 min of treatment with the cytotoxin induced irreversible intoxication of the cells, determined by loss of cell viability . Concentrations of 2 CD50 (0.56 g/ml) of purified cytotoxin did not present any hemolytic activity, showing that the cytotoxin is distinct from S . marcescens hemolysin . Antisera prepared against S . marcescens cytotoxin did not neutralize the cytotoxic activity of VT1, VT2 or CNF toxin, indicating that these toxins do not share antigenic determinants with cytotoxin . Moreover, we did not detect gene sequences for any of these toxins in S . marcescens by PCR assay . These results suggest that S . marcescens cytotoxin is not related to any of these toxins from E . coli.

Wien Klin Wochenschr, 2002 Dec 30, 114(23-24), 1017 - 22
Serratia marcescens in the neonatal intensive care unit: re-emphasis of the potentially devastating sequelae; Berger A et al.; BACKGROUND: It is known that infections with Serratia marcescens can take a progressive course in preterm infants and that meningoencephalitis with this pathogen exhibits an extremely bad neurologic prognosis . METHODS AND RESULTS: We report on five cases of septicemia with Serratia marcescens in preterm infants during a nosocomial outbreak . Three patients developed meningoencephalitis with brain abscesses . Mild clinical and laboratory findings of infection contrasted with destructive findings on MRI scan . All five patients survived, those with isolated bacteremia without neurologic sequelae . CONCLUSION: When Serratia marcescens is isolated from any source in a neonatal intensive care unit, preventive measures including strict hygiene and cohorting of infants must be implemented immediately since this pathogen seems to exhibit specific affinity for the central nervous system and Serratia marcescens meningoencephalitis takes a progressive and destructive course despite antibiotic therapy.

Microbiology, 2003 Feb, 149(Pt 2), 471 - 83
Quorum-sensing-directed protein expression in Serratia proteamaculans B5a; Christensen AB et al.; N-Acyl-L-homoserine-lactone-producing Serratia species are frequently encountered in spoiling foods of vegetable and protein origin . The role of quorum sensing in the food spoiling properties of these bacteria is currently being investigated . A set of luxR luxI homologous genes encoding a putative quorum sensor was identified in the N-(3-oxo-hexanoyl)-L-homoserine lactone (3-oxo-C6-HSL)-producing Serratia proteamaculans strain B5a . The 3-oxo-C6-HSL synthase SprI showed 79 % similarity with EsaI from Pantoea stewartii and the putative regulatory protein SprR was 86 % similar to the SpnR of Serratia marcescens . Proteome analysis suggested that the presence of at least 39 intracellular proteins was affected by the 3-oxo-C6-HSL-based quorum sensing system . The lipB-encoded secretion system was identified as one target gene of the quorum sensing system . LipB was required for the production of extracellular lipolytic and proteolytic activities, thus rendering the production of food-deterioration-relevant exoenzymes indirectly under the control of quorum sensing . Strain B5a caused quorum-sensing-controlled spoilage of milk . Furthermore, chitinolytic activity was controlled by quorum sensing . This control appeared to be direct and not mediated via LipB . The data presented here demonstrate that quorum-sensing-controlled exoenzymic activities affect food quality.

Jpn J Antibiot, 2002 Dec, 55(6), 844 - 54
{Antibacterial activities of fosfomycin against several fresh clinical isolates--comparison of the test methods for antibacterial activity}; Hara T et al.; In vitro antibacterial activity of fosfomycin was evaluated by various methods . Strains of methicillin-sensitive Staphylococcus aureus, methicillin-sensitive coagulase-negative Staphylococci and Escherichia coli were much more susceptible when glucose-6-phosphate was added to the test medium, but strains of Serratia marcescens and Pseudomonas aeruginosa were not affected . Nutrient agar instead of Mueller-Hinton agar allowed to exhibiting the higher activity of fosfomycin against all the species tested . The activity of fosfomycin was as equivalent or superior to those of cefazolin, cefmetazole, cefotiam and piperacillin . The susceptibility of strains isolated during 2000 to 2001 to fosfomycin was almost the same as that of the isolates reported in 1975 . Fosfomycin was considered to show high efficacy in several infections, since it has maintained its favorable antibacterial activities against several bacterial species for more than 20 years after the first application to clinical practice.

J Bacteriol, 2003 Mar, 185(6), 1808 - 16
Purification and in vitro characterization of the Serratia marcescens NucC protein, a zinc-binding transcription factor homologous to P2 Ogr; McAlister V et al.; NucC is structurally and functionally homologous to a family of prokaryotic zinc finger transcription factors required for late gene expression in P2- and P4-related bacteriophages . Characterization of these proteins in vitro has been hampered by their relative insolubility and tendency to aggregate . We report here the successful purification of soluble, active, wild-type NucC protein . Purified NucC exhibits site-specific binding to a conserved DNA sequence that is located upstream of NucC-dependent Serratia marcescens promoters and the late promoters of P2-related phages . This sequence is sufficient for binding of NucC in vitro . NucC binding to the S . marcescens nuclease promoter P(nucA) and to the sequence upstream of the P2 late promoter P(F) is accompanied by DNA bending . NucC protects about 25 nucleotides of the P(F) upstream region from DNase I digestion, and RNA polymerase protects the promoter region only in the presence of NucC . Template DNA, RNA polymerase holoenzyme, and purified NucC are the only macromolecular components required for transcription from P(F) in vitro.

J Bacteriol, 2003 Mar, 185(6), 1776 - 82
Uptake of N,N'-diacetylchitobiose {(GlcNAc)2} via the phosphotransferase system is essential for chitinase production by Serratia marcescens 2170; Uchiyama T et al.; The chiR gene of Serratia marcescens 2170, encoding a LysR-type transcriptional activator, was identified previously as an essential factor for expression of chitinases and a chitin-binding protein, CBP21 . To identify other genes that are essential for chitinase production, transposon mutagenesis with mini-Tn5Km1 was carried out, and 25 mutants that were unable to produce chitinases and CBP21 were obtained . Analysis of the mutated gene of one of the mutants, N22, revealed the presence of a pts operon in this bacterium, and a mutation was found in ptsI in the operon . In addition to its inability to produce chitinase, N22 did not grow well on N-acetyl-D-glucosamine (GlcNAc), (GlcNAc)(2), and some other carbon sources, most of which were phosphotransferase system (PTS) sugars . Thus, the inability to produce chitinase was assumed to be caused by the defect in uptake of (GlcNAc)(2) via the PTS, considering that (GlcNAc)(2) is the minimal substrate for chitinase induction and the major product of chitin hydrolysis by chitinases of this bacterium . To confirm this assumption, the chb operon, encoding the (GlcNAc)(2)-specific enzyme II permease, was cloned by reference to its Escherichia coli counterpart, and the Serratia chb operon was shown to comprise chbB, chbC, bglA, chbR, and chbG . Disruption of chbC drastically reduced production of chitinases and CBP21 and impaired growth on colloidal chitin . These results indicate that uptake of (GlcNAc)(2) is mediated by the PTS and that the (GlcNAc)(2)-specific enzyme II permease constitutes its major pathway . Since (GlcNAc)(2) uptake is essential for induction of chitinases and CBP21 production, (GlcNAc)(2) appears to be the key molecule in recognition and utilization of chitin by S . marcescens.

J Agric Food Chem, 2003 Mar 12, 51(6), 1701 - 5
Synthesis of new glycosides by transglycosylation of N-acetylhexosaminidase from Serratia marcescens YS-1; Kurakake M et al.; Serratia marcescens YS-1, a chitin-degrading microorganism, produced mainly N-acetylhexosaminidase . The purified enzyme had an optimal pH of approximately 8-9 and remained stable at 40 degrees C for 60 min at pH 6-8 . The optimum temperature was around 50 degrees C, and enzyme activity was relatively stable below 50 degrees C . YS-1 N-acetylhexosaminidase hydrolyzed p-nitrophenyl beta-N-acetylgalactosamide by 28.1% relative to p-nitrophenyl beta-N-acetylglucosamide . The N-acetylchitooligosaccharides were hydrolyzed more rapidly, but the cellobiose and chitobiose of disaccharides that had the same beta-1,4 glycosidic bond as di-N-acetylchitobiose were not hydrolyzed . YS-1 N-acetylhexosaminidase efficiently transferred the N-acetylglucosamine residue from di-N-acetylchitobiose (substrate) to alcohols (acceptor) . The ratio of transfer to methanol increased to 86% in a reaction with 32% methanol . N-Acetylglucosamine was transferred to the hydroxyl group at C1 of monoalcohols . A dialcohol was used as an acceptor when the carbon number was more than 4 and a hydroxyl group existed on each of the two outside carbons . Sugar alcohols with hydroxyl groups in all carbon positions were not proper acceptors.

J Environ Biol, 2002 Jan, 23(1), 57 - 9
Uptake of nickel (II) by Serratia marcescens; Kannan A et al.; Bioaccumulation and biosorption of various nickel salts by Serratia marcescens (NCIM 2078) were investigated Biosorption of nickel was found maximum for the nickel nitrate and nickel chloride as 28.08 and 25.51 mg-1 nickel was obtained in dry biomass of S . marcescens, respectively . The possible role of pigment prodigiosin in uptake of nickel is discussed.

J Dairy Sci, 2003 Jan, 86(1), 127 - 32
Purification and partial characterization of psychrotrophic Serratia marcescens lipase; Abdou AM; Serratia marcescens isolated from raw milk was found to produce extracellular lipase . The growth of this organism could contribute to flavor defects in milk and dairy products . Serratia marcescens was streaked onto spirit blue agar medium, and lipolytic activity was detected after 6 h at 30 degrees C and after 12 h at 6 degrees C . The extracellular crude lipase was collected after inoculation of the organism into nutrient broth and then into skim milk . The crude lipase was purified to homogeneity by ion-exchange chromatography and gel filtration . The purified lipase had a final recovered activity of 45.42% . Its molecular mass was estimated by SDS-PAGE assay to be 52 kDa . The purified lipase was characterized; the optimum pH was likely between 8 and 9 and showed about 70% of its activity at pH 6.6 . The enzyme was very stable at pH 8 and lost about 30% of its activity after holding for 24 h at 4 degrees C in buffer of pH 6.6 . The optimum temperature was observed at 37 degrees C and exhibited high activity at 5 degrees C . The thermal inactivation of S . marcescens lipase was more obvious at 80 degrees C; it retained about 15% of its original activity at 80 degrees C and was completely inactivated after heating at 90 degrees C for 5 min . Under optimum conditions, activity of the enzyme was maximum after 6 min . The Michaelis-Menten constant was 1.35 mM on tributyrin . The enzyme was inhibited by a concentration more than 6.25mM . Purified lipase was not as heat-stable as other lipases from psychrotrophs, but it retained high activity at 5 degrees C . At pH 6.6, the pH of milk, purified lipase showed some activity and stability . Also, the organism demonstrated lipolytic activity at 6 degrees C after 12 h . Therefore, S . marcescens and its lipase were considered to cause flavor impairment during cold storage of milk and dairy products.

Biol Pharm Bull, 2003 Mar, 26(3), 391 - 3
Multidrug resistance in Serratia marcescens and cloning of genes responsible for the resistance; Chen J et al.; Six clinically isolated strains of Serratia marcescens were tested for their drug resistance . All showed fairly high resistance to many antimicrobial agents tested including norfloxacin, streptomycin, ampicillin, erythromycin, tetracycline, chloramphenicol, and antimicrobial dyes . Using the drug-hypersensitive strain of Escherichia coli KAM32 as the host, we cloned the genes responsible for multidrug resistance from chromosomal DNA of one of the strains of S . marcescens, NUSM8906 . We obtained 28 hybrid plasmids that made host cells resistant to several antimicrobial agents . Many of the transformants harboring each of the plasmids showed multidrug resistance, and some showed resistance to specific drugs . The hybrid plasmids were classified into several groups based on their drug specificity . It appears that each class of plasmid carries different types of drug resistance genes . Analysis of such genes will reveal the multiple mechanisms involved in multidrug resistance in S . marcescens.

Dev Comp Immunol, 2003 Mar, 27(3), 189 - 96
Manduca sexta lipopolysaccharide-specific immulectin-2 protects larvae from bacterial infection; Yu XQ et al.; We previously reported the isolation of a lipopolysaccharide (LPS)-specific immulectin-2 from the tobacco hornworm, Manduca sexta {J . Biol . Chem . 275 (2000) 37373} . Immulectin-2 is a C-type lectin that is present at a constitutively low level in hemolymph of naive larvae, and its synthesis is induced after injection of Gram-negative bacteria or LPS . Immulectin-2 contains two carbohydrate recognition domains . It binds to LPS and stimulates prophenoloxidase activation in plasma . In this paper, we focus on properties of carbohydrate recognition domain-2 of immulectin-2 and the biological functions of immulectin-2 in immune responses . The carboxyl-terminal carbohydrate recognition domain (CRD2) of immulectin-2 was able to bind bacterial LPS . Binding of recombinant CRD2 to LPS stimulated activation of prophenoloxidase in plasma . Injection of antiserum against immulectin-2 into M . sexta larvae inhibited clearance of a Gram-negative bacterial pathogen, Serratia marcescens, and decreased survival of infection . These results suggest that immulectin-2 plays an important role in the immune system of M . sexta, and helps to protect the animal from Gram-negative bacterial infections.

FEBS Lett, 2003 Feb 11, 536(1-3), 41 - 4
Phosphatase activity of non-heme chloroperoxidase from the bacterium Serratia marcescens; Preobrazhenskaya YV et al.; Haloperoxidases are enzymes capable of formation of carbon-halogen bonds in the presence of hydrogen peroxide and halide ions . A mechanism of halogenation catalyzed by heme- and metal-independent bacterial haloperoxidases differs from other representatives of this group of enzymes . Here we report for the first time that bacterial non-heme haloperoxidases possess a phosphatase activity . Chloroperoxidase from Serratia marcescens W 250 purified up to homogeneity is shown to catalyze p-nitrophenylphosphate hydrolysis (K(m) value, 1.8+/-0.1 mM at pH 5.7) . The reaction is activated by Mg(2+) and F(-), and is inhibited by WO(4)(2-), tartrate, acetate and phosphate anions . The irreversible inhibition by phenylmethanesulfonyl fluoride, modifier of serine residue in active site, decreases in the presence of phosphate ions . A mechanism of phosphoesters hydrolysis by non-heme haloperoxidases is proposed.

Wei Sheng Wu Xue Bao, 1999 Jun, 39(3), 275 - 8
{Fraction P isolated from the ribosomes of Serratia odorifera and its tumor inhibiting effect}; Wang X et al.; A protein(component P) with molecular weight of 16 kD was isolated by the method of preparation electrophoresis from the ribosomes of Serratia odorifera, which were obtained by the method of differential centrifugation . This protein showed specific immune response reactivity with the antiserum of the ribosomes mentioned above . Meanwhile, component P showed apparent protective function for QGY-tumorcharged nude mouse and different ways of giving medicine . It was evident from study results that component P isolated from the ribosomes of Serratia odorifera showed a direct function for tumor growth inhibition and it was the effective component of the ribosomes of Serratia odorifera.

N Engl J Med, 2003 Jan 16, 348(3), 214 - 20
Pseudomonas aeruginosa and Serratia marcescens contamination associated with a manufacturing defect in bronchoscopes; Kirschke DL et al.; BACKGROUND: Several outbreaks and pseudo-outbreaks of Pseudomonas aeruginosa and Serratia marcescens infections associated with bronchoscopy have been reported . We conducted an investigation of P . aeruginosa and S . marcescens isolates related to bronchoscopy at a community hospital . METHODS: We reviewed the records of all bronchoscopic procedures at the community hospital from July to October 2001 . Environmental samples were obtained . Pulsed-field gel electrophoresis (PFGE) was performed on isolates of P . aeruginosa . RESULTS: From July 1 to October 31, 2001, 66 bronchoscopic procedures were performed in 60 patients, and 43 specimens were obtained for bacterial culture; 20 of the specimens (47 percent) were positive for P . aeruginosa . Six (30 percent) of the specimens that were positive for P . aeruginosa also yielded S . marcescens . All 20 P . aeruginosa isolates were associated with procedures performed with three of four new bronchoscopes from the same manufacturer . Contrary to manufacturing specifications, the biopsy-port caps on all four bronchoscopes were easily removable, and P . aeruginosa was cultured from the biopsy ports of the three implicated bronchoscopes . The PFGE patterns of P . aeruginosa isolates from the bronchoscopes, patients, and two environmental samples were indistinguishable . One patient was hospitalized with P . aeruginosa pneumonia 11 days after bronchoscopy . The manufacturer reported a design change instituted in 1997, and production problems may have resulted in the distribution of bronchoscopes that did not meet specifications . CONCLUSIONS: We documented contamination of bronchoscopes with P . aeruginosa and S . marcescens and possible infection of patients at a community hospital as a result of the inadequate disinfection of bronchoscopes because of a manufacturing defect .

