South Med J, 1998 Apr, 91(4), 388 - 91 Endogenous endophthalmitis due to Serratia marcescens; Marinella MA et al.; Endogenous or metastatic bacterial endophthalmitis is a severe, sight-threatening infection of the vitreous humor that is only rarely due to Serratia marcescens . We report the case of a hemodialysis-dependent diabetic patient who had endogenous endophthalmitis of the right eye due to S marcescens, presumably from an infected dialysis catheter . The patient had total visual loss in the affected eye, which required enucleation. J Endod, 1998 Mar, 24(3), 176 - 9 Bacterial leakage of mineral trioxide aggregate as compared with zinc-free amalgam, intermediate restorative material, and Super-EBA as a root-end filling material; Fischer EJ et al.; Several dye leakage studies have demonstrated the fact that mineral trioxide aggregate (MTA) leaks significantly less than other root-end filling materials . The purpose of this study was to determine the time needed for Serratia marcescens to penetrate a 3 mm thickness of zinc-free amalgam, Intermediate Restorative Material (IRM), Super-EBA, and MTA when these materials were used as root-end filling materials . Fifty-six, single-rooted extracted human teeth were cleaned and shaped with a series of .04 Taper rotary instruments (Pro-series 29 files) . Once the canals were prepared in a crown down approach, the ends were resected and 48 root-end cavities were ultrasonically prepared to a 3 mm depth . The teeth were then steam sterilized . Using an aseptic technique, under a laminar air flow hood, the root-end cavities were filled with amalgam, IRM, Super-EBA, and MTA . Four root-end cavities were filled with thermoplasticized gutta-percha without a root canal sealer and served as positive controls . Another four root-end cavities were filled with sticky wax covered with two layers of nail polish and served as negative controls . The teeth were attached to presterilized (ethylene oxide gas) plastic caps, and the root ends were placed into 12-ml vials of phenol red broth . Using a micropipette, a tenth of a milliliter of S . marcescens was placed into the root canal of each tooth . To test the sterility of the apparatus set-up, the root canals of two teeth with test root-end filling materials and one tooth from the positive and negative control groups were filled with sterile saline . The number of days required for S . marcescens to penetrate the four root-end filling materials and grow in the phenol red broth was recorded and analyzed . Most of the samples filled with zinc-free amalgam leaked bacteria in 10 to 63 days . IRM began leaking 28 to 91 days . Super-EBA began leaking 42 to 101 days . MTA did not begin leaking until day 49 . At the end of the study, four of the MTA samples had not exhibited any leakage . Statistical analysis of the data indicated Mineral Trioxide Aggregate to be a most effective root-end filling material against penetration of S . marcescens. J Bacteriol, 1998 Apr, 180(8), 2262 - 4 Nuclease overexpression mutants of Serratia marcescens; Guynn LJ et al.; A family of mutants overexpressing the Serratia marcescens extracellular nuclease has been known for decades . A number of these alleles are characterized here at the molecular level, and the mutant genes are identified, yielding a likely model for their phenotype . The known mutations exert their effect indirectly on nucA expression by elevating the basal SOS response of the cell . Mutations have been found in xerC and uvrD, both of which result in partial SOS induction . A classic nucsu allele, that of strain W1050, is also likely to be in xerC. Can J Microbiol, 1998 Feb, 44(2), 149 - 56 Molecular characterization of Gluconobacter oxydans recA gene and its inhibitory effect on the function of the host wild-type recA gene; Liu YT et al.; A DNA fragment containing the recA gene of Gluconobacter oxydans was isolated and further characterized for its nucleotide sequence and ability to functionally complement various recA mutations . When expressed in an Escherichia coli recA host, the G . oxydans recA protein could efficiently function in homologous recombination and DNA damage repair . The recA gene's nucleotide sequence analysis revealed a protein of 344 amino acids with a molecular mass of 38 kDa . We observed an E . coli-like LexA repressor-binding site in the G . oxydans recA gene promoter region, suggesting that a LexA-like mediated response system may exist in G . oxydans . The expression of G . oxydans recA in E . coli RR1, a recA+ strain, surprisingly caused a remarkable reduction of the host wild-type recA gene function, whereas the expression of both Serratia marcescens recA and Pseudomonas aeruginosa recA gene caused only a slight inhibitory effect on function of the