Gene, 2003 Jan 2, 302(1-2), 185 - 92
The Serratia marcescens bioH gene encodes an esterase; Akatsuka H et al.; The 3.9 kb chromosomal DNA was cloned from Serratia marcescens Sr41, which confers on Escherichia coli cells a phenotype of clear halo formation on tributyrin agar plates . Three complete open reading frames (ORFs) were identified in the inserted DNA, and one ORF was demonstrated to encode a 28 kDa protein of 255 amino acids related to esterase activity . Interestingly, the ORF was 70% identical to a product of the E . coli bioH gene, which lies at a locus separated from the bioABFCD operon and acts in the early steps of the biotin synthetic pathway before pimeloyl-CoA synthesis . This gene complemented a bioH-deficient mutation of E . coli . From the sequence analysis, BioH is presumed to be a serine hydrolase, which belongs to the alpha/beta hydrolase-fold family comprising a wide variety of hydrolases including esterases . A catalytic triad composed of a nucleophilic residue (Ser80), an acidic residue (Asp206), and histidine (His234) was conserved in BioH, and the nucleophilic residue Ser, a catalytic center, was situated in the consensus sequence of G-X-S-X-G-G, a nucleophile elbow . Although the enzymatic function of BioH is not yet elucidated, the bioH gene products from S . marcescens and E . coli show esterase activity, which may imply the hydrolysis of a precursor leading to pimeloyl-CoA ester . The esterase activity of BioH and its CoA binding activity recently reported agree with a current hypothesis of pimeloyl-CoA ester synthesis from CoA and acylester derivatives including an acyl-carrier protein.

J Infect Chemother, 2002 Dec, 8(4), 368 - 70
Rapid pulsed-field gel electrophoresis technique for determination of genetic diversity of Serratia marcescens; Ishii Y et al.; Seventeen Serratia marcescens strains were isolated from patients admitted to a hospital in the Tokyo metropolitan area . In order to study their genetic diversity, pulsed-field gel electrophoresis (PFGE) was performed . Clear bands were not observed by the standard PFGE technique following the instruction manual from the company . To obtain clear results, it was necessary to include some additional steps to the preparation of PFGE samples . We added an inactivation step for DNase using formaldehyde, and the bacterial strains were embedded in thinner plug molds than usual . These modifications were effective with all strains, and the complete PFGE pattern was obtained in the samples treated with formaldehyde and using thin plug molds . We established a rapid method to obtain a high-quality PFGE result for S . marcescens.

Curr Microbiol, 2003 Feb, 46(2), 151 - 3
The survival of ingested Serratia marcescens in houseflies (Musca domestica L.) after electrocution with electric fly killers; Cooke EA et al.; Electric fly killers (EFKs) are commonly used to control flying insects that enter food establishments . For establishment of the incidence of pathogen-bearing insects in food establishments, insect samples obtained from EFK trays could be used . The principal difficulty with this approach is that the survival time of microorganisms on or within insect corpses after electrocution is unknown . This study determined the survival of Serratia marcescens (as a representative of the enteric bacteria) within houseflies following their electrocution by a commercial EFK . S . marcescens was successfully ingested by houseflies and survived on and within the corpses after electrocution for up to 5 weeks . Maximal levels of bacteria were recovered 24 h postelectrocution . The study also demonstrates the ability of ingested S . marcescens to out-compete resident microbial flora within houseflies . The findings are intended to pave the way for further research to determine the incidence of pathogen-laden flying insects in food establishments.

Mol Microbiol, 2003 Jan, 47(2), 303 - 20
Phosphate availability regulates biosynthesis of two antibiotics, prodigiosin and carbapenem, in Serratia via both quorum-sensing-dependent and -independent pathways; Slater H et al.; Serratia sp . ATCC 39006 produces two secondary metabolite antibiotics, 1-carbapen-2-em-3-carboxylic acid (Car) and the red pigment, prodigiosin (Pig) . We have previously reported that production of Pig and Car is controlled by N-acyl homoserine lactone (N-AHL) quorum sensing, with synthesis of N-AHLs directed by the LuxI homologue SmaI, and is also regulated by Rap, a member of the SlyA family . We now describe further characterization of the SmaI quorum-sensing system and its connection with other regulatory mechanisms . We show that the genes responsible for biosynthesis of Pig, pigA-O, are transcribed as a single polycistronic message in an N-AHL-dependent manner . The smaR gene, transcribed convergently with smaI and predicted to encode the LuxR homologue partner of SmaI, was shown to possess a negative regulatory function, which is uncommon among the LuxR-type transcriptional regulators . SmaR represses transcription of both the pig and car gene clusters in the absence of N-AHLs . Specifically, we show that SmaIR exerts its effect on car gene expression via transcriptional control of carR, encoding a pheromone-independent LuxR homologue . Transcriptional activation of the pig and car gene clusters also requires a functional Rap protein, but Rap dependency can be bypassed by secondary mutations . Transduction of these suppressor mutations into wild-type backgrounds confers a hyper-Pig phenotype . Multiple mutations cluster in a region upstream of the pigA gene, suggesting this region may represent a repressor target site . Two mutations mapped to genes encoding pstS and pstA homologues, which are parts of a high-affinity phosphate transport system (Pst) in Escherichia coli . Disruption of pstS mimicked phosphate limitation and caused concomitant hyper-production of Pig and Car, which was mediated, in part, through increased transcription of the smaI gene . The Pst and SmaIR systems define distinct, yet overlapping, regulatory circuits which form part of a complex regulatory network controlling the production of secondary metabolites in Serratia ATCC 39006.

Infect Control Hosp Epidemiol, 2002 Dec, 23(12), 740 - 7
Serratia bacteremia in a large university hospital: trends in antibiotic resistance during 10 years and implications for antibiotic use; Choi SH et al.; OBJECTIVE: To identify antibiotic resistance trends and risk factors for resistance of Serratia species to third-generation cephalosporins . DESIGN: Retrospective survey of medical records . SETTING: A 2,200-bed, tertiary-care hospital . PATIENTS: One hundred twenty-two patients with Serratia bacteremia between January 1991 and June 2001 . METHODS: Infectious disease physicians collected data from medical records regarding patient demographics, underlying disease or condition, portal of entry, microorganism, antibiogram, complications, antibiotics received, and outcome . RESULTS: Among 122 Serratia isolates, 117 (95.9%) were Serratia marcescens and 110 (90.2%) were of nosocomial origin . During the study period, the 122 isolates showed a high rate of resistance to third-generation cephalosporins (45.9%) and extended-spectrum penicillins (56.6%) . The resistance rate to ciprofloxacin was 32.0% . The resistance rate to third-generation cephalosporins increased from 31.7% for 1991 to 1995 to 54.9% for 1996 to 1998 and 50.0% for 1999 to 2001 . In the multivariate analysis, prior use of a second-generation cephalosporin (adjusted odds ratio {OR}, 5.90; 95% confidence interval {CI90}, 1.41 to 24.6; P = .015) or a third-generation cephalosporin (OR, 3.26; CI95, 1.20 to 8.87; P = .020) was a strong independent risk factor for resistance to third-generation cephalosporins . The overall case-fatality rate was 25.4% (Serratia bacteremia-related case-fatality rate, 13.1%) . CONCLUSION: Prior use of a second- or third-generation cephalosporin was the most important risk factor for bacteremia with Serratia resistant to third-generation cephalosporins, suggesting the need for antibiotic control . The potential role of patient-to-patient spread could not be fully evaluated in this retrospective study.

Infect Control Hosp Epidemiol, 2002 Dec, 23(12), 733 - 9
An outbreak of Serratia marcescens bacteremia after general anesthesia; Sebert ME et al.; OBJECTIVE: To investigate an outbreak of Serratia marcescens bacteremia among patients after general anesthesia . DESIGN: A case-control study . SETTING: A 304-bed, pediatric teaching hospital . PATIENTS: Twenty-three pediatric patients who developed S . marcescens bacteremia within 2 weeks after general anesthesia between June 15 and September 22, 1999, were compared with 46 age-matched control-patients who had undergone procedures on the same clinical services of the hospital during the same period . RESULTS: Cases were distributed over a wide range of surgical services and were not correlated with exposure to any of the surgical, anesthesia, or nursing staff . Case-patients were significantly more likely than control-patients to have received cefazolin (odds ratio {OR}, 11.1; 90% confidence interval {CI90}, 1.9 to 24.3) or to have had perioperative placement of a central vascular catheter (OR, 4.2; CI90, 1.2 to 18.8) . The timing of the procedures of patients who subsequently developed S . marcescens bacteremia was significantly associated with the shifts of one or more of five operating room technicians (OR, 2.9 to 6.8) who were responsible for preparing intravenous fluids used both to reconstitute perioperatively administered antibiotics and to prime central vascular catheter assemblies . CONCLUSIONS: Our findings are consistent with a pattern of intermittent contamination due to periodic breaches in sterile technique, rather than a point-source of contamination . The unique challenges that such a procedural breakdown presents to an epidemiologic investigation are discussed . This outbreak stresses the importance of providing comprehensive training in antisepsis when multifunctional personnel are incorporated into an operating room work environment.

Appl Environ Microbiol, 2003 Jan, 69(1), 285 - 9
Elevated abundance of bacteriophage infecting bacteria in soil; Ashelford KE et al.; Here we report the first direct counts of soil bacteriophage and show that substantial populations of these viruses exist in soil (grand mean = 1.5 x 10(7) g(-1)), at least 350-fold more than the highest numbers estimated from traditional viable plaque counts . Adding pure cultures of a Serratia phage to soil showed that the direct counting methods with electron microscopy developed here underestimated the added phage populations by at least eightfold . So, assuming natural phages were similarly underestimated, virus numbers in soil averaged 1.5 x 10(8) g(-1), which is equivalent to 4% of the total population of bacteria . This high abundance was to some extent confirmed by hybridizing colonies grown on Serratia and Pseudomonas selective media with cocktails of phage infecting these bacteria . This showed that 8.9 and 3.9%, respectively, hybridized with colonies from the two media and confirmed the presence of phage DNA sequences in the cultivable fraction of the natural population . Thus, soil phage, like their aquatic counterparts, are likely to be important in controlling bacterial populations and mediating gene transfer in soil.

Anal Chem, 2002 Dec 15, 74(24), 6191 - 9
Analysis of microbial mixtures by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; Wahl KL et al.; Many different laboratories are currently developing mass-spectrometric techniques to analyze and identify microorganisms . However, minimal work has been done with mixtures of bacteria . To demonstrate that microbial mixtures could be analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), mixed bacterial cultures were analyzed in a double-blind fashion . Nine different bacterial species currently in our MALDI-MS fingerprint library were used to generate 50 different simulated mixed bacterial cultures similar to that done for an initial blind study previously reported (Jarman, K . H.; Cebula, S . T.; Saenz, A . J.; Petersen, C . E.; Valentine, N . B.; Kingsley, M . T.; Wahl, K . L . Anal . Chem . 2000, 72, 1217-1223) . The samples were analyzed by MALDI-MS with automated data extraction and analysis algorithms developed in our laboratory . The components present in the sample were identified correctly to the species level in all but one of the samples . However, correctly eliminating closely related organisms was challenging for the current algorithms, especially in differentiating Serratia marcescens, Escherichia coli, and Yersinia enterocolitica, which have some similarities in their MALDI-MS fingerprints . Efforts to improve the specificity of the algorithms are in progress.

Int J Syst Evol Microbiol, 2002 Nov, 52(Pt 6), 2281 - 9
Characterization of Serratia isolates from soil, ecological implications and transfer of Serratia proteamaculans subsp . quinovora Grimont et al . 1983 to Serratia quinivorans corrig., sp . nov; Ashelford KE et al.; Eleven strains of Serratia were isolated from different soils and the guts of invertebrates and characterized by their sensitivity to eight indigenous bacteriophages . They were also classified according to bacteriocin production and sensitivity, BiOLOG plate and API 20E strip profiles and 16S rRNA sequence information . One strain was thus identified as Serratia plymuthica, another as Serratia fonticola . The remaining strains were shown to be closely related to Serratia proteamaculans subsp . quinovora Grimont et al . 1983 after DNA-DNA cross-hybridization demonstrated relatedness greater than 70% with the type strain of this subspecies . From an ecological perspective, our results illustrated the wide variation in sensitivity that closely related Serratia strains have towards various indigenous soil phages and that these phages have broad host ranges within the genus . Furthermore, the phage and bacteriocin interactions within the Serratia strains examined were intricate and did not reflect phylogenetic relationships . These results together imply that complex interactions will occur in soil within the natural community of Serratia strains and their bacteriophages . DNA-DNA cross-hybridization and phenotypic characterization showed that S . proteamaculans subsp . quinovora strains formed a cohesive group at the species level . It is therefore concluded that these strains should be designated as Serratia quinivorans corrig., sp . nov.

Pediatr Emerg Care, 2002 Dec, 18(6), 433 - 5
Cervical necrotizing fasciitis caused by Serratia marcescens in a 2 year old; Newton CL et al.; We report an unusual, life-threatening complication of producing fulminant cervical necrotizing fasciitis in a previously healthy 2-year-old girl . We reviewed the literature for necrotizing fasciitis in children and its morbidity, mortality, and treatment . This case illustrates the necessity of prompt recognition and aggressive management in patients presenting with cervical necrotizing fasciitis.

J Bacteriol, 2003 Jan, 185(1), 80 - 8
The SecB chaperone is bifunctional in Serratia marcescens: SecB is involved in the Sec pathway and required for HasA secretion by the ABC transporter; Sapriel G et al.; HasA is the secreted hemophore of the heme acquisition system (Has) of Serratia marcescens . It is secreted by a specific ABC transporter apparatus composed of three proteins: HasD, an inner membrane ABC protein; HasE, another inner membrane protein; and HasF, a TolC homolog . Except for HasF, the structural genes of the Has system are encoded by an iron-regulated operon . In previous studies, this secretion system has been reconstituted in Escherichia coli, where it requires the presence of the SecB chaperone, the Sec pathway-dedicated chaperone . We cloned and inactivated the secB gene from S . marcescens . We show that S . marcescens SecB is 93% identical to E . coli SecB and complements the secretion defects of a secB mutant of E . coli for both the Sec and ABC pathways of HasA secretion . In S . marcescens, SecB inactivation affects translocation by the Sec pathway and abolishes HasA secretion . This demonstrates that S . marcescens SecB is the genuine chaperone for HasA secretion in S . marcescens . These results also demonstrate that S . marcescens SecB is bifunctional, as it is involved in two separate secretion pathways . We investigated the effects of secB point mutations in the reconstituted HasA secretion pathway by comparing the translocation of a Sec substrate in various mutants . Two different patterns of SecB residue effects were observed, suggesting that SecB functions may differ for the Sec and ABC pathways.

J Ind Microbiol Biotechnol, 2002 Dec, 29(6), 373 - 5
Effects of anti-odor automobile air-conditioning system products on adherence of Serratia marcescens to aluminum; Drago GK et al.; Sixteen commercial products for use in automobile air-conditioning systems (ACS), most designated for abatement of malodors presumably of microbial origin, were examined for their potential to inhibit attachment and to detach cells of the Gram-negative bacterium Serratia marcescens on aluminum sections . Numbers of attached cells were appreciably reduced (>60%) following immersion in three alcohol-type and two acrylic-coating-type products . Several products had essentially no effect on the attached cells . Most of the products indicated for alleviation of associated microbial odors from ACS provided only short-term effects . When products were coated onto aluminum prior to exposure to the cells, water-insoluble coatings appeared to provide more consistent inhibition of primary adherence of S . marcescens . The differences in degrees of primary adherence of a selected strain of S . marcescens to variously treated aluminum provided a rapid and reproducible assessment of potential antimicrobial efficacy of ACS products.

J Hosp Infect, 2002 Dec, 52(4), 263 - 7
Source, carriers, and management of a Serratia marcescens outbreak on a pulmonary unit; van der Vorm ER et al.; An outbreak of Serratia marcescens was seen on a pulmonary ward from September 1999 until September 2000 . During this period, there were two distinct clusters of S . marcescens isolation . In the first episode, September-October 1999, S . marcescens isolates with the same resistance pattern were isolated in 10 patients . PFGE (pulsed-field gel electrophoresis) following digestion with SpeI confirmed that these isolates were identical . After an initial decline in the number of isolates, the incidence rose again in March 2000 . The resistance pattern of these isolates differed from that in 1999 . PFGE showed that most of the isolates in 2000 were identical and had replaced the previous strain (strain 1) . In the second episode, January-August 2000, 26 patients were colonized with the subsequent strain (strain 2) . Three of these patients had serious clinical problems due to S . marcescens, two had bacteraemia and one empyema . In September 2000, strain 2 was also detected in stock solutions for inhalation therapy . After discontinuation of the use of stock solutions and emphasizing hygienic measures, the outbreak resolved . The majority (68%) of the patients positive for S . marcescens suffered from COPD (chronic obstructive pulmonary disease) . PFGE results suggest that several COPD patients were carriers of the same strain of S . marcescens for a prolonged time . Re-admission of these patients could have lead to re-introduction of the epidemic strains .

Spine, 2002 Dec 1, 27(23), E507 - 12
Serratia spondylodiscitis after elective lumbar spine surgery: a report of two cases; Hadjipavlou AG et al.; STUDY DESIGN: This report describes two cases of acute spondylodiscitis, caused by, complicating two different conditions: microdiscectomy for herniated nucleus pulposus and decompressing laminotomy for spinal stenosis . OBJECTIVE: To describe a rare and life-threatening spinal infection and discuss its successful management . SUMMARY OF BACKGROUND DATA: To our knowledge, no published reports in the English language have described this potentially devastating infection as a complication of elective noninstrumented discectomy or decompressive laminotomy . METHODS: Two cases of a very early onset of acute spondylodiscitis, caused by, after minimally invasive lumbar spine surgeries are presented . The elapsed time between these two complications was 1 week . The clinical presentation was characteristically stormy in both cases . On postoperative day 2, the patients developed high fever with intense chills and concomitant acute low back pain rapidly increasing in severity . The overall clinical appearance was alarming . The patients were carefully investigated immediately and scrutinized for possible origin of the infection . Treatment consisted of prompt intravenous antibiotics and surgical debridement . RESULTS: The history and clinical manifestations of postoperative spondylodiscitis were corroborated with magnetic resonance imaging findings and bacteriologic and hematologic laboratory examination . Blood cultures revealed as the responsible pathogenic microorganism . The source of the pathogens was contaminated normal saline used for surgical lavage . Both patients were able to completely resume their previous occupations after aggressive surgical debridement/irrigation and 3 months of antibiotic treatment . CONCLUSIONS: may become a potential pathogen, causing severe spinal infection after elective surgery . For prompt diagnosis and effective treatment of this life-threatening infection, one should maintain high index of suspicion and should not procrastinate in initiating treatment, which should consist of appropriate intravenous antibiotics and surgical debridement.

J Appl Microbiol, 1997 Mar, 82(3), 372 - 8
Identification and isolation of a bactericidal domain in chicken egg white lysozyme; Pellegrini A et al.; Chicken egg white lysozyme exhibits antimicrobial activity against both Gram-positive and Gram-negative bacteria . Fractionation of clostripain-digested lysozyme yielded a pentadecapeptide with antimicrobial activity but without muramidase activity . The peptide was isolated and its sequence found to be I-V-S-D-G-N-G-M-N-A-W-V-A-W-R (amino acids 98-112 of chicken egg white lysozyme) . A synthesized peptide of identical sequence had the same bactericidal activity as the natural peptide . Replacement of Trp 108 with tyrosine significantly reduced the antibacterial capacity of the peptide . By replacement of Trp 111 with tyrosine the antibacterial activity was lost . Replacement of Asn 106 with the positively charged arginine strongly increased the antibacterial capacity of I-V-S-D-G-N-G-M-N-A-W-V-A-W-R . The peptide I-V-S-D-G-N-G-M consisting of the eight amino acids of the N-terminal side had no bactericidal properties, whereas the peptide N-A-W-V-A-W-R of the C-terminal side retained some bactericidal activity . Replacement of asparagine 106 by arginine (R-A-W-V-A-W-R) increased the bactericidal activity considerably . The D enantiomer of R-A-W-V-A-W-R was as active as the L form against five of the tested bacteria, but substantially less active against Serratia marcescens, Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus lentus . For these bacterial species some stereospecific complementarity between receptor structures of the bacteria and the peptide can be assumed.

Perit Dial Int, 2002 Sep-Oct, 22(5), 573 - 81
Predictors of outcome following bacterial peritonitis in peritoneal dialysis; Krishnan M et al.; OBJECTIVE: No studies have been done to examine factors that predict the outcome of bacterial peritonitis during peritoneal dialysis (PD), beyond the contribution of the organism causing the peritonitis, concurrent exit-site or tunnel infection, and abdominal catastrophes . DESIGN: In this study we examined several clinical and laboratory parameters that might predict the outcome of an episode of bacterial peritonitis . Between March 1995 and July 2000, we identified 399 episodes of bacterial peritonitis in 191 patients on dialysis . RESULTS:There were 260 episodes of gram-positive peritonitis, 99 episodes of gram-negative peritonitis, and 40 episodes of polymicrobial peritonitis . Gram-positive peritonitis had a significantly higher resolution rate than either polymicrobial peritonitis or gram-negative peritonitis . Staphylococcus aureus episodes had poorer resolution than other gram-positive infections . Nonpseudomonal peritonitis had a better outcome than Pseudomonas aeruginosa episodes . Among all the gram-negative infections, Serratia marcescens had the worst outcome . Episodes associated with a purulent exit site had poor outcome only on univariate analysis . For those peritonitis episodes in which the PD fluid cell count was > 100/microL for more than 5 days, the nonresolution rate was 45.6%, compared to a 4.2% nonresolution rate when the cell count returned to 100/microL or less in less than 5 days . Those patients that had a successful outcome had been on continuous ambulatory PD for a significantly shorter period of time than those patients that had nonresolution . The nonresolution rate for those patients that had been on PD for more than 2.4 years was 24.4%, compared to 16.5% for those that had been on PD for less than 2.4 years (p = 0.05) . CONCLUSION: The duration of PD and the number of days the PD effluent cell count remained > 100/microL were the only factors that independently predicted the outcome of an episode of peritonitis . Caucasians seem to have a higher nonresolution (failure) rate compared to Blacks . Other variables, such as the number of peritonitis episodes before the episode in question, vancomycin-based initial empiric treatment, serum albumin level, total lymphocyte count and initial dialysate white blood cell count, age, sex, diabetes, previous renal transplantation, and the use of steroids did not affect the outcome of peritonitis.

Indian J Med Res, 2000 Nov, 112, 186 - 90
Purification & characterisation of haemolysin from Serratia marcescens B-91; Tiwari RP et al.; BACKGROUND & OBJECTIVES: Serratia marcescens an opportunistic human pathogen, is frequently encountered in a variety of debilitating diseases . Relatively little is known about its virulence traits though most clinical isolates secrete a distinct haemolysin which is considered as a useful marker for pathogenicity of Serratia . In this study purification and characterisation of S . marcescens B-91 haemolysin have been attempted . METHODS: S . marcescens B-91 haemolysin was purified to homogeneity from the growth medium using ammonium sulphate fractional precipitation and gel filtration through Sephadex G-75 column . Homogeneity was determined by gel electrophoresis and purified haemolysin was tested for its stability and other characteristics . RESULTS: The haemolysin was characterised to be a 45 kDa molecular weight protein on SDS-polyacrylamide gel electrophoresis . It was inactivated at 60-100 degrees C within 30 min, and on overnight treatment with 2 per cent formaldehyde . It was also susceptible to the action of pronase, protease and trypsin . INTERPRETATION & CONCLUSIONS: The results indicate that the fragile stability of S . marcescens haemolysin is dependent on the storage temperature . The purified haemolysin can be used for understanding the role of haemolysin in the pathogenesis of S . marcescens and also for evaluation of immunoprophylactic activity.

Appl Environ Microbiol, 2002 Dec, 68(12), 6146 - 51
Construction of DNA-shuffled and incrementally truncated libraries by a mutagenic and unidirectional reassembly method: changing from a substrate specificity of phospholipase to that of lipase; Song JK et al.; A method of mutagenic and unidirectional reassembly (MURA) that can generate libraries of DNA-shuffled and randomly truncated proteins was developed . The method involved fragmenting the template gene(s) randomly by DNase I and reassembling the small fragments with a unidirectional primer by PCR . The MURA products were treated with T4 DNA polymerase and subsequently with a restriction enzyme whose site was located on the region of the MURA primer . The N-terminal-truncated and DNA-shuffled library of a Serratia sp . phospholipase A(1) prepared by this method had an essentially random variation of truncated size and also showed point mutations associated with DNA shuffling . After high-throughput screening on triglyceride-emulsified plates, several mutants exhibiting absolute lipase activity (NPL variants) were obtained . The sequence analysis and the lipase activity assay on the NPL variants revealed that N-terminal truncations at a region beginning with amino acids 61 to 71, together with amino acid substitutions, resulted in the change of substrate specificity from a phospholipase to a lipase . We therefore suggest that the MURA method, which combines incremental truncation with DNA shuffling, can contribute to expanding the searchable sequence space in directed evolution experiments.

Mikrobiologiia, 2002 Sep-Oct, 71(5), 635 - 8
{The accumulation of proteins with chitinase activity in the culture media of the parent and mutant Serratia marcescens strain grown in the presence of mitomycin C}; Iusupova DV et al.; The study of the accumulation pattern of extracellular proteins with chitinase activity in the parent Serratia marcescens strain Bu 211 (ATCC 9986) grown in the presence of mitomycin C and its mutant strain with the constitutive synthesis of chitinases grown in the absence of the inducer showed that chitinase activity appeared in the culture liquids of both strains at the end of the exponential phase (4 h of growth) and reached a maximum in the stationary phase (18-20 h of growth) . The analysis of the culture liquids (12 h of growth) by denaturing electrophoresis in PAAG followed by the protein renaturation step revealed the presence of four extracellular proteins with chitinase activity and molecular masses of 21, 38, 52, and 58 kDa.

Nippon Rinsho, 2002 Nov, 60(11), 2156 - 60
{Serratia}; Hirakata Y; Serratia species, in particular, Serratia marcescens frequently causes bloodstream infections . Recently, several outbreaks of nosocomial bloodstream infections due to S . marcescens have been reported in Japan . Although Serratia is an opportunistic pathogen, the organism can develop endotoxin shock and multiple organ failure because of being gram-negative rod when a number of bacteria invade the bloodstream . Serratia in the intestinal tract can invade bloodstream endogenously in compromised hosts . However, the possible causes of an outbreak are contamination of antiseptics, and consequent contamination of transfusion . To prevent outbreaks of S . marcescens bloodstream infection, management of antiseptics and transfusion in addition to contact precaution should be taken.

FEMS Microbiol Lett, 2002 Nov 5, 216(2), 211 - 6
The wavB gene of Vibrio cholerae and the waaE of Klebsiella pneumoniae codify for a beta-1,4-glucosyltransferase involved in the transfer of a glucose residue to the L-glycero-D-manno-heptose I in the lipopolysaccharide inner core; Izquierdo L et al.; Vibrio cholerae WavB protein showed some similarity to WaaE of Klebsiella pneumoniae and Serratia marcescens . From previous data obtained by us and by chemical analyses of a K . pneumoniae non-polar waaE mutant from strain 889 (08:K69), its lipopolysaccharide (LPS) core structure has recently been elucidated . We demonstrated that WaaE is a beta-1,4-glucosyltransferase involved in the transfer of a glucose residue to the L-glycero-D-manno-heptose I in the LPS inner core . Complementation of this K . pneumoniae non-polar waaE mutant with gene wavB obtained, either from V . cholerae or V . mimicus, showed a full complementation either by chemical studies or by a biological test (susceptibility to non-immune serum) . The V . cholerae wavB gene is located in a putative core oligosaccharide (OS) gene cluster and the V . cholerae OS core structure showed the same beta-1,4-glucose residue attached to Hep I as is observed for the K . pneumoniae 889 OS core structure . No other glucose residue is found in the ligosaccharide core structure of K . pneumoniae 889 . We concluded that WavB protein is able to perform the same function as WaaE.

J Hosp Infect, 2002 Nov, 52(3), 175 - 80
An outbreak of Serratia marcescens infection in a special-care baby unit of a community hospital in United Arab Emirates: the importance of the air conditioner duct as a nosocomial reservoir; Uduman SA et al.; We report an outbreak of Serratia marcescens infection in a special-care baby unit (SCBU) of a university-affiliated community hospital in the United Arab Emirates . The outbreak involved 36 infants and lasted for 20 weeks . Seven of the colonized infants developed invasive illnesses in the form of bacteraemia (four cases), bacteraemic meningitis (two) and clinical sepsis (one) . Three other term infants had purulent conjunctivitis . There were five deaths with an overall mortality of 14% . S . marcescens was cultured from airflow samples from the air conditioning (AC) which was the reservoir of infection in this outbreak . Elimination of the nosocomial source and outbreak containment were eventually achieved by specialized robotic cleaning of the entire AC duct system of the SCBU . Strict adherence to the infection control policies was reinforced to prevent transmission of cross-infection .

Cornea, 2002 Nov, 21(8), 807 - 11
Effectiveness of mupirocin and polymyxin B in experimental Staphylococcus aureus, Pseudomonas aeruginosa, and Serratia marcescens keratitis; Moreau JM et al.; PURPOSE: The purpose of this study was to determine the effectiveness of mupirocin and polymyxin B, alone and in combination, in vitro and in vivo using rabbit models of, and keratitis . METHODS: Rabbit eyes were intrastromally injected with 1,000 colony-forming units (CFUs) of or or 100 CFUs of Rabbits were then treated with 2.7 mg/mL mupirocin, 10,000 U/mL polymyxin B, a mupirocin:polymyxin B combination, or 0.3% ciprofloxacin . Vehicle and untreated controls were also included . Treatment schedules depended on the strain injected . The number of CFUs was determined for all eyes after treatment . RESULTS: The mupirocin:polymyxin B combination was effective for all three genera both in vitro and in vivo . For keratitis, the mupirocin:polymyxin B combination was more effective than either drug alone and significantly reduced the log number of bacteria in the cornea by more than 3 logs compared with the vehicle or untreated controls (p <or= 0.0016) . For, the mupirocin:polymyxin B combination treatment significantly reduced the number of CFUs per cornea relative to the individual drugs, vehicle, or untreated controls (p <or= 0.016) . For, the mupirocin:polymyxin B combination therapy significantly reduced the number of bacteria in rabbit corneas relative to the individual drugs, vehicle, or untreated groups (p <or= 0.0001) . Therapy with the mupirocin:polymyxin B combination was equivalent to ciprofloxacin therapy (p = 0.80) . CONCLUSION: The mupirocin:polymyxin B combination was effective in treating experimental, and keratitis.

J Med Assoc Thai, 2002 Aug, 85 Suppl 2, S674 - 81
The outbreak of Serratia marcescens bacteremia in a pediatric ward, Siriraj Hospital 1997; Chokephaibulkit K et al.; Between October 20 and November 11, 1997, Serratia marcescens bacteremia was identified in 8 patients in a pediatric ward at Siriraj Hospital . The organism was isolated from 17 blood and 3 bone marrow specimens . The only common associated factor in these patients was that they all had received an intravenous fluid infusion . In the attempt to investigate the source of S . marcescens implicated in the outbreak, 108 specimens of intravenous fluid, 3 intravenous fluid bottle caps, 4 specimens from intravenous fluid tubing sets, 21 specimens of antiseptics used on the ward, 28 specimens of rectal swabs from patients on the ward, 1 sample of blood culture media prepared by the hospital for routine use, and 62 environmental specimens including hand swabs of the medical personnel, refrigerator, air conditioning, milk samples, room air, water sink, wooden splint and adhesive tape used to immobilize the intravenous access . Of 227 specimens sent for culture, S . marcescens was isolated from only one specimen collected from the in-use intravenous fluid given to a patient with Serratia bacteremia . S . marcescens was not found in any other surveillance culture . The 8 patients were placed under quarantine in the same room with an exclusive nursing team . With the investigation and intervention including monitoring for meticulous hand washing of the ward staff, the outbreak was stopped within 7 days . Although the investigation failed to discover the environmental reservoir of S . marcescens in this outbreak, the data suggested that intravenous fluid was probably the route of transmission and the medical personnel played an important role in spreading the infection.