host wild-type recA gene product . Compared with the E . coli RecA protein, the identity of the amino acid sequence of G . oxydans RecA protein is much lower than those RecA proteins of both S . marcescens and Pseudomonas aeruginosa . This result suggests that the expression of another wild-type RecA could interfere with host wild-type recA gene's function, and the extent of such an interference is possibly correlated to the identity of the amino acid sequence between the two classes of RecA protein. Mol Microbiol, 1998 Mar, 27(5), 941 - 52 Serratia marcescens S-layer protein is secreted extracellularly via an ATP-binding cassette exporter, the Lip system; Kawai E et al.; The Serratia marcescens Lip exporter belonging to the ATP-binding cassette (ABC) exporter is known to be involved in signal peptide-independent extracellular secretion of a lipase and a metalloprotease . Although the genes of secretory proteins and their ABC exporters are usually all reported to be linked in several gram-negative bacteria, neither the lipase nor the protease gene is located close to the Lip exporter genes, lipBCD . A gene (slaA) located upstream of the lipBCD genes was cloned, revealing that it encodes a polypeptide of 100 kDa and is partially similar to the Caulobacter crescentus paracrystalline cell surface layer (S-layer) protein . The Lip exporter-deficient mutants of S . marcescens failed to secrete the SlaA protein . Electron micrography demonstrated the cell surface layer of S . marcescens . The S-layer protein was secreted to the cultured media in Escherichia coli cells carrying the Lip exporter . Three ABC exporters, Prt, Has and Hly systems, could not allow the S-layer secretion, indicating that the S . marcescens S-layer protein is strictly recognized by the Lip system . This is the first report concerning secretion of an S-layer protein via its own secretion system. Microbiology, 1998 Mar, 144 ( Pt 3), 639 - 53 Re-evaluation of the serotypes of Serratia marcescens and separation into two schemes based on lipopolysaccharide (O) and capsular polysaccharide (K) antigens; Aucken HM et al.; Chemical and serological analysis has revealed that many of the 29 O serotype reference strains of Serratia marcescens contain both neutral and acidic polysaccharides which correspond to LPS O antigens and capsular K antigens, respectively . New O and K antigen typing schemes have therefore been devised, based on the known chemical structures of the surface polysaccharides of the organism . These schemes were designed to allow the specific detection of these antigens on unknown strains using ELISAs . O antigens were detected using whole cells cultured in broth then autoclaved to remove capsular material, while K antigens were detected using formolized whole cells which had been cultured on glycerol agar to enhance capsule production . After testing with the 29 reference strains as well as 423 distinct clinical strains, it was apparent that different aspects of chemical structure were associated with different degrees of serological reactivity and the typing schemes were modified further to accommodate this . In general, the O antigen repeating unit structures were chemically simple with di- or trisaccharide backbones . Serological specificity was often provided solely by the presence or absence of an O-acetyl substituent, or a change in the linkage between two sugar residues . Five of the O serotypes in the new scheme were represented by 12 of the 29 reference strains, while three reference strains lacked O antigens altogether, resulting in the elimination of 10 of the original O types . In contrast, the K antigen repeating unit structures were more complex and chemically diverse, having at least four sugar residues . Three K types were each seen in two reference strains while 12 of the 29 reference strains were acapsular . Thus, the resulting schemes contain 19 O types and 14 K types and allow the definitive serotype identification of S . marcescens. J Antimicrob Chemother, 1998 Feb, 41(2), 189 - 95 Contribution of overproduced chromosomal beta-lactamase and defective outer membrane porins to resistance to extended-spectrum beta-lactam antibiotics in Serratia marcescens; Weindorf H et al.; Using clinical strains of Serratia marcescens with low and high resistance to extended-spectrum beta-lactam antibiotics, the relative contribution of chromosomal beta-lactamase and defective outer membrane porins to resistance was determined . Low-level resistance was caused by overproduced beta-lactamase alone . High-level resistance was due to beta-lactamase overproduction and defects of porin OmpF or OmpF and OmpC . Overproduction of beta-lactamase in bacteria with both degrees of resistance was eliminated by transformation with