Infection, 2002 Oct, 30(5), 277 - 81
Nosocomial neonatal outbreak of Serratia marcescens--analysis of pathogens by pulsed field gel electrophoresis and polymerase chain reaction; Steppberger K et al.; BACKGROUND: We investigated an outbreak of Serratia marcescens in the neonatal intensive care unit (NICU) and the pediatric intensive care unit (ICU) of the University Children's Hospital Leipzig, Germany . PATIENTS AND METHODS: From September to November 1998 15 patients were infected or colonized by S . marcescens . During the outbreak swabs from eye, blood, throat and nose were taken from every patient hospitalized in the ICUs . RESULTS: In 15 cases (14 from the NICU and one from the pediatric ICU) the cultures yielded S . marcescens . All strains were investigated by pulsed field gel electrophoresis (PFGE) as well as by polymerase chain reaction (PCR) fingerprinting . Both molecular typing methods revealed corresponding fingerprint patterns in all of the 15 isolates . Typing results of the outbreak-related isolates demonstrated that two epidemic strains of distinct genotypes were associated with cross-infections of a group of five and a group of ten patients, respectively . The three invasive and seven of the colonizing isolates were related genotypically . CONCLUSION: This survey shows that PCR and PFGE are comparable in respect to the discrimination and reproducibility for epidemiological studies of S . marcescens strains in nosocomial outbreaks . Genotypic fingerprinting of bacterial isolates is useful and important to limit nosocomial infections . Fingerprinting sources of nosocomial infections can be traced both by PFGE and PCR . All patients infected recovered completely and the nosocomial outbreak could be stopped rapidly.

Acta Microbiol Pol, 2002, 51(2), 131 - 7
The role of chitinese of Serratia marcescens in controlling the production of zearalenone by Fusarium graminearum; Aziz NH; An experiment was designed to determine the role of the chitinase of S . marcescens in controlling the production of zearalenone by F . graminearum isolated from diseased wheat plants . Fusarium graminearum, F . avenaceum, F . equiseti, F . culmorum, and F . solani were isolated from diseased wheat plant . F . graminearum culture materials were highly pathogenic for wheat seedlings, toxic to ducklings and produced high levels of zearalenone . S . marcescens was grown on the cell wall of F . graminearum and its components, chitin and laminarin as a sole carbon source . The release of N-acetyl-D-glucosamine from chitin, F . graminearum cell wall and living or drying mycelium indicated substrate degradation . S . marcescens applied to F . graminearum infested wheat kernels decreased greatly the occurrence of zearalenone after 4 weeks of incubation . F . graminearum culture materials treated with S . marcescens proved to be non-toxic to ducklings and wheat seed germination.

J Antimicrob Chemother, 2002 Oct, 50(4), 593 - 6
Fluoroquinolone resistance of Serratia marcescens: involvement of a proton gradient-dependent efflux pump; Kumar A et al.; OBJECTIVE: To determine the presence of a proton gradient-dependent efflux of fluoroquinolone drugs in Serratia marcescens . METHODS: Thirteen clinical isolates of S . marcescens were screened for resistance to four fluoroquinolones: ofloxacin, ciprofloxacin, norfloxacin and nalidixic acid by determining MICs . The presence of a proton gradient-dependent efflux mechanism was assessed using ethidium bromide accumulation assays . Drug accumulation studies for norfloxacin, ciprofloxacin and ofloxacin were performed to determine the drug specificity of efflux . Western transfer of cellular proteins, followed by immunodetection using anti-AcrA (Escherichia coli) antibodies were used to demonstrate the presence of a resistance-nodulation-cell division (RND) pump protein . PCR was used to identify a RND pump-encoding gene using primers for two conserved motifs within inner membrane components of RND proteins . A mutant strain of S . marcescens, UOC-67WL, was isolated by culturing the wild-type strain in the presence of ciprofloxacin in T-soy media and was subjected to the same studies as described above for the clinical isolates . RESULTS: Ethidium bromide accumulation assays confirmed the presence of a proton gradient-dependent efflux mechanism in S . marcescens . One clinical isolate, T-861, and the mutant strain, UOC-67WL, were found to efflux ciprofloxacin and ofloxacin . Western immunoblot results confirmed overexpression of an AcrA-like protein in T-861 and UOC-67WL . Sequencing of the PCR product showed the presence of a mexF-like gene, which is overexpressed in nfxC mutants of Pseudomonas aeruginosa . CONCLUSION: This study reports the presence of a proton gradient-dependent efflux mechanism in S . marcescens.

Mol Microbiol, 2002 Sep, 45(6), 1655 - 71
The LuxR family protein SpnR functions as a negative regulator of N-acylhomoserine lactone-dependent quorum sensing in Serratia marcescens; Horng YT et al.; Serratia marcescens SS-1 produces at least four N-acylhomoserine lactones (AHLs) which were identified using high-resolution mass spectrometry and chemical synthesis, as N-(3-oxohexanoyl) homo-serine lactone (3-oxo-C6-HSL), N-hexanoyl- (C6-HSL), N-heptanoyl (C7-HSL) and N-octanoyl- (C8-HSL) homoserine lactone . These AHLs are synthesized via the LuxI homologue SpnI, and regulate via the LuxR homologue SpnR, the production of the red pigment, prodigiosin, the nuclease, NucA, and a biosurfactant which facilitates surface translocation . spnR overexpression and spnR gene deletion show that SpnR, in contrast to most LuxR homologues, acts as a negative regulator . spnI overexpression, the provision of exogenous AHLs and spnI gene deletion suggest that SpnR is de-repressed by 3-oxo-C6-HSL . In addition, long chain AHLs antagonize the biosurfactant-mediated surface translocation of S . marcescens SS-1 . Upstream of spnI there is a gene which we have termed spnT . spnI and spnT form an operon and although database searches failed to reveal any spnT homologues, overexpression of this novel gene negatively affected both sliding motility and prodigiosin production.

Acta Crystallogr D Biol Crystallogr, 2002 Oct, 58(Pt 10 Pt 1), 1593 - 6 Epub 2002 Sep 26.
Application of the effects of ionic strength reducing agents in the purification and crystallization of chitinase A; Papanikolau Y et al.; The effects of ionic strength reducing agents may find a large number of applications . Based on these effects, we have redesigned the purification scheme of Chitinase A (ChiA) from Serratia marcescen . This scheme led to reproducibly crystallizable enzyme in both salting-in and salting-out conditions, which are presented here . Herein, we demonstrate some experimental applications of the ionic strength reducing agents theory and, in parallel, provide further evidence of the theory's correctness . Finally, we report a new crystal form produced recently in salting-in crystallization experiments . This form may allow the co-crystallization of ChiA mutants with longer substrates.

J Appl Microbiol, 2002, 93(4), 585 - 92
Comparative surface-to-hand and fingertip-to-mouth transfer efficiency of gram-positive bacteria, gram-negative bacteria, and phage; Rusin P et al.; AIMS: To determine the transfer efficiency of micro-organisms from fomites to hands and the subsequent transfer from the fingertip to the lip . METHODS AND RESULTS: Volunteers hands were sampled after the normal usage of fomites seeded with a pooled culture of a Gram-positive bacterium (Micrococcus luteus), a Gram-negative bacterium (Serratia rubidea) and phage PRD-1 (Period A) . Activities included wringing out a dishcloth/sponge, turning on/off a kitchen faucet, cutting up a carrot, making hamburger patties, holding a phone receiver, and removing laundry from the washing machine . Transfer efficiencies were 38.47% to 65.80% and 27.59% to 40.03% for the phone receiver and faucet, respectively . Transfer efficiencies from porous fomites were <0.01% . In most cases, M.luteus was transferred most efficiently, followed by phage PRD-1 and S . rubidea . When the volunteers' fingertips were inoculated with the pooled organisms and held to the lip area (Period B), transfer rates of 40.99%, 33.97%, and 33.90% occurred with M . luteus, S . rubidea, and PRD-1, respectively . CONCLUSIONS: The highest bacteral transfer rates from fomites to the hands were seen with the hard, non-porous surfaces . Even with low transfer rates, the numbers of bacteria transferred to the hands were still high (up to 10(6) cells) . Transfer of bacteria from the fingertip to the lip is similar to that observed from hard surfaces to hands . SIGNIFICANCE AND IMPACT OF THE STUDY: Infectious doses of pathogens may be transferred to the mouth after handling an everyday contaminated household object.

J Membr Biol, 2002 Sep 1, 189(1), 1 - 14
Serratia marcescens hemolysin (ShlA) binds artificial membranes and forms pores in a receptor-independent manner; Hertle R; Both the inactive and active conformations of the hemolysin/cytolysin of Serratia marcescens (ShlA) binds membranes of erythrocytes, but only active ShlA is able to form pores . ShlA is unable to lyse prokaryotic membranes . To determine the receptors of the binding and pore-forming domains of active cytolysin on eukaryotic membranes, artificial large unilamellar vesicles (LUVs) of various membrane compositions were examined . In the current study, it is shown that significant pore formation and lysis was achieved with binary phosphatidylcholine/phosphatidylserine (PS) liposomes . No proteinaceous receptor was needed for either binding or pore formation by ShlA . Membrane integration and pore-forming activity were enhanced by addition of phosphatidylethanolamine . Phosphatidylserine is negatively charged at physiologic pH and is almost absent in prokaryotic membranes . Hence, membrane binding and insertion of ShlA are highly dependent on phosphatidylserine, which targets the toxic activity to eukaryotic cell membranes without any need of a proteinaceous receptor . This may explain why prokaryotic membranes were found to be resistant against ShlA in a previous study.

Curr Microbiol, 2002 Oct, 45(4), 245 - 9
pH-dependent modulation of alkaline phosphatase activity in Serratia marcescens; Bhatti AR et al.; Serratia marcescens is an opportunistic pathogen responsible for causing nosocomial infections, corneal ulcer, necrotizing fasciitis, cellulites, and brain abscess . Alkaline phosphatase (APase) is believed to play an important role in the survival of several intracellular pathogens and their adaptation . We have studied the effect of low phosphate concentration and acid pH on the APase activities of S . marcescens . In a low phosphate medium, some strains of S . marcescens synthesize two different types of APases, a constitutive (CAPase) and an inducible (IAPase) . Both the CAPase and IAPase isoenzymes completely lost their enzyme activities at pH 2.3, within 10 min of incubation at 0 degrees C . Acid-treated IAPase isoenzymes I, II, III, and IV solutions when adjusted to pH 7.8 showed recovery of 70%, 52%, 72%, and 60% of the lost activities, respectively . When the pH of the CAPase reaction mixture was raised to pH 7.8, the enzyme activity regained only 5% of its initial activity . Variations in protein concentration also affected the pH-dependent reversible changes of the IAPase activity . The higher the protein concentration, the faster the inactivation of enzyme activity observed at acidic pH at 0 degrees C . Conversely, the lower the protein concentration, the higher the rate of reactivation of enzyme activity observed for IAPase at alkaline pH . Protein interaction studies revealed a lack of similarity between CAPase and IAPase, suggesting separate genetic origin of these potentially virulent genes of S . marcescens.

Infect Control Hosp Epidemiol, 2002 Aug, 23(8), 457 - 61
Nosocomial outbreak of Serratia marcescens in a neonatal intensive care unit; Assadian O et al.; OBJECTIVES: To investigate and describe an outbreak of Serratia marcescens in a neonatal intensive care unit (NICU) and to report the interventions leading to cessation of the outbreak . SETTING: A 2,168-bed, tertiary-care, university teaching hospital in Vienna, Austria, with an 8-bed NICU . DESIGN: We conducted a case-control study to identify risk factors for colonization and infection with S . marcescens . A case-patient was defined as any neonate in the NICU with a positive culture for S . marcescens between October 1, 2000, and February 28, 2001 . Polymerase chain reaction was applied to type isolates . METHODS: During unannounced observations, the NICU was examined and existing policies were reviewed . Staff were reinstructed in hand antisepsis and gloving policies . Admissions were halted on December 27 . During previously planned technical maintenance of the ward, the NICU was closed for 10 days and thorough aldehyde-based disinfection of the NICU was performed . RESULTS: Ten neonates met the case definition: 6 with infections (among them 3 with cerebral abscesses) and 4 with asymptomatic colonization . Previous antibiotic treatment of the mothers with cefuroxime was the single significant risk factor for colonization or infection (P = .028; odds ratio, 17; 95% confidence interval, 1.3 to 489.5) . CONCLUSIONS: S . marcescens can cause rapidly spreading outbreaks associated with fatal infections in NICUs . With aggressive infection control measures, such outbreaks can be stopped at an early stage . Affected neonates themselves may well be the source of cross-infection to other patients on the ward . Antibiotic treatment of mothers should be reevaluated to avoid unnecessary exposure to antibiotics with the potential of over-growth of resistant organisms.

Curr Biol, 2002 Jul 23, 12(14), 1209 - 14
Inducible antibacterial defense system in C . elegans; Mallo GV et al.; The term innate immunity refers to a number of evolutionary ancient mechanisms that serve to defend animals and plants against infection . Genetically tractable model organisms, especially Drosophila, have contributed greatly to advances in our understanding of mammalian innate immunity . Essentially, nothing is known about immune responses in the nematode Caenorhabditis elegans . Using high-density cDNA microarrays, we show here that infection of C . elegans by the Gram-negative bacterium Serratia marcescens provokes a marked upregulation of the expression of many genes . Among the most robustly induced are genes encoding lectins and lysozymes, known to be involved in immune responses in other organisms . Certain infection-inducible genes are under the control of the DBL-1/TGFbeta pathway . We found that dbl-1 mutants exhibit increased susceptibility to infection . Conversely, overexpression of the lysozyme gene lys-1 augments the resistance of C . elegans to S . marcescens . These results constitute the first demonstration of inducible antibacterial defenses in C . elegans and open new avenues for the investigation of evolutionary conserved mechanisms of innate immunity.

J Bacteriol, 2002 Sep, 184(17), 4690 - 8
Genomic variability of O islands encoding tellurite resistance in enterohemorrhagic Escherichia coli O157:H7 isolates; Taylor DE et al.; Strains of Escherichia coli causing enterohemorrhagic colitis belonging to the O157:H7 lineage are reported to be highly related . Fifteen strains of E . coli O157:H7 and 1 strain of E . coli O46:H(-) (nonflagellated) were examined for the presence of potassium tellurite resistance (Te(r)) . Te(r) genes comprising terABCDEF were shown previously to be part of a pathogenicity island also containing integrase, phage, and urease genes . PCR analysis, both conventional and light cycler based, demonstrated that about one-half of the Te(r) E . coli O157:H7 strains (6 of 15), including the Sakai strain, which has been sequenced, carried a single copy of the Te(r) genes . Five of the strains, including EDL933, which has also been sequenced, contained two copies . Three other O157:H7 strains and the O46:H(-) strain did not contain the Te(r) genes . In strains containing two copies, the Te(r) genes were associated with the serW and serX tRNA genes . Five O157:H7 strains resembled the O157 Sakai strain whose sequence contained one copy, close to serX, whereas in one isolate the single copy was associated with serW . There was no correlation between Te(r) and the ability to produce Shiga toxin ST1 or ST2 . The Te(r) MIC for most strains, containing either one or two copies, was 1,024 micro g/ml, although for a few the MIC was intermediate, 64 to 128 micro g/ml, which could be increased to 512 micro g/ml by pregrowth of strains in subinhibitory concentrations of potassium tellurite . Reverse transcriptase PCR analysis confirmed that in most strains Te(r) was constitutive but that in the rest it was inducible and involved induction of terB and terC genes . Only the terB, -C, -D, and -E genes are required for Te(r) . The considerable degree of homology between the ter genes on IncH12 plasmid R478, which originated in Serratia marcescens, and pTE53, from an E . coli clinical isolate, suggests that the pathogenicity island was acquired from a plasmid . This work demonstrates diversity among E . coli O157:H7 isolates, at least as far as the presence of Te(r) genes is concerned.

CLAO J, 2002 Jul, 28(3), 157 - 9
Association of Pseudomonas aeruginosa and Serratia marcescens with extended-wear soft contact lenses in asymptomatic patients; Ahanotu EN et al.; PURPOSE: To isolate and identify aerobic bacteria, particularly gram-negative species associated with the use of extended-wear (EW) soft contact lenses . METHODS: Extended-wear contact lenses were collected, using aseptic technique, from the eyes of individuals after 30 days of extended wear (5-7 day intermittent periods) and were examined for adhered aerobic bacteria . RESULT: Coagulase-negative staphylococci (CoNS) were isolated from 74% of the lenses . Serratia marcescens was found at an incidence of 10% and Pseudomonas aeruginosa at an incidence of 6% . CONCLUSION: The presence of species of bacteria, including P . aeruginosa and S . marcescens, that have been associated with daily wear soft contact lenses, solutions, and cases also appear to be associated with EW lenses.