cloned ampD+, the gene (from Escherichia coli) for negative modulation of beta-lactamase induction . In transformants of highly resistant bacteria with normally low and inducible beta-lactamase production, the remaining porin defects alone imparted only minimal resistance to extended-spectrum beta-lactam antibiotics. Braz J Med Biol Res, 1997 Nov, 30(11), 1291 - 8 Detection of cytotoxic activity on Vero cells in clinical isolates of Serratia marcescens; Carbonell GV et al.; Cytotoxin production was studied in 60 Serratia marcescens strains isolated from hospitalized patients . Association of cytotoxic activity with serotype, source of isolation and presence of plasmids was also evaluated . Thirteen of the 60 S . marcescens strains produced a cytotoxic effect on Vero cells . These strains were isolated from distinct clinical sources and classified into seven different serotypes (O1:H7; O4:NM; O10:NT; O19:NM; O6,14:H4; O6,14:NM and O6,14:H1) . No relationship was observed between cytotoxic activity and clinical source or serotypes of the strains . Plasmids from five cytotoxin-producing S . marcescens strains were transferred to E . coli K12/711 . The transconjugants did not exhibit cytotoxicity, indicating that the cytotoxic effect is not plasmid-mediated among these strains . Although a cytotoxic activity was demonstrated in filtrates of some S . marcescens strains, further studies should be performed to assess the role of this toxin in pathogenesis. Optom Vis Sci, 1998 Feb, 75(2), 126 - 31 Antimicrobial efficiency of hydrogel contact lens soaking solutions marketed in Spain; Durban JJ et al.; The antimicrobial efficiency of 20 commercially available solutions for soaking and rinsing soft contact lenses was studied in relation to 5 bacteria (Escherichia coli, Staphylococcus epidermidis, Pseudomonas aeruginosa, Bacillus subtilis, and Serratia marcescens) and 1 fungus (Candida albicans) . Each product was separately inoculated with each of six microorganisms, and samples of the inoculated contact lens solutions were taken at predetermined times, placed in a recovery medium, and incubated . Where there was growth, the colonies were counted . There were differences in performance even between solutions labeled as having the same antimicrobial content . One of the solutions marketed in Spain to soak hydrogel contact lenses failed to inactivate all six test strains. Biosci Biotechnol Biochem, 1998 Jan, 62(1), 128 - 35 Chitin binding protein (CBP21) in the culture supernatant of Serratia marcescens 2170; Suzuki K et al.; A chitin binding protein (CBP21) 21 kDa in size, is a major protein in the culture supernatant when Serratia marcescens 2170 is grown in the presence of chitin . The gene (cbp) for CBP21 was found to be located in a region 1.5 kb downstream of the chiB gene encoding chitinase B . The cbp gene encodes a polypeptide of 197 amino acids with a calculated size of 21.6 kDa containing a putative signal sequence of 27 amino acids . Comparison of the amino acid sequence of the deduced polypeptide with that of other proteins showed that CBP21 is similar (45.3% amino acid identity) to CHB1 of Streptomyces olivaceoviridis . Purified CBP21 prepared from the periplasmic fraction of Escherichia coli carrying the cloned cbp gene showed its highest binding activity to squid chitin (beta-chitin) followed by colloidal chitin and regenerated chitin . Binding of CBP21 to regenerated chitin was affected by pH, in particular, low pH reduced binding activity markedly . The presence of similar chitin binding proteins in the distantly related microorganisms, Streptomyces and Serratia, suggests a wide distribution of this type of chitin binding protein in chitinolytic microorganisms. FEMS Microbiol Lett, 1998 Mar 1, 160(1), 151 - 8 Cloning of the 52-kDa chitinase gene from Serratia marcescens KCTC2172 and its proteolytic cleavage into an active 35-kDa enzyme; Gal SW et al.; A chitinase gene (pCHI52) encoding the 52-kDa chitinase was isolated from a Serratia marcescens KCTC2172 cosmid library . This chitinase gene consists of 2526 bp with an open reading frame that encodes 485 amino acids . Escherichia coli harboring the pCHI52 gene secreted not only a 52-kDa but also a 35-kDa chitinase into the culture supernatant . We purified both 52-kDa and 35-kDa chitinases using a chitin affinity column and Sephacryl-S-300 gel filtration chromatography . We determined that the 17 N-terminal amino acid sequences of the 52-kDa and the 35-kDa chitinase are identical . Furthermore, a protease obtained from S . marcescens KCTC2172 cleaved the 52-kDa chitinase into the 35-kDa protein with chitinase activity . These results suggest that the 35-kDa chitinase derives from the 52-kDa chitinase by post-translational proteolytic modification . The optimal reaction temperature of 45 degrees C and the optimal pH of 5.5 were identical for both enzymes . The specific activities of the 52-kDa and 35-kDa chitinases on natural swollen chitin were 67 mumol min-1 mg-1 and 60 mumol min-1 mg-1, respectively. Eur J Biochem, 1998 Feb 1, 251(3), 924 - 34 Biochemical characterization of Anabaena sp . strain PCC 7120 non-specific nuclease NucA and its inhibitor NuiA; Meiss G et al.; We have established overexpression systems and purification protocols for NucA and NuiA, a sugar non-specific nuclease and its protein inhibitor from Anabaena sp . strain PCC 7120, in order to characterize these proteins in detail . CD spectroscopy revealed that NucA has a similar secondary-structure composition, 13% alpha helix and 20% beta sheet, to the related Serratia nuclease, while NuiA represents a protein with a higher alpha-helical (29%) and beta-sheet (24%) content than NucA . Denaturation experiments showed that the stabilities of NucA and NuiA are in the typical range for proteins of mesophilic organisms, NuiA with deltaG0H2O = 63.4 J x mol(-1)residue, being slightly more stable than its target NucA with delta deltaG0H2O = 46.3 J x mol(-1)residue . The nuclease requires divalent metal ions as cofactors, the optimum concentration being around 5 mM for Mn2+ or Mg2+ . The order of effectiveness of various divalent cations to function as cofactors for the hydrolytic activity of NucA is Mn2+ = Co2+ > Mg2+ > or = Ni2+ >> or Ca2+ = Cd2+ at a concentration of 5 mM . Nuclease activity decreases with increasing concentration of monovalent salt . The activity of NucA shows a pH optimum at pH 5.5-7.5 . The temperature optimum is around 35 degrees C, the activation energy was calculated to be 53 kJ mol(-1) . The specific activity of the nuclease towards high molecular-mass DNA is 8.4 x 10(6) Kunitz-units x mg(-1), which means that NucA is one of the most active nucleases known . Kinetic constants for the cleavage of various DNA and RNA substrates by NucA are all in the range Km < or = 0.1 mg x ml(-1) and k(cat) approximately 1000 s(-1) . As other non-specific nucleases, NucA exhibits sequence preferences, similar to the related Serratia nuclease, NucA avoids cleavage of d(A) x d(T) tracts . The nucleolytic activity of NucA is completely inhibited at equimolar concentrations of nuclease and inhibitor . An ultracentrifugation analysis showed that NucA and NuiA form a 1:1 complex . The interaction of NucA with NuiA was also investigated by CD spectroscopy and revealed no major conformational changes upon complex formation of the two proteins. J Infect, 1997 Nov, 35(3), 303 - 4 Community-acquired Serratia marcescens meningitis; Peeters A et al.; Serratia marcescens is an unusual cause of community-acquired meningitis in adults . We report a case of S . marcescens meningitis occurring 29 years after a head injury and preceded by 3 years of intermittent nasal discharge of cerebrospinal fluid (CSF) . One month before admission, the patient had received treatment with cefadroxil . This case illustrates the risk of Gram-negative bacillary meningitis in patients with a CSF leak when they are treated with antibiotics . When patients have a chronic clear nasal discharge, one should look for a past medical history of head injury before prescribing antibiotics . In the presence of a fistula, any antibiotherapy may lead to the selection of resistant organisms which may be difficult to treat . Due to the high risk of meningitis and the fact that spontaneous closure in delayed CSF rhinorrhoea is unlikely, surgical repair of any associated fistulae is mandatory. Fold Des, 1997, 2(5), 291 - 4 Evolution of immunoglobulin-like modules in chitinases: their structural flexibility and functional implications; Perrakis A et al.; BACKGROUND: Chitinase A from Serratia marcescens is a glycosyl hydrolase consisting of three distinct domains . The N-terminal domain (ChiN domain, amino acids 24-137) has an immunoglobulin-like fold . This ChiN domain is structurally similar to fibronectin type III domains (FnIII domains), which exist in other chitinases, but does not share any sequence similarity with them . RESULT: Structure comparisons of the ChiN domain and FnIII domains confirm the similar fold, but fail to establish any sequence similarity . Sequence searches and comparisons between ChiN and FnIII domain sequences show a remarkable difference between the two domains in chitinases from an evolutionary point of view . A low temperature structure of chitinase A shows that the ChiN module is flexible with respect to the catalytic body of the protein . CONCLUSIONS: We postulate that the ChiN and FnIII domains evolved independently in chitinases which share otherwise homologous catalytic domains . The