J Biomed Mater Res, 2002 Sep 15, 61(4), 641 - 52
Adsorbed poly(ethyleneoxide)-poly(propyleneoxide) copolymers on synthetic surfaces: spectroscopy and microscopy of polymer structures and effects on adhesion of skin-borne bacteria; Marsh LH et al.; Poly(ethyleneoxide)-copoly(propyleneoxide) (PEO-PPO) polymer coatings were evaluated for their resistance to the attachment of the marker organism Serratia marcescens and the skin-borne bacteria Staphylococcus epidermidis . The copolymers were adsorbed onto poly(styrene) films-chosen as simplified physicochemical models of skin surfaces-and their surface characteristics probed by contact angle goniometry, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) . These functional surfaces were then presented to microbial cultures, bacterial attachment was assessed by fluorescence microscopy and AFM, and the structures of the polymer films examined again spectroscopically . Surface characterization data suggest that the adsorbed copolymer was partially retained at the surface and resisted bacterial attachment for 24 h . Quantitative evaluation of cell attachment was carried out by scintillation counting of (14)C-labeled microorganisms in conjunction with plate counts . The results show that a densely packed layer of PEO-PPO copolymer can reduce attachment of skin commensals by an order of magnitude, even when the coating is applied by a simple adsorptive process . The work supports the hypothesis that adhesion of microorganisms to biological substrates can be reduced if a pretreatment with an appropriate copolymer can be effected in vivo .

Environ Monit Assess, 2002 Jun, 76(2), 195 - 211
Time dependent influx and efflux of phenol by immobilized microbial consortium; Sharma A et al.; Phenol, like many other organic solvents, is toxic to micro-organisms even at low concentrations . However, some micro-organisms can withstand this toxicity to a certain concentration . To observe the uptake mechanism of phenol, bacteria were isolated from a petroleum refinery effluent and identified . Study was carried out to understand the effect of varying sub-lethal concentrations of phenol, on all the isolated individual bacterial cultures . Out of the bacteria isolated, Serratia liquefaciens was found to tolerate phenol concentration up to 1500 mg l(-1) . A microbial consortium of the isolated bacteria was formulated and immobilized . Individual cultures were also immobilized and uptake of phenol by the immobilized micro-organisms was observed in a nutrient-rich and nutrient-stressed medium containing phenol as a sole source of carbon . A time-dependent uptake of phenol was exhibited by the micro-organisms in nutrient-stressed medium, after which a sudden increase in phenol concentration occurred in the extracellular medium, till it reached back to the initial concentration . This was attributed to an active efflux mechanism adopted by the micro-organisms to withstand the toxic shock.

Bull Math Biol, 2002 May, 64(3), 565 - 87
Quantitative effects of medium hardness and nutrient availability on the swarming motility of Serratia liquefaciens; Bees MA et al.; We report the first controlled measurements of expansion rates for swarming colonies of Serratia liquefaciens under different growth conditions, combined with qualitative observations of the organization of the colony into regions of differentiated cell types . Significantly, the results reveal that swarming colonies of S . liquefaciens can have an increasing expansion rate with time . We compare and contrast the expansion rate results with predictions from a recent mathematical model which coupled key hydrodynamical and biological mechanisms . Furthermore, we investigate whether the swarming colonies grow according to a power law or exponentially (for large times), as suggested by recent theoretical results.

Biosci Biotechnol Biochem, 2002 May, 66(5), 1075 - 83
Chitinases A, B, and C1 of Serratia marcescens 2170 produced by recombinant Escherichia coli: enzymatic properties and synergism on chitin degradation; Suzuki K et al.; To discover the individual roles of the chitinases from Serratia marcescens 2170, chitinases A, B, and C1 (ChiA, ChiB, and ChiC1) were produced by Escherichia coli and their enzymatic properties as well as synergistic effect on chitin degradation were studied . All three chitinases showed a broad pH optimum and maintained significant chitinolytic activity between pH 4 and 10 . ChiA was the most active enzyme toward insoluble chitins, but ChiC1 was the most active toward soluble chitin derivatives among the three chitinases . Although all three chitinases released (GlcNAc)2 almost exclusively from colloidal chitin, ChiB and ChiC1 split (GlcNAc)6 to (GlcNAc)3, while ChiA exclusively generated (GlcNAc)2 and (GlcNAc)4 . Clear synergism on the hydrolysis of powdered chitin was observed in the combination between ChiA and either ChiB or ChiC, and the sites attacked by ChiA on the substrate are suggested to be different from those by either ChiB or ChiC1.

J Hosp Infect, 2002 Jun, 51(2), 96 - 105
A rapid and easy PCR-RFLP method for genotyping Serratia marcescens strains isolated in different hospital outbreaks and patient environments in the Lyon area, France; Parvaz P et al.; A new genotyping method for Serratia marcescens is described . This method uses the flagellin gene as target for polymerase chain reaction amplification and Alu I restriction fragment length polymorphism . The strains tested belonged to 13 different hospital clusters of S . marcescens isolated between 1983 and 1988, concerning outbreaks and/or patient environments in different hospital units in Lyon and the Rhone-Alpes region of France . Initially, the classification had been performed by marcescinotyping . These strains were then tested by ribotyping and genotyping of the flagellin gene . Genotyping showed similar classification to ribotyping . The genotyping method is the easiest technique, as reproducible as ribotyping, and with almost the same ability to discriminate different strains . It does not need expensive equipment, is more rapid, and is less labor intensive than ribotyping . With this method, all strains of S . marcescens including sporadic isolates could be amplified and typed . Antibiotic sensitivity determination was found to be a useful complementary and confirmation test for all these typing methods .

J Med Chem, 2002 Jul 4, 45(14), 3032 - 40
Highly antibacterial active aminoacyl penicillin conjugates with acylated bis-catecholate siderophores based on secondary diamino acids and related compounds; Heinisch L et al.; New acylated bis-catecholates and 1,3-benzoxazine-2,4-dione derivatives based on secondary diamino acids (N-(aminoalkyl)glycines, N-aminopropyl-alanine, and N-aminopropyl-4-aminovaleric acid), on N-(aminoalkyl)aminomethyl benzoic acids, on N-(aminoalkyl)aminomethyl phenoxyacetic acids, or on 3,5-diaminobenzoic acid were synthesized as artificial siderophores . The corresponding diamino acids were obtained from the diamines and oxocarboxylic acids by catalytic hydrogenation . The acylated bis-catecholates and 1,3-benzoxazine-2,4-diones were coupled with ampicillin or amoxicillin to new siderophore aminoacylpenicillin conjugates . These conjugates exhibited very strong antibacterial activity in vitro against Gram-negative bacterial pathogens including Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Escherichia coli, Klebsiella pneumoniae, and Serratia marcescens . The ampicillin derivative 7b (HKI 9924154) and the corresponding amoxicillin derivative 8 (HKI 9924155) represent the most active compounds . The conjugates can use bacterial iron siderophore uptake routes to penetrate the Gram-negative outer membrane permeability barrier . This was demonstrated by assays with mutants deficient in components of the iron transport systems . New siderophore penicillin V conjugates with the siderophore component attached to the phenyl ring of penicillin V are inactive against these Gram-negative bacteria.

J Dairy Sci, 2002 May, 85(5), 1111 - 8
Trends in antibacterial susceptibility of mastitis pathogens during a seven-year period; Erskine RJ et al.; Milk samples collected from dairy cattle suspected of having mastitis were submitted to the Microbiology Laboratory of the Animal Health Diagnostic Laboratory, Michigan State University, for bacteriologic culture . A total of 2778 isolates, from the years 1994 to 2000, were isolated, identified, and subjected to in vitro antimicrobial susceptibility testing using the disk diffusion method, in accordance with National Committee on Clinical Laboratory Standards (NCCLS) standards . Isolates included in this study were Streptococcus uberis, Streptococcus dysgalactiae, Streptococcus agalactiae, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Serratia marcesens, and Pseudomonas aeruginosa . The proportion of bacterial isolates determined to be susceptible did not change during the 7-yr period for the majority of bacterial-antibacterial interactions tested . However, analysis for linear trend in proportions determined that there were increases in the proportion of S . aureus isolates that were susceptible to ampicillin, penicillin, and erythromycin . For Strep . uberis, increases in the proportion of susceptible isolates occurred for oxacillin, sulfa-trimethoprim, gentamicin, and pirlimycin, and a decrease in the proportion of susceptible isolates occurred with penicillin . For Strep . dysgalactiae, increases in the proportion of susceptible isolates occurred with erythromycin, gentamicin, sulfa-trimethoprim, and tetracycline . For Strep . agalactiae, increases in the proportion of susceptible isolates occurred with sulfa-trimethoprim . Among E . coli isolates, there was an increase in the proportion that were susceptible to ampicillin and cephalothin . Among K pneumoniae isolates, there was an increase in the proportion that were susceptible to ceftiofur . Overall, there was no indication of increased resistance of mastitis isolates to antibacterials that are commonly used in dairy cattle.

J Bacteriol, 2002 Jul, 184(14), 3871 - 8
The PhlA hemolysin from the entomopathogenic bacterium Photorhabdus luminescens belongs to the two-partner secretion family of hemolysins; Brillard J et al.; Photorhabdus is an entomopathogenic bacterium symbiotically associated with nematodes of the family Heterorhabditidae . Bacterial hemolysins found in numerous pathogenic bacteria are often virulence factors . We describe here the nucleotide sequence and the molecular characterization of the Photorhabdus luminescens phlBA operon, a locus encoding a hemolysin which shows similarities to the Serratia type of hemolysins . It belongs to the two-partner secretion (TPS) family of proteins . In low-iron conditions, a transcriptional induction of the phlBA operon was observed by using the chloramphenicol acetyltransferase reporter gene, causing an increase in PhlA hemolytic activity compared to iron-rich media . A spontaneous phase variant of P . luminescens was deregulated in phlBA transcription . The phlA mutant constructed by allelic exchange remained highly pathogenic after injection in the lepidopteran Spodoptera littoralis, indicating that PhlA hemolysin is not a major virulence determinant . Using the gene encoding green fluorescent protein as a reporter, phlBA transcription was observed in hemolymph before insect death . We therefore discuss the possible role of PhlA hemolytic activity in the bacterium-nematode-insect interactions.

J Biol Inorg Chem, 2002 Jun, 7(6), 600 - 10 Epub 2002 Feb 15.
Mechanistic studies of the astacin-like Serratia metalloendopeptidase serralysin: highly active (>2000%) Co(II) and Cu(II) derivatives for further corroboration of a "metallotriad" mechanism; Park HI et al.; Serralysin is a bacterial Zn-endopeptidase which has been considered a virulence factor to cause tissue damage and anaphylactic response . It contains a coordinated Tyr that is unique to the astacin-like Zn enzymes . The coordinated Tyr has been proposed to play an important role in the action of this endopeptidase family . Several metal-substituted derivatives of serralysin (including Mn2+, Co2+, Ni2+, Cu2+, and Cd2+ derivatives) are found to exhibit significant activities . Particularly, the Co- and Cu-substituted derivatives exhibit much higher activities than the native serralysin toward the hydrolysis of the tripeptide mimic benzoyl-Arg- p-nitroanilide, i.e., 35 and 49 times higher in k(cat) and 33 and 26 times in k(cat)/ K(m), respectively . Such remarkably higher activities of metal-substituted derivatives, especially the Cu derivative, than that of the native Zn enzyme are rare in the literature, reflecting the uniqueness of this enzyme among all Zn enzymes . The significantly different k(cat) yet similar K(m) values among the several metal derivatives suggests that the metal center is involved in catalysis, but not necessarily in the binding of the substrate, whereas the dramatically different inhibition constants for Arg-hydroxamate binding to the metal-substituted derivatives indicates direct binding of this inhibitor to the metal center . The activity-pH profiles of serralysin and its Co2+ and Cu2+ derivatives and the optical-pH profile of Cu-serralysin have been obtained, in which the decrease in activity at higher pH values was found to be associated with a dramatic increase in the Tyr-to-Cu2+ charge transfer transitions . This observation suggests that the binding of Tyr216 to the metal is inhibitory . A metal-centered mechanism is proposed for serralysin catalysis based on the results presented here, in which the detachment of the coordinated Tyr and formation of a H-bond with the transition-state complex are considered essential for the stabilization of the transition state.

Prikl Biokhim Mikrobiol, 2002 May-Jun, 38(3), 248 - 56
{Extracellular chitinase production by wild-type B-10 and mutant M-1 strains of Serratia marcescens}; Duzhak AB et al.; Molecular weights of extracellular chitinases from wild-type B-10 (62, 54, 43, 38, and 21 kDa) and mutant M-1 strains of Serratia marcescens (62, 52, 43, 38, and 21 kDa) were estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis . In the absence of chitin inductors, chitinolytic enzymes were not found in the culture liquid of B-10, while M-10 cells produced the chitinase complex (to 470 pU/cell) . Crystalline chitin insignificantly stimulated the synthesis of chitinases with molecular weights of 62, 54, and 21 kDa by B-10 (up to 20 pU/cell), but caused overproduction of all chitinases by the mutant strain (up to 2600 pU/cell) . Colloidal chitin induced the production of chitinases by cells of both strains . Two peaks of chitinolytic activity were observed during cultivation of strains B-10 (350 and 450 pU/cell) and M-1 (2200 and 2400 pU/cell) . The first peak of cell productivity was associated with biosynthesis of the chitinase complex . The second peak was related to the production of enzymes with molecular weights of 54, 43, 38, and 21 kDa (B-10) or 43, 38, and 21 kDa (M-1).

Comp Biochem Physiol B Biochem Mol Biol, 2002 Jun, 132(2), 359 - 65
Antibacterial effect of a magnetic field on Serratia marcescens and related virulence to Hordeum vulgare and Rubus fruticosus callus cells; Piatti E et al.; The exposure to a static magnetic field of 80+/-20 Gauss (8+/-2 mT) resulted in the inhibition of Serratia marcescens growth . Callus cell suspensions from Hordeum vulgare and Rubus fruticosus were also examined and only the former was found to be affected by the magnetic field, which induced a decreased viability . S . marcescens was shown to be virulent only toward H . vulgare and this virulence was reduced by the presence of the magnetic field . The modification of glutathione peroxidase activity under the different experimental conditions allowed us to speculate on the possibility of an oxidative-stress response of H . vulgare both to S . marcescens infection and magnetic field exposure . Since the control of microbial growth by physical agents is of interest for agriculture, medicine and food sciences, the investigation presented herein could serve as a starting point for future studies on the efficacy of static magnetic field as low-cost/easy-handling preservative agent.

Kansenshogaku Zasshi, 2002 Apr, 76(4), 246 - 53
{IMP-1 type metalo-beta-lactamase producing Serratia marcescens strains isolated from blood culture between 1991 to 2000}; Nakamura T et al.; Infection caused by metallo beta-lactamase (MBL)-producing bacteria have been increasingly reported in Japan in recent years . We investigated the prevalence, clinical backgrounds and molecular epidemiology of MBL-producing Serratia marcescens strains isolated from blood cultures at our university hospital between 1991 and 2000 . Forty-three S . marcescens strains were isolated in the period, and the incidence reached about 2% total bacteria detection in 1998 and 1999 . There were 13 ceftazidime-resistant strains (31%), and five of them produced MBL . MICs of imipenem (IPM) were 4-16 mg/ml, of which one strain was susceptible to IPM . Of the five MBL-producers, four were obtained from a tertiary emergency ward, the underlying diseases being either serious trauma or cerebrovascular diseases . The other was isolated from a patient who underwent kidney transplantation . S . marcescens was no longer isolated from patients after administration of aztreonam (AZT), implying that AZT was clinically effective . When analyzed genetically using the AP-PCR technique, the patterns were identical among strains isolated in 1996, 1997 and 1998 and those isolated in 1999 and 2000 respectively, suggesting that the same strains may have inhabited the hospital wards for prolonged periods . Countermeasures against nosocomial infection was undertaken thereafter, resulting in reduction of isolation frequency . It cannot be excluded that the resistant bacteria spread as the amount of carbapenem consumption increased . Prudent use of antibiotics is mandatory to prevent further dissemination of such MBL producers.

Curr Pharm Biotechnol, 2002 Jun, 3(2), 117 - 27
Acquired carbapenem-hydrolyzing beta-lactamases and their genetic support; Poirel L et al.; Carbapenem-hydrolyzing beta-lactamases of several Ambler molecular classes have been reported as the source of acquired beta-lactam antibiotic resistance in Gram negative bacteria . The metallo-enzymes of Ambler class B are the most prevalent enzymes in this case . These clavulanic-acid resistant enzymes have a large spectrum of hydrolysis including penicillins, cephalosporins (third and fourth generations), carbapenems but not monobactams . They are responsible for acquired resistance in several Gram negative species of clinical relevance in human medicine . IMP-1 was the first reported as acquired in Japan, mostly from Serratia marcescens and Pseudomonas aeruginosa isolates, and has been detected in Europe recently . Several variants of IMP-1 (IMP-2 to -9) have been characterized, possessing 85 to 99% amino acid identity, mostly from P . aeruginosa isolates . In addition, VIM-1 to -3 beta-lactamases have also been described, first in Europe (Italy, France, and Greece) and now in Korea . The VIM series shares 30% amino acid identity with the IMP-series . Most of these class B enzymes have genes that are integron- and plasmid-located . Finally, a few Ambler class A (SME-1, NMC-A, IMI-1, KPC-1) and class D (OXA-23 to -27) beta-lactamases involved in carbapenem hydrolysis have been reported also from rare isolates of Gram-negative rods . This review underlines the worldwide spread of carbapenem-hydrolyzing beta-lactamases as representing an important threat for efficacy of antibiotics in the near future.