flexibility of the ChiN domain, together with biochemical knowledge of the function of similar domains, leads us to propose that immunoglobulin-like folds in chitinases are involved in interactions with the chitin chain during catalysis. J Bacteriol, 1998 Feb, 180(3), 742 - 5 Two separate regulatory systems participate in control of swarming motility of Serratia liquefaciens MG1; Givskov M et al.; Swarming motility of Serratia liquefaciens MG1 requires the expression of two genetic loci, flhDC and swrI . Here we demonstrate that the products of the flhDC operon (the flagellar master regulator) and the swrI gene (the extracellular signal molecule N-butanoyl-L-homoserine lactone) are global regulators which control two separate regulons. Biochemistry (Mosc), 1997 Sep, 62(9), 983 - 8 Isoforms of Serratia marcescens nuclease . The role of Mg2+ in the hydrolysis mechanism; Filimonova MN et al.; Structural and functional differences between isoforms Sm1 and Sm2, a lack of influence of free Mg2+ on the isoform structures, formation of DNA-magnesium complex serving with great probability as a real substrate for the nuclease has been summarized on the basis of experimental data . Mg2+ forming a complex with phosphate groups of DNA are supposed to further increase the electrophilicity of the phosphorus atoms besides causing a conformational change of the substrate. Biochem J, 1997 Dec 15, 328 ( Pt 3), 945 - 9 Serratia marcescens chitobiase is a retaining glycosidase utilizing substrate acetamido group participation; Drouillard S et al.; The stereochemistry of the reaction catalysed by Serratia marcescens chitobiase was determined by HPLC separation of the anomers of N-acetylglucosamine produced during the hydrolysis of p-nitrophenyl N-acetyl-beta-d-glucosaminide (PNP-GlcNAc) . In the early stages of the reaction, the beta-anomer was found to prevail, whereas the alpha-anomer dominated at mutarotation equilibrium . This established that chitobiase hydrolyses glycosidic bonds with overall retention of the anomeric configuration . Chitobiase-catalysed hydrolysis of PNP-GlcNAc was competitively inhibited by a series of chito-oligosaccharides (degree of polymerization 2-5) that were selectively de-N-acetylated at their non-reducing end . The results are in accord with the participation of the acetamido group at C-2 of the substrate in the catalytic mechanism of chitobiase and related enzymes. Zentralbl Veterinarmed B, 1997 Nov, 44(9), 537 - 46 Pathology of Serratia marcescens mastitis in cattle; Di Guardo G et al.; Microbiological, cytological, histopathological, and immunohistochemical investigations were carried out on four dairy cows affected by Serratia marcescens mastitis . The animals under study were from a herd of 120 lactating cows bred in the province of Rome . In the above herd, S . marcescens mastitis showed a prevalence of 20.8% . S . marcescens was the only bacterial agent isolated, prior to and after slaughter, from the teat milk, the mammary gland and the supramammary lymph nodes of the four cows under study . Cytologically, the four subjects exhibited high cell counts in their milk, with an average of up to 5,570,000 cells/ml in S.marcescens-infected quarters . Macroscopically, nodular lesions were apparent scattered throughout the mammary parenchyma, with enlargement of the regional lymph nodes . Histologically, a chronic, non-purulent mastitis, characterized by a marked fibrous tissue proliferation and the coexistence of corpora amylacea within the glandular alveoli, was observed in association with chronic hyperplastic lymphadenitis involving the supramammary lymph nodes of the four cows . Immunohistochemically, S . marcescens was demonstrated, by means of monoclonal antibodies, both in the mammary gland and in the supramammary lymph nodes from these four animals. Antimicrob Agents Chemother, 1998 Jan, 42(1), 190 - 3 Cloning and nucleotide sequence of the DNA gyrase gyrA gene from Serratia marcescens and characterization of mutations in gyrA of quinolone-resistant clinical isolates; Kim JH et al.; The sequence of the DNA gyrase gyrA gene of Serratia marcescens ATCC 14756 was determined . An open reading frame of 2,640 nucleotides coding for a polypeptide with a calculated molecular mass of 97,460 was found, and its sequence complemented the sequence of an Escherichia coli gyrA temperature-sensitive mutation . Analysis of the PCR products of the quinolone resistance-determining regions of gyrA genes from six quinolone-resistant clinical isolates revealed a single amino acid substitution, Ser-83 to Arg or Asp-87 to Tyr, in all six mutants, suggesting that a mutational alteration in gyrA is a common mechanism of quinolone resistance in S . marcescens. Antimicrob Agents Chemother, 1998 Jan, 42(1), 