Antimicrob Agents Chemother, 2002 Jun, 46(6), 2041 - 5
Lentivirus lytic peptide 1 perturbs both outer and inner membranes of Serratia marcescens; Phadke SM et al.; Bis-lentivirus lytic protein 1 (Bis-LLP1) and polymyxin B exhibited similar killing activities against Serratia marcescens . By electron microscopy, bis-LLP1 interacted with the outer and cytoplasmic bacterial membranes, while polymyxin B affected only the outer membrane . The results of standard biochemical probes supported the findings of the electron microscopy studies, suggesting that these antimicrobial peptides have different mechanisms of action.

Appl Biochem Biotechnol, 2002 Spring, 98-100, 841 - 7
The influence of vegetable oils on biosurfactant production by Serratia marcescens; Ferraz C et al.; The production of biosurfactant, a surface-active compound, by two Serratia marcescensstrains was tested on minimal culture medium supplemented with vegetable oils, considering that it is well known that these compounds stimulate biosurfactant production . The vegetable oils tested included soybean, olive, castor, sunflower, and coconut fat . The results showed a decrease in surface tension of the culture medium without oil from 64.54 to 29.57, with a critical micelle dilution (CMD(-1)) and CMD(-2) of 41.77 and 68.92 mN/m, respectively . Sunflower oil gave the best results (29.75 mN/m) with a CMD(-1) and CMD-2 of 36.69 and 51.41 mN/m, respectively . Sunflower oil contains about 60% of linoleic acid . The addition of linoleic acid decreased the surface tension from 53.70 to 28.39, with a CMD(-1) of 29.72 and CMD(-2) of 37.97, suggesting that this fatty acid stimulates the biosurfactant production by the LB006 strain . In addition, the crude precipitate surfactant reduced the surface tension of water from 72.00 to 28.70 mN/m . These results suggest that the sunflower oil's linoleic acid was responsible for the increase in biosurfactant production by the LB006 strain.

Zhonghua Zhong Liu Za Zhi, 2002 Mar, 24(2), 188 - 90
{Serratia marcescens vaccine in the treatment of malignant pleural effusion}; Shi H et al.; OBJECTIVE: To evaluate the efficacy and toxicity of Serratia marcescens (S311) vaccine in the treatment of malignant pleural effusion . METHODS: Thirty-four patients with malignant pleural effusion were given S311 as intrapleural injection with a dose of 10(9) U (0.32 mg) on D 1, 8 and 15, and observed for four weeks . RESULTS: The overall response rate (CR + PR) was 97.1% (CR in 12 patients and PR in 21 patients) . The systemic toxicity was mild, including fever (82.4%), pleuritic pain (50.7%), nansea (26.5%), dyspnea (17.5%) and chills (5.9%) . CONCLUSION: Serratia marcescens vaccine is effective for malignant pleural effusion, with tolerable toxic effects . Further study is warranted.

Dermatology, 2002, 204 Suppl 1, 28 - 31
Strategy of control of nosocomial infections: application of disinfectants such as povidone-iodine; Kawana R et al.; At Morioka Yuai Hospital, the Infection Control Division was set up 5 years ago, and it has made efforts to actively control infections . In particular, the division succeeded in increasing the frequency of general round table discussions for patients with infections . We strongly recommend to frequently gargle with Isodine at operations . Recently, we have followed up patients with infections caused by MRSA, Pseudomonas aeruginosa and Serratia or carriers of these bacteria, and determined the drug sensitivities of clinical isolates . In addition, because of the current highly aged society, a high percentage of inpatients has various underlying diseases . In particular, there are quite a few cases in which pneumonia occurs as an opportunistic infection . From studies in these patients and patients of the dental department, it has been shown that oral microorganisms clearly decrease in count by careful tooth brushing and gargling with Isodine, with prevention of pneumonitis caused by oral microorganisms . As we consider that antisepsis with povidone-iodine is useful for the prevention of nosocomial and opportunistic infections, we would like to report the findings of our study currently under way .

Appl Environ Microbiol, 2002 May, 68(5), 2542 - 9
Rapid immunoassays for detection of UV-induced cyclobutane pyrimidine dimers in whole bacterial cells; Peccia J et al.; Immunoassays were developed to measure DNA damage retained by UV-irradiated whole bacterial cells . Active Mycobacterium parafortuitum and Serratia marcescens cells were fixed and incubated with cyclobutane pyrimidine dimer-binding antibodies after being exposed to known UV doses (254 nm) . When both fluorescent (Alexa Fluor 488) and radiolabeled ((125)I) secondary antibodies were used as reporters, indirect whole-cell assays were sensitive enough to measure intracellular UV photoproducts in M . parafortuitum and S . marcescens cells as well as photoenzymatic repair responses in S . marcescens cells . For the same UV dose, fluorescent DNA photoproduct detection limits in whole-cell assays (immunofluorescent microscopy) were similar to those in fluorescent assays performed on membrane-bound DNA extracts (immunoslot blot) . With either fluorescent or radiolabeled reporters, the intracellular cyclobutane pyrimidine dimer content of UV-irradiated whole bacterial cells could be reliably quantified after undergoing a <0.5-order-of-magnitude decrease in culturability . Immunofluorescent microscopy results showed that photoenzymatic repair competence is not uniformly distributed among exponential-growth UV-irradiated pure cultures.

Eur J Med Chem, 2002 Apr, 37(4), 323 - 32
Synthesis and antibacterial activity of dual-action agents of a beta-lactam antibiotic with cytotoxic agent mitozolomide or temozolomide; Wang Y et al.; Dual-action agents 5a-f and 12a-f, a beta-lactam antibiotic combined with a cytotoxic agent, mitozolomide (Meto) or temozolomide (Temo), were synthesised . The antibacterial activity (MICs) of the dual-action agents has been determined against a panel of bacteria including several beta-lactamase producing strains . The tests showed 5a-f active against the non-beta-lactamase producing methicillin sensitive Staphylococcus aureus (MSSA) strains, however, little synergistic effect between the beta-lactam and the cytotoxic agent was observed . 12a-f demonstrated some synergistic effect against bacteria . 12a, in particular, is active against ampicillin resistant (beta-lactamase-producing) strains of Serratia marcescens.

Bioorg Med Chem, 2002 Jun, 10(6), 1659 - 70
New synthetic siderophores and their beta-lactam conjugates based on diamino acids and dipeptides; Wittmann S et al.; Linking of siderophores to antibiotics improves the penetration and therefore increases the antibacterial activity of the antibiotics . We synthesized the acylated catecholates and hydroxamates as siderophore components for antibiotic conjugates to reduce side effects of unprotected catecholate and hydroxamate moieties . In this paper, we report on bis- and tris-catecholates and mixed catecholate hydroxamates based on diamino acids or dipeptides . These compounds were active as siderophores in a growth promotion assay under iron limitation . Most of the conjugates with beta-lactams showed high in vitro activity against Gram-negative bacteria especially Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens and Stenotrophomonas maltophilia . The compounds with enhanced antibacterial activity use active iron uptake routes to penetrate the bacterial outer membrane barrier, demonstrated by assays with mutants deficient in components of the iron transport system . Correlation between chemical structure and biological activity was studied.

Appl Microbiol Biotechnol, 2002 Mar, 58(3), 322 - 9 Epub 2001 Dec 08.
Utilization of ATP-binding cassette exporter for hyperproduction of an exoprotein: construction of lipase-hyperproducing recombinant strains of Serratia marcescens; Idei A et al.; The Serratia marcescens extracellular lipase (LipA) is an enzyme applicable to enantioselective hydrolysis of racemic substrates . The enzyme is secreted through an ATP-binding cassette (ABC) exporter, the Lip system, encoded by the lipBCD genes . The S . marcescens recombinant carrying pLIPE121, which encodes the lipA gene in pUC19, exhibited a higher LipA production level than the wild-type strain . However, the level was lower than expected, and secretion was suggested to be a bottleneck . lipBCD plasmids were introduced into S . marcescens recombinants harboring lipA plasmids and the effectiveness of the lipBCD plasmids in elevating LipA productivity was investigated . S . marcescens strains harboring both lipA and lipBCD plasmids showed sevenfold greater extracellular LipA activity than the strain harboring the lipA plasmid alone . A high level of extracellular LipA production (1,300 kU/ml) and high plasmid stability (enough to carry out large-scale cultivation) were observed under non-selective conditions . Addition of L-proline and Tween 80 was effective in increasing cell growth of the recombinant, which led to high LipA production . In batch cultivation using a 30-l jar fermentor, LipA production was achieved at a high level of 5,200 kU/ml . This is the first report describing utilization of ABC exporter for the overproduction of an industrially important extracellular protein.

J Med Entomol, 2002 Jan, 39(1), 89 - 98
Comparsion of selected growth media for culturing Serratia marcescens, Aeromonas sp., and Pseudomonas aeruginosa as pathogens of adult Stomoxys calcitrans (Diptera: Muscidae); Lysyk TJ et al.; Stable flies, Stomoxys calcitrans (L.), were orally infected with Aeromonas sp., Pseudomonas aeruginosa (Schroeter), and Serratia marcescens Bizio that were cultured on egg-yolk media, nutrient broth, and fly egg media . Aeromonas and Serratia caused mortality when the bacteria were originally grown on egg-yolk medium . Pseudomonas was equally lethal regardless of the media on which it was cultured . A wild isolate of Aeromonas caused greater death than an isolate that had been passed through host flies and had been reisolated from killed flies . Mortality increased with bacterial dose for all species . Aeromonas and Serratia caused mortality within several days after ingestion, whereas Pseudomonas caused a gradual increase in mortality 3-7 d after ingestion . The pathologic activity of Aeromonas and Serratia required extracellular products produced when cells were grown in egg yolk medium . Aeromonas required both supernatant and cells from egg yolk medium, wereas Serratia required supernatant from egg yolk medium and cells from either nutrient broth or egg yolk medium . Mortality due to ingestion of Aeromonas was correlated with the presence of enzymes that cause alpha- and beta-hemolysis, while mortality following ingestion of Serratia was associated with alpha-hemolysins, elastases, and chitinases.

J Clin Microbiol, 2002 Apr, 40(4), 1563 - 4
Serratia ficaria endophthalmitis; Badenoch PR et al.; We report a case of Serratia ficaria endophthalmitis in a 73-year-old man . The patient's ocular history included a chemical burn, glaucoma, and corneal transplantation . S . ficaria is part of the fig tree ecosystem and is rarely isolated from clinical specimens . When it has been previously implicated as an agent of disease, the patients have been treated successfully and there have been no complications . In our patient, however, the infection resulted in the loss of the infected eye . This case illustrates that S . ficaria infection in a compromised patient can have serious consequences.

Protein Sci, 2002 Apr, 11(4), 757 - 65
Histidine pK(a) shifts and changes of tautomeric states induced by the binding of gallium-protoporphyrin IX in the hemophore HasA(SM); Wolff N et al.; The HasA(SM) hemophore, secreted by Serratia marcescens, binds free or hemoprotein bound heme with high affinity and delivers it to a specific outer membrane receptor, HasR . In HasA(SM), heme is held by two loops and coordinated to iron by two residues, His 32 and Tyr 75 . A third residue His 83 was shown recently to play a crucial role in heme ligation . To address the mechanistic issues of the heme capture and release processes, the histidine protonation states were studied in both apo- and holo-forms of HasA(SM) in solution . Holo-HasA(SM) was formed with gallium-protoporphyrin IX (GaPPIX), giving rise to a diamagnetic protein . By use of heteronuclear correlation NMR spectroscopy, the imidazole side-chain (15)N and (1)H resonances of the six HasA(SM) histidines were assigned and their pKa values and predominant tautomeric states according to pH were determined . We show that protonation states of the heme pocket histidines can modulate the nucleophilic character of the two axial ligands and, consequently, control the heme binding . In particular, the essential role of the His 83 is emphasized according to its direct interaction with Tyr 75.

Kansenshogaku Zasshi, 2002 Feb, 76(2), 109 - 12
{Community acquired sepsis by Serratia rubidaea}; Okada T et al.; A 48-year-old male who had a past history of alcoholic pancreatitis and diabetes mellitus was admitted to our hospital due to chills and vomiting, on August 13, 1998 . His body temperature was 38.0 degrees C, and he had the disturbance of consciousness, tachypnea, tachycardia and hepatomegaly with tenderness . Laboratory findings showed highly inflammatory reactions, DIC and hepatorenal dysfunction . Abdominal CT and US revealed multiple liver abscess with portal vein thrombus . Serratia rubidaea was detected in the blood culture . SBT/CPZ and TOB were administered and he recovered . This is a rare case of Serratia rubidaea sepsis . It is also necessary to pay attention to Serratia infections as well as S . marcescens.

J Hosp Infect, 2002 Mar, 50(3), 170 - 4
Polymicrobial ventriculitis and evaluation of an outbreak in a surgical intensive care unit due to inadequate sterilization; Esel D et al.; At the end of 1999, a case of polymicrobial ventriculitis in the Department of Neurosurgery followed by an outbreak of Serratia marcescens mediastinitis in the intensive care unit of cardiovascular surgery occurred . These nosocomial surgical infections were considered to be the result of contamination of surgical sites with inadequately sterilized instruments or theatre linen . An epidemiological survey was focused on the central sterilization unit of the hospital . The microbiological results of this survey proved that the cause of the outbreak was the use of inadequately decontaminated theatre linen . This study indicates that strict infection control measures including the control of sterilization procedures and a well-organized infection control team are necessary to prevent nosocomial surgical infections .

Toxicol Lett, 2002 Mar 24, 129(1-2), 93 - 8
The cytotoxic prodigiosin induces phosphorylation of p38-MAPK but not of SAPK/JNK; Montaner B et al.; Prodigiosin (PG) is a red pigment produced by Serratia marcescens, with cytotoxic and immunosuppressive activity . It induces apoptosis in several cancer cell lines, including Jurkat-T cells . Here we examine the role of two stress-stimulated kinase cascades in this induction . Time course experiments using polyclonal antibodies showed that p38-MAPK phosphorylation began at 15 min and lasted for 3 h, whereas JNK was not phosphorylated, although both proteins were present . SB203580, a selective inhibitor of p38-MAPK, blocked its phosphorylation in PG-treated cells . Taken together, these data suggest that the PG induces phosphorylation of p38-MAPK but not of SAPK/JNK and that it increases the expression of both c-jun and c-fos oncoproteins.

Jpn J Antibiot, 2001 Dec, 54(12), 581 - 95
{Bactericidal activity of biapenem against various bacteria}; Hiraishi T et al.; The bactericidal activity of biapenem (BIPM), a new carbapenem agent, against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Serratia marcescens was compared with those of imipenem (IPM), panipenem (PAPM), meropenem (MEPM) and ceftazidime (CAZ) . The bactericidal activity of BIPM against S . aureus was equal to those of IPM, PAPM and MEPM . Against E . coli and K . pneumoniae, BIPM showed higher bactericidal activity than IPM and PAPM . Against P . aeruginosa, BIPM showed excellent bactericidal activity campared with IPM . The killing speeds of BIPM and IPM were obviously the most rapid among four carbapenems . BIPM showed a strong bactericidal activity against 5 species of bacteria including P . aeruginosa.

Bioorg Khim, 2002 Jan-Feb, 28(1), 23 - 31
{A comparative structure-function analysis and molecular mechanism of action of endonucleases from Serratia marcescens and Physarum polycephalum}; Shliapnikov SV et al.; Structural and functional characteristics were compared for wild-type nuclease from Serratia marcescens, which belongs to the family of DNA/RNA nonspecific endonucleases, its mutational forms, and the nuclease I-PpoI from Physarum polycephalum, which is a representative of the Cys-His box-containing subgroup of the superfamily of extremely specific intron-encoded homing DNases . Despite the lack of sequence homology and the overall different topology of the Serratia marcescens and I-PpoI nucleases, their active sites have a remarkable structural similarity . Both of them have a unique magnesium atom in the active site, which is a part of the coordinatively bonded water-magnesium complex involved in their catalytic acts . In the enzyme-substrate complexes, the Mg2+ ion is chelated by an Asp residue, coordinates two oxygen atoms of DNA, and stabilizes the transition state of the phosphate anion and 3'-OH group of the leaving nucleotide . A new mechanism of the phosphodiester bond cleavage, which is common for the Serratia marcescens and I-PpoI nucleases and differs from the known functioning mechanism of the restriction and homing endonucleases, was proposed . It presumes a His residue as a general base for the activation of a non-cluster water molecule at the nucleophilic in line displacement of the 3'-leaving group . A strained metalloenzyme-substrate complex is formed during hydrolysis and relaxes to the initial state after the reaction . The English version of the paper.

Clin Microbiol Infect, 1999 May, 5(5), 270 - 276
RAPD typing of Klebsiella pneumoniae, Klebsiella oxytoca, Serratia marcescens and Pseudomonas aeruginosa isolates using standardized reagents; Vogel L et al.; OBJECTIVE: To perform quality assessment of standardized random amplified polymorphic DNA (RAPD) analysis for epidemiologic typing of Klebsiella pneumoniae, K . oxytoca, Serratia marcescens and Pseudomonas aeruginosa . METHODS: Thirty K . pneumoniae, 15 K . oxytoca, 30 S . marcescens and 33 P . aeruginosa epidemiologically unrelated isolates and four collections of clinically related isolates of each species were included in the study . RAPD analysis was performed using Ready-To-Go RAPD Analysis beads with primer ERIC-1R and Ready-To-Go primer 2 for K . pneumoniae and K . oxytoca, primer set ERIC-2/1026 and Ready-To-Go primer 2 for S . marcescens, and primers D-10514 and D-14306 for P . aeruginosa . RESULTS: All epidemiologically unrelated K . pneumoniae and K . oxytoca isolates were distinguished . Twenty-nine types were distinguished among the 30 unrelated S . marcescens isolates and 32 types among the 33 unrelated P . aeruginosa isolates . Indistinguishable banding patterns were obtained in repeated analyses of two isolates and from 11 serial subcultures of three isolates of each species included in the study . The RAPD data from the clinically related isolates correlated with the epidemiologic origin of the isolates . CONCLUSIONS: The use of Ready-To-Go RAPD Analysis beads resulted in reproducible and stable banding patterns with a high discriminatory capacity, and the RAPD typing results corresponded with the epidemiologic origin of the isolates.

Infect Immun, 2002 Mar, 70(3), 1121 - 8
Characterization of a cytotoxic factor in culture filtrates of Serratia marcescens; Marty KB et al.; Serratia marcescens culture filtrates have been reported to be cytotoxic to mammalian cells . Using biochemical and genetic approaches, we have identified a major source of this cytotoxic activity . Both heat and protease treatments abrogated the cytotoxicity of S . marcescens culture filtrates towards HeLa cells, suggesting the involvement of one or more protein factors . A screen for in vitro cytotoxic activity revealed that S . marcescens mutant strains that are deficient in production of a 56-kDa metalloprotease are significantly less cytotoxic to mammalian cells . Cytotoxicity was significantly reduced when culture filtrates prepared from wild-type strains were pretreated with either EDTA or 1,10-phenanthroline, which are potent inhibitors of the 56-kDa metalloprotease . Furthermore, cytotoxic activity was restored when the same culture filtrates were incubated with zinc divalent cations, which are essential for enzymatic activity of the 56-kDa metalloprotease . Finally, recombinant expression of the S . marcescens 56-kDa metalloprotease conferred a cytotoxic phenotype on the culture filtrates of a nonpathogenic Escherichia coli strain . Collectively, these data suggest that the 56-kDa metalloprotease contributes significantly to the in vitro cytotoxic activity commonly observed in S . marcescens culture filtrates.

Biochem Pharmacol, 2002 Feb 1, 63(3), 463 - 9
Activation of protein kinase C for protection of cells against apoptosis induced by the immunosuppressor prodigiosin; Ramoneda BM et al.; Prodigiosin (PG) is a red pigment produced by Serratia marcescens with immunosuppressive activity . We had recently shown that PG-induced apoptosis in several cancer cell lines including Jurkat-T cells, while acting rapidly, potently and with no marked toxicity in non-malignant cells . Here we examine the role of protein kinase C (PKC) in the regulation of apoptosis triggered by PG . We evaluated the use of phorbol-myristate acetate (PMA) in the inhibition of apoptosis induced by PG in Jurkat-T cells by using FACS analysis of the phosphatidylserine externalisation, Hoechst 33342 staining and fragmentation pattern of DNA as well as proteolysis of poly-(ADP) ribose polymerase (PARP) . The anti-apoptotic effect of PMA was accompanied by phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) . Pretreatment of cells with MEK inhibitor PD98059 inhibited PMA-induced phosphorylation of ERK1/2 and the cytoprotective ability of PMA . These results suggest that activation of PKC in Jurkat-T cells confer protection against apoptosis induced by PG and that ERK1/2 mediate anti-apoptotic PKC signaling.

Bioorg Med Chem, 2002 Apr, 10(4), 1123 - 8
Psammaplin A, a chitinase inhibitor isolated from the Fijian marine sponge Aplysinella rhax; Tabudravu JN et al.; Several brominated tyrosine derived compounds, psammaplins A (1), K (2) and L (3) as well as bisaprasin (4) were isolated from the Fijian marine sponge Aplysinella rhax during a bioassay guided isolation protocol . Their structures were determined using NMR and MS techniques . Psammaplin A was found to moderately inhibit chitinase B from Serratia marcescens, the mode of inhibition being non-competitive . Crystallographic studies suggest that a disordered psammaplin A molecule is bound near the active site . Interestingly, psammaplin A was found to be a potent antifungal agent.

Clin Infect Dis, 2002 Mar 15, 34(6), 767 - 73 Epub 2002 Feb 05.
Three consecutive outbreaks of Serratia marcescens in a neonatal intensive care unit; Fleisch F et al.; We investigated an outbreak of Serratia marcescens in the neonatal intensive care unit (NICU) of the University Hospital of Zurich . S . marcescens infection was detected in 4 children transferred from the NICU to the University Children's Hospital (Zurich) . All isolates showed identical banding patterns by pulsed-field gel electrophoresis (PFGE) . In a prevalence survey, 11 of 20 neonates were found to be colonized . S . marcescens was isolated from bottles of liquid theophylline . Despite replacement of these bottles, S . marcescens colonization was detected in additional patients . Prospective collection of stool and gastric aspirate specimens revealed that colonization occurred in some babies within 24 hours after delivery . These isolates showed a different genotype . Cultures of milk from used milk bottles yielded S . marcescens . These isolates showed a third genotype . The method of reprocessing bottles was changed to thermal disinfection . In follow-up prevalence studies, 0 of 29 neonates were found to be colonized by S . marcescens . In summary, 3 consecutive outbreaks caused by 3 genetically unrelated clones of S . marcescens could be documented . Contaminated milk could be identified as the source of at least the third outbreak.

J Biol Chem, 2002 Apr 12, 277(15), 13229 - 36 Epub 2002 Jan 30.
Crystal structure of imaginal disc growth factor-2 . A member of a new family of growth-promoting glycoproteins from Drosophila melanogaster; Varela PF et al.; Imaginal disc growth factor-2 (IDGF-2) is a member of a recently described family of Drosophila melanogaster-soluble polypeptide growth factors that promote cell proliferation in imaginal discs . Although their precise mode of action has not been established, IDGFs cooperate with insulin in stimulating the growth of imaginal disc cells . We report the crystal structure of IDGF-2 at 1.3-A resolution . The structure shows the classical (betaalpha)(8) barrel-fold of family 18 glycosyl hydrolases, with an insertion of an alpha + beta domain similar to that of Serratia marcescens chitinases A and B . However, amino acid substitutions in the consensus catalytic sequence of chitinases give IDGF-2 a less negatively charged environment in its putative ligand-binding site and preclude the nucleophilic attack mechanism of chitin hydrolysis . Particularly important is the replacement of Glu by Gln at position 132, which has been shown to abolish enzymatic activity in chitinases . Nevertheless, a modest conservation of residues that participate in oligosaccharide recognition suggests that IDGF-2 could bind carbohydrates, assuming several conformational changes to open the partially occluded binding site . Thus, IDGFs may have evolved from chitinases to acquire new functions as growth factors, interacting with cell surface glycoproteins implicated in growth-promoting processes, such as the Drosophila insulin receptor.

Bioorg Khim, 2001 Nov-Dec, 27(6), 417 - 25
{X-ray structural analysis of magnesium-containing Serratia marcescens endonuclease}; Shliapnikov SV et al.; The three-dimensional crystal structure of the DNA/RNA nonspecific endonuclease from Serratia marcescens was refined at the resolution of 1.07 A to R factor of 12.4% and Rfree factor of 15.3% using the anisotropic approximation . The structure includes 3924 non-hydrogen atoms, 715 protein-bound water molecules, and a Mg2+ ion in each binding site of each subunit of the nuclease homodimeric globular molecule . The 3D topological model of the enzyme was revealed, the inner symmetry of the monomers in its N- and C-termini was found, and the local environment of the magnesium cofactor in the nuclease active site was defined . Mg2+ ion was found to be bound to the Asn119 residue and surrounded by five associated water molecules that form an octahedral configuration . The coordination distances for the water molecules and the O delta 1 atom of Asn119 were shown to be within a range of 2.01-2.11 A . The thermal factors for the magnesium ion in subunits are 7.08 and 4.60 A2, and the average thermal factors for the surrounding water molecules are 11.14 and 10.30 A2, respectively . The region of the nuclease subunit interactions was localized, and the alternative side chain conformations were defined for 51 amino acid residues of the nuclease dimer.

J Infect Chemother, 1999 Mar, 5(1), 49 - 51
A plasmid-mediated beta-lactamase with carbapenem-hydrolyzing activity from Serratia marcescens; Matsumura N et al.; Serratia marcescens W-313/pSW313 was isolated from a clinical specimen that showed resistance to various beta-lactams . beta-Lactamase from this strain hydrolyzed oxyiminocephalosporins and carbapenems, but did not hydrolyze 2-carboxypenam and aztreonam . The kinetic parameters of this enzyme were similar to those of the carbapenem-hydrolyzing beta-lactamases mediated by R-plasmid from Pseudomonas aeruginosa and S . marcescens, whose properties were previously reported.

Acta Crystallogr D Biol Crystallogr, 2002 Feb, 58(Pt 2), 377 - 9 Epub 2002 Jan 24.
Structure of the D140N mutant of chitinase B from Serratia marcescens at 1.45 A resolution; Kolstad G et al.; The crystal structure of the inactive D140N mutant of Serratia marcescens was refined to 1.45 A resolution . The structure of the mutant was essentially identical to that of the wild type, with the exception of a rotation of Asp142 in the catalytic centre . In the mutant, this residue interacts with the catalytic acid (Glu144) and not with residue 140 as in the wild type . Thus, the 500-fold decrease in activity in the D140N mutant seems to be largely mediated by an effect on Asp142, confirming the crucial role of the latter residue in catalysis.

Acta Crystallogr D Biol Crystallogr, 2002 Feb, 58(Pt 2), 267 - 74 Epub 2002 Jan 24.
Structure of the imipenem-hydrolyzing class A beta-lactamase SME-1 from Serratia marcescens; Sougakoff W et al.; The structure of the beta-lactamase SME-1 from Serratia marcescens, a class A enzyme characterized by its significant activity against imipenem, has been determined to 2.13 A resolution . The overall structure of SME-1 is similar to that of other class A beta-lactamases . In the active-site cavity, most of the residues found in SME-1 are conserved among class A beta-lactamases, except at positions 104, 105 and 237, where a tyrosine, a histidine and a serine are found, respectively, and at position 238, which is occupied by a cysteine forming a disulfide bridge with the other cysteine residue located at position 69 . The crucial role played by this disulfide bridge in SME-1 was confirmed by site-directed mutagenesis of Cys69 to Ala, which resulted in a mutant unable to confer resistance to imipenem and all other beta-lactam antibiotics tested . Another striking structural feature found in SME-1 was the short distance separating the side chains of the active serine residue at position 70 and the strictly conserved glutamate at position 166, which is up to 1.4 A shorter in SME-1 compared with other class A beta-lactamases . Consequently, the SME-1 structure cannot accommodate the essential catalytic water molecule found between Ser70 and Glu166 in the other class A beta-lactamases described so far, suggesting that a significant conformational change may be necessary in SME-1 to properly position the hydrolytic water molecule involved in the hydrolysis of the acyl-enzyme intermediate.

J Cardiovasc Surg (Torino), 2002 Feb, 43(1), 91 - 3
Thrombectomy and SVC reconstruction due to infective thrombus; Uwabe K et al.; We report a case of thrombectomy and reconstruction of superior vena cava (SVC) in a patient presenting sepsis and SVC syndrome by infective thrombus . A 58-year-old woman presented sepsis and edema of the neck and left upper extremity during treatment of multiple organ failure . Sepsis by Serratia persisted in spite of appropriate antibiotic treatment . Computed tomography of the chest revealed thrombi that narrowed the SVC with obstruction of the left brachiocephalic vein . Removal of the infective thrombi followed by SVC reconstruction with autologous pericardial patch was performed . Postoperative period remained uneventful.

Biol Sci Space . 2001 Oct;15 Suppl:S190.
Microflora investigation experiment; Harada K; Many microorganisms were isolated from condensed water, wiping and scratching of cabin wall and air sampler in Russian space station Mir by Russian astronauts Lazutkin et al . in February 1997 as part of NASDA "First MIR Utilization Space Experiment (JMIR)" . For example, there were about 2 x 10(6) cells/ml in condensed water sample No . 1 isolated from the transfer-docking compartment of Crystal module . We tried the colony isolation, pure culturing and identification from these sampled microorganisms . After the bacteria separated from filamentous fungi and yeasts were observed using the phase contrast optical microscopy and gram stain method, twenty-one kinds of biochemical characters, e.g., oxidase test, activity of beta-galactosidase and fermentation of glucose etc., were investigated on the isolated bacteria . Then, we found Serratia liquefaciens and Yersinia enterocolitica and the chemoheterotroph Pseudomonadaceae, Stenotrophomonas maltophila . Furthermore, using ultraviolet (UV) lamp we tried the isolation of radioresistant bacteria, we found the radioresistant Sphingomonas paucimobilis (90.8% identification) by comparing with radioresistant Escherichia coli B/r strain . Considering Mir environment under cosmic radiation, this radioresistant S . paucimobilis might be the mutant from radiosensitive one . Following papers were published {see text}.

Environ Health Perspect, 2002 Jan, 110(1), 95 - 101
The characterization of upper-room ultraviolet germicidal irradiation in inactivating airborne microorganisms; Ko G et al.; In this study, we explored the efficacy of upper-room ultraviolet germicidal irradiation (UVGI) in reducing the concentration of Serratia marcescens and Mycobacterium bovis bacille Calmette-Guerin (BCG) aerosols in enclosed places . We constructed a facility (4.5 m x 3 m x 2.9 m) in which both ceiling- and wall-mounted UV fixtures (UV output: 10W and 5W respectively) were installed . The use of ceiling- and wall-mounted UV fixtures (total UV output: 15W) without mixing fan reduced the concentration of S . marcescens aerosols by 46% (range: 22-80%) at 2 air changes per hour (ACH) and 53% (range: 40-68%) at 6 ACH . The use of ceiling- and wall-mounted UV fixtures with mixing fan increased the UV effectiveness in inactivating S . marcescens aerosols to 62% (range: 50-78%) at 2 ACH and to 86% (81-89%) at 6 ACH . For BCG aerosols, UV effectiveness in inactivating BCG aerosols at 6 ACH were 52% (range: 11-69%) by ceiling-mounted UV fixture only (total UV output: 10W) and 64% (51-83%) by both ceiling- and wall-mounted UV fixtures (total UV output: 15W) . Our results indicated that the equivalent ventilation rate attributable to upper-room UVGI for BCG aerosols ranged from 1 ACH to 22 ACH for ceiling-mounted UV fixtures and from 6.4 ACH to 28.5 ACH for ceiling- and wall-mounted UV fixtures . Both generalized linear and generalized additive models were fitted to all our data . The regression results indicated that the number of UV fixtures, use of mixing fan, and air exchange rate significantly affected UV effectiveness (p < 0.01, 0.01, 0.01 respectively) . However, the strain difference (S . marcescens vs . BCG) appeared less important in UV effectiveness (p = 0.26) . Our results also indicated that UV effectiveness increased at higher temperature ((italic)p(/italic) < 0.01), lower dry-bulb temperature ((italic)p(/italic) = 0.21), and colder air from a supply grill located near the ceiling (p = 0.22).