176 - 9 Sequences of homologous beta-lactamases from clinical isolates of Serratia marcescens with different substrate specificities; Matsumura N et al.; Genes for two group 1 beta-lactamases, SRT-1 and SST-1, were sequenced . These beta-lactamases were produced by clinical isolates of Serratia marcescens, isolates GN16694 and GN19450, respectively . The resulting enzymes were 96% identical . SRT-1 hydrolyzed oxyimino cephalosporins, but SST-1 hardly hydrolyzed them . At residue 213 in the third motif, which is conserved among group 1 beta-lactamases, SRT-1 and SST-1 had Lys and Glu, respectively . By site-directed mutagenesis, the substitution of Glu by Lys at residue 213 in SST-1 resulted in an enzyme that hydrolyzed oxyimino cephalosporins. Chemotherapy, 1998 Jan-Feb, 44(1), 36 - 41 Preventive effect of dapsone on renal scarring following mannose-sensitive piliated bacterial infection; Mochida O et al.; Renal scarring has been thought to occur in the later stages of chronic pyelonephritis . We previously reported that mannose-sensitive (MS) piliated bacteria promoted renal scarring, which was prevented by antioxidants . The preventive effect of diaphenylsulfone (dapsone), which has a scavenging activity on active oxygen species, on renal scarring was examined . Female Sprague-Dawley rats were inoculated with clinical isolates of Serratia marcescens which had both MS and mannose-resistant pili or with recombinant strains which had MS pili on their surface; they were then administered 20 mg/kg of dapsone or not . Dapsone significantly suppressed scarring following infection of the kidney . The bacterial counts in the kidneys were not different in dapsone-treated and nontreated rats . We conclude that dapsone is effective in preventing renal scarring, and it is suggested that the clinical use of this drug may prevent renal scar formation following pyelonephritis. Cornea, 1998 Jan, 17(1), 74 - 8 Platinum spatula versus Mini-tip Culturette in culturing bacterial keratitis; Epley KD et al.; PURPOSE: To compare the traditional method of culturing bacterial keratitis (platinum spatula) with the use of a commercially available Mini-tip Culturette (Becton-Dickinson, Cockeysville, MD, U.S.A.) . METHODS: An experimental model of bacterial keratitis was created in rabbit corneas by intrastromal injection of bacteria . Cultures were taken of rabbit corneas with both the Mini-tip Culturette and the platinum spatula . Culture results were compared with corneal colony counts . Humans with community-acquired presumed bacterial keratitis were cultured with both the Mini-tip Culturette and the platinum spatula . The sensitivity and specificity of the Mini-tip Culturette method was determined and compared with the platinum-spatula technique . RESULTS: Rabbit keratitis model: 100% of corneas had established infections by colony count . Each ulcer was culture positive with platinum spatula, moist Mini-tip Culturette, and dry Mini-tip Culturette . Human keratitis: Seven patients had culture-negative keratitis with both the Mini-tip Culturette and the platinum spatula . Five patients were culture positive with both the Mini-tip Culturette and the platinum spatula . One of the positive cultures had growth of multiple organisms by using the platinum spatula but not with the Mini-tip Culturette . The sensitivity of the Mini-tip Culturette was 83.3% . The specificity of the Mini-tip Culturette was 100% . Detected organisms included group A beta-hemolytic Streptococcus, S . aureus, coagulase-negative Staphylococcus, Serratia marcescens, and Pseudomonas aeruginosa . CONCLUSION: The Mini-tip Culturette is a highly specific and moderately sensitive method for culturing bacterial keratitis. Can J Microbiol, 1997 Nov, 43(11), 1069 - 73 Serratia entomophila bacteriophages: host range determination and preliminary characterization; O'Callaghan M et al.; Eight bacteriophages specific to Serratia entomophila, a commercially available bacterial pathogen of the New Zealand grass grub (Costelytra zealandica), were characterized by host range determination, morphology and restriction endonuclease patterns of DNA . Phages were originally isolated from grass grub larvae and fermenter broth where phages had disrupted large-scale production of S . entomophila . Seven of the phages (CW1-CW5, BC, and BT) had heads similar in size (approximately 60 x 60 nm) and long noncontractile tails (185 x 10 nm) . Phage AgRP8 (P8) had a smaller head and a short tail structure . Restriction endonuclease analysis divided the phages into four groups: CW2, CW4, CW5, BC, and BT gave identical patterns, white CW1, CW3, and P8 each gave different patterns . Six distinct phage groups were distinguished by host range determination, after screening phages against 