Infect Control Hosp Epidemiol, 2001 Oct, 22(10), 630 - 4
Molecular epidemiology of an outbreak of Serratia marcescens in a neonatal intensive care unit; Villari P et al.; OBJECTIVE: To investigate and control a biphasic outbreak of Serratia marcescens in a neonatal intensive care unit (NICU) . DESIGN: Epidemiological and laboratory investigation of the outbreak . SETTING: The NICU of the 1,470-bed teaching hospital of the University "Federico II," Naples, Italy . PATIENTS: The outbreak involved 56 cases of colonization by S marcescens over a 15-month period, with two epidemic peaks of 6 and 3 months, respectively . Fourteen (25%) of the 56 colonized infants developed clinical infections, 50% of which were major (sepsis, meningitis, or pneumonia) . METHODS: Epidemiological and microbiological investigations, analysis of macrorestriction pattern of genomic DNA through pulsed-field gel electrophoresis (PFGE) of clinical and environmental isolates, and institution of infection control measures . RESULTS: Analysis of macrorestriction patterns of genomic DNA by PFGE demonstrated that the vast majority of S marcescens isolates, including three environmental strains isolated from two handwashing disinfectants and the hands of a nurse, were of the same clonal type . The successful control of the outbreak was achieved through cohorting of noncolonized infants, isolation of S marcescens-infected and -colonized infants, and an intense educational program that emphasized the need for adherence to glove use and handwashing policies . The NICU remained open to new admissions . CONCLUSIONS: Outbreaks caused by S marcescens are very difficult to eradicate . An infection control program that includes molecular typing of microorganisms and the proper dissemination among staff members of the typing results is likely to be very effective in reducing NICU-acquired infections and in controlling outbreaks caused by S marcescens, as well as other multiresistant bacteria.

Bull Soc Pathol Exot, 2000 Jan, 93(5), 307 - 10
{Value of antibiotype and bacteriocinotype for differentiating Shigella strains isolated in Argentina}; Merino LA et al.; The aim of the present work was to analyse the phenotypical characteristics of Shigella strains in order to evaluate their possible utilisation as epidemiological markers . For one year, we studied 95 strains of Shigella obtained from stool specimens of patients with dysentery . Bacteria came from various health care centres in the states of Chaco and Corrientes (Argentina) . Bacteria were identified by using classical biochemical methods . All strains were serotyped and susceptibility patterns were determined using thirteen antibiotics . Bacteriocin typing was determined by the sensitivity to piocins of Pseudomonas aeruginosa and to marcescins of Serratia marcescens . Colicin production in S . sonnei was also studied . Among all the strains examined, the most prevalent was Shigella flexneri (82%) followed by Shigella sonnei (18%) . The most frequent serotype among S . flexneri was 2 (93%), followed by serotypes 6 (4%), 1 (1.5%), and 3 (1.5%) . S . sonnei strains were classified in 7 antibiotypes, 6 piocin types, 3 marcescin types, and 4 colicin types . Strains of S . flexneri type 2 were divided among 14 antibiotypes, 4 piocin types and 2 marcescin types . Simpson's index of diversity was applied to evaluate the discriminatory power of studied typing methods, both alone and combined . Our results indicate that when taken independently, none of the evaluated typing methods had discriminative power, but when taken together, they may be successfully used for the epidemiological typing of Shigella strains.

FEMS Microbiol Lett, 2001 Dec 18, 205(2), 215 - 20
Cloning of a Serratia marcescens DNA fragment that induces quinoprotein glucose dehydrogenase-mediated gluconic acid production in Escherichia coli in the presence of stationary phase Serratia marcescens; Krishnaraj PU et al.; Serratia marcescens ER2 was isolated from an endorhizosphere sample based on its high level of mineral phosphate solubilizing (MPS) activity . This phenotype was correlated with expression of the direct oxidation pathway . An ER2 plasmid library constructed in Escherichia coli strain DH5alpha was screened for MPS activity . A recombinant clone DH5alpha (pKG3791) was capable of gluconic acid (GA) production and tricalcium phosphate solubilization but only in the presence of stationary phase ER2 cells . GA production in DH5alpha (pKG3791) was apparently the result of the quinoprotein glucose dehydrogenase activity because AG121 (a Tn5 knockout of gcd) carrying pKG3791 did not produce GA under the same conditions . GA production by DH5alpha (pKG3791) was not observed when ER2 was replaced by another PQQ-producing strain bacterium . These data add to a growing body of evidence that E . coli contains some type of PQQ biosynthesis pathway distinct from those previously characterized in Gram-negative bacteria and that these genes may be induced under appropriate conditions.

FEMS Microbiol Rev, 2001 Dec, 25(5), 583 - 613
Sugar non-specific endonucleases; Rangarajan ES et al.; Sugar non-specific endonucleases are multifunctional enzymes and are widespread in distribution . Apart from nutrition, they have also been implicated in cellular functions like replication, recombination and repair . Their ability to recognize different DNA structures has also been exploited for the determination of nucleic acid structure . Although more than 30 non-specific endonucleases have been isolated to date, very little information is available regarding their structure-function correlations except that of staphylococcal and Serratia nucleases . However, during the past few years, the primary structure, nature of the active site based on sequence homology, and the probable mechanism of action have been postulated for some of the enzymes . This review describes the purification, characteristics, biological role and applications of sugar non-specific endonucleases.

Surv Ophthalmol, 2001 Nov-Dec, 46(3), 259 - 68
Endogenous Serratia marcescens endophthalmitis with dark hypopyon: case report and review; Equi RA et al.; A case of endogenous Serratia marcescens endophthalmitis in a patient with diabetes, end-stage renal disease, and an indwelling venous catheter is reported . The patient presented with a tan hypopyon and elevated intraocular pressure . Diagnosis was established by positive blood, vitreous, conjunctival, and catheter tip cultures . After a deteriorating course the eye was enucleated . Gross and histopathologic examination revealed the presence of a dark hypopyon with iris necrosis and pigment dispersion and possible spontaneous globe perforation . This is the eleventh reported case of endogenous Serratia endophthalmitis . Previous association of a pink hypopyon and of pigmented vitreous fluid and Serratia endophthalmitis has been reported . This is the first case of dark hypopyon in endogenous Serratia marcescens endophthalmitis reported in the medical literature . Previous entities associated with dark hypopyon have been limited to intraocular melanoma and Listeria monocytogenes endophthalmitis . Dark hypopyon in the appropriate clinical setting may be useful in aiding diagnostic and therapeutic decisions.

Mol Microbiol, 2001 Nov, 42(4), 995 - 1005
Characterization of HasB, a Serratia marcescens TonB-like protein specifically involved in the haemophore-dependent haem acquisition system; Paquelin A et al.; In Gram-negative bacteria, the TonB-ExbB-ExbD inner membrane multiprotein complex is required for active transport of diverse molecules through the outer membrane . We present evidence that Serratia marcescens, like several other Gram-negative bacteria, has two TonB proteins: the previously characterized TonBSM, and also HasB, a newly identified component of the has operon that encodes a haemophore-dependent haem acquisition system . This system involves a soluble extracellular protein (the HasA haemophore) that acquires free or haemoprotein-bound haem and presents it to a specific outer membrane haemophore receptor (HasR) . TonBSM and HasB are significantly similar and can replace each other for haem acquisition . However, TonBSM, but not HasB, mediates iron acquisition from iron sources other than haem and haemoproteins, showing that HasB and TonBSM only display partial redundancy . The reconstitution in Escherichia coli of the S . marcescens Has system demonstrated that haem uptake is dependent on the E . coli ExbB, ExbD and TonB proteins and that HasB is non-functional in E . coli . Nevertheless, a mutation in the HasB transmembrane anchor domain allows it to replace TonBEC for haem acquisition . As the change affects a domain involved in specific TonBEC-ExbBEC interactions, HasB may be unable to interact with ExbBEC, and the HasB mutation may allow this interaction . In E . coli, the HasB mutant protein was functional for haem uptake but could not complement the other TonBEC-dependent functions, such as iron siderophore acquisition, and phage DNA and colicin uptake . Our findings support the emerging hypothesis that TonB homologues are widespread in bacteria, where they may have specific functions in receptor-ligand uptake systems.

J Mol Biol, 2001 Dec 7, 314(4), 735 - 49
Mechanism and cleavage specificity of the H-N-H endonuclease colicin E9; Pommer AJ et al.; Colicin endonucleases and the H-N-H family of homing enzymes share a common active site structural motif that has similarities to the active sites of a variety of other nucleases such as the non-specific endonuclease from Serratia and the sequence-specific His-Cys box homing enzyme I-PpoI . In contrast to these latter enzymes, however, it remains unclear how H-N-H enzymes cleave nucleic acid substrates . Here, we show that the H-N-H enzyme from colicin E9 (the E9 DNase) shares many of the same basic enzymological characteristics as sequence-specific H-N-H enzymes including a dependence for high concentrations of Mg2+ or Ca2+ with double-stranded substrates, a high pH optimum (pH 8-9) and inhibition by monovalent cations . We also show that this seemingly non-specific enzyme preferentially nicks double-stranded DNA at thymine bases producing 3'-hydroxy and 5'-phosphate termini, and that the enzyme does not cleave small substrates, such as dinucleotides or nucleotide analogues, which has implications for its mode of inhibition in bacteria by immunity proteins . The E9 DNase will also bind single-stranded DNA above a certain length and in a sequence-independent manner, with transition metals such as Ni2+ optimal for cleavage but Mg2+ a poor cofactor . Ironically, the H-N-H motif of the E9 DNase although resembling the zinc binding site of a metalloenzyme does not support zinc-mediated hydrolysis of any DNA substrate . Finally, we demonstrate that the E9 DNase also degrades RNA in the absence of metal ions . In the context of current structural information, our data show that the H-N-H motif is an adaptable catalytic centre able to hydrolyse nucleic acid by different mechanisms depending on the substrate and metal ion regime .

Curr Microbiol, 2002 Jan, 44(1), 44 - 8
Multi-copy repression of Serratia marcescens nuclease expression by dinI; Berkmen M et al.; The dinI homolog of S . marcescens was cloned from a plasmid library by virtue of its ability to inhibit nuclease expression from the S . marcescens nucA gene integrated in the genome of E . coli . The S . marcescens DinI protein is 68% identical to DinI of E . coli . It has a similar effect on other SOS regulated genes and likely exerts it effect on nuclease expression, which is most pronounced as the cells entered stationary phase, through inhibition of basal SOS expression.

Transfusion, 2001 Nov, 41(11), 1365 - 72
Identification of Yersinia-infected blood donors by anti-Yop IgA immunoassay; Kendrick CJ et al.; BACKGROUND: From 1991 through 1996, nine transfusion-related cases of septicemia and endotoxemia occurred in New Zealand, a rate approximately 80 times that in the United States . Eight cases involved the transfusion of Yersinia enterocolitica-infected blood and one involved Serratia liquefaciens-infected blood . Six of the recipients died . Donor exclusion by recent gastrointestinal illness failed to prevent the four most recent such infections, and it has led to an estimated 3- to 5-percent rate of donor deferral . STUDY DESIGN AND METHODS: An antigen preparation containing the released proteins (Yops) of Y . enterocolitica was used to establish an EIA to detect IgA directed against these proteins in donated blood . The assay was tested with serum from donors in transfusion-related endotoxemia cases, subjects who were stool culture-positive for Y . enterocolitica, and 495 healthy volunteer blood donors . RESULTS: The assay detected anti-Yop IgA in the donors of all 6 infected units tested . Ninety-six percent of culture-positive subjects tested positive, whereas there was 70-percent positivity with a commercial immunoassay based on lipopolysaccharide . Five percent of random donors tested positive; only one of these had Y . enterocolitica present in a stool sample, and none were bacteremic . CONCLUSION: The anti-Yop immunoassay used in this study could be applied to reduce the risk of posttransfusion endotoxic shock caused by Y . enterocolitica.

Mol Microbiol, 2001 Nov, 42(3), 835 - 49
Haem utilization in Vibrio cholerae involves multiple TonB-dependent haem receptors; Mey AR et al.; Vibrio cholerae has multiple iron transport systems, one of which involves haem uptake through the outer membrane receptor HutA . A hutA mutant had only a slight defect in growth using haemin as the iron source, and we show here that V . cholerae encodes two additional TonB-dependent haem receptors, HutR and HasR . HutR has significant homology to HutA as well as to other outer membrane haem receptors . Membrane fractionation confirmed that HutR is present in the outer membrane . The hutR gene was co-transcribed with the upstream gene ptrB, and expression from the ptrB promoter was negatively regulated by iron . A hutA, hutR mutant was significantly impaired, but not completely defective, in the ability to use haemin as the sole iron source . HasR is most similar to the haemophore-utilizing haem receptors from Pseudomonas aeruginosa and Serratia marcescens . A mutant defective in all three haem receptors was unable to use haemin as an iron source . HutA and HutR functioned with either V . cholerae TonB1 or TonB2, but haemin transport through either receptor was more efficient in strains carrying the tonB1 system genes . In contrast, haemin uptake through HasR was TonB2 dependent . Efficient utilization of haemoglobin as an iron source required HutA and TonB1 . The triple haem receptor mutant exhibited no defect in its ability to compete with its Vib- parental strain in an infant mouse model of infection, indicating that additional iron sources are present in vivo . V . cholerae used haem derived from marine invertebrate haemoglobins, suggesting that haem may be available to V . cholerae growing in the marine environment.

Parasitology, 2001 Nov, 123(Pt 5), 441 - 6
Microfloral diversity of cultured and wild strains of Psoroptes ovis infesting sheep; Hogg JC et al.; PCR amplification of 16S rDNA was used to determine the diversity of bacteria associated with 3 strains of sheep scab mite, Psoroptes ovis . Eight species of bacteria were identified by phylogenetic analysis of the PCR product sequences . Seven of these species are previously unreported in association with sheep scab mites . Five species were matched to Serratia marcesens, Proponibacteium acnes, Phyllobacterium rubiacearum, Pantoea agglomerans, Curacaobacter baltica, whereas the remaining 3 sequences matched unclassified sequences belonging to the gamma proteobacteria, pseudomonads and streptococci . Bacterial diversity of the in vivo cultured strain was very low and did not match the diversity of the 2 wild collected isolates . The diversity of the bacteria in relation to the disease of sheep scab and the possible importance of these bacteria in the diet of the mites are discussed.

J Bacteriol, 2001 Dec, 183(24), 7044 - 52
Characterization of Pseudomonas aeruginosa chitinase, a gradually secreted protein; Folders J et al.; The gram-negative bacterium Pseudomonas aeruginosa secretes many proteins into its extracellular environment via the type I, II, and III secretion systems . In this study, a gene, chiC, coding for an extracellular chitinolytic enzyme, was identified . The chiC gene encodes a polypeptide of 483 amino acid residues, without a typical N-terminal signal sequence . Nevertheless, an N-terminal segment of 11 residues was found to be cleaved off in the secreted protein . The protein shows sequence similarity to the secreted chitinases ChiC of Serratia marcescens, ChiA of Vibrio harveyi, and ChiD of Bacillus circulans and consists of an activity domain and a chitin-binding domain, which are separated by a fibronectin type III domain . ChiC was able to bind and degrade colloidal chitin and was active on the artificial substrates carboxymethyl-chitin-Remazol Brilliant Violet and p-nitrophenyl-beta-D-N,N',N"-triacetylchitotriose, but not on p-nitrophenyl-beta-D-N-acetylglucosamine, indicating that it is an endochitinase . Expression of the chiC gene appears to be regulated by the quorum-sensing system of P . aeruginosa, since this gene was not expressed in a lasIR vsmI mutant . After overnight growth, the majority of the ChiC produced was found intracellularly, whereas only small amounts were detected in the culture medium . However, after several days, the cellular pool of ChiC was largely depleted, and the protein was found in the culture medium . This release could not be ascribed to cell lysis . Since ChiC did not appear to be secreted via any of the known secretion systems, a novel secretion pathway seems to be involved.

Biomaterials, 2001 Dec, 22(24), 3225 - 33
A comparison of the use of an ATP-based bioluminescent assay and image analysis for the assessment of bacterial adhesion to standard HEMA and biomimetic soft contact lenses; Andrews CS et al.; The aim of this study was to investigate in vitro adhesion of clinically relevant bacteria to standard HEMA and novel biomimetic soft contact lenses (SCL) using bioluminescent ATP assay and image analysis . Unworn SCL were incubated with Pseudomonas aeruginosa, Staphylococcus epidermidis or Serratia marcescens suspended in sterile phosphate buffered saline (PBS) . The level of bacterial adhesion after 1, 2, 4, 6 and 18h, was assessed using both image analysis and a bioluminescent ATP assay . Species differences in the overall level of adhesion to the different types of lens were observed using both measurement techniques . Generally bacterial adhesion was shown to peak at 4-6 h, then decline to a much lower level by 18 h . After 4 h, adhesion of all species of bacteria to the biomimetic SCL (omafilcon A) was found to be significantly lower than to the standard HEMA SCL (polymacon) (p<0.05 . Student's t-test, n = 4) . Both these techniques demonstrated that novel biomimetic SCL materials exhibit significantly lower bacterial adhesion in vitro compared to standard HEMA SCL materials . SCL manufactured with these novel biomimetic materials may reduce the risk of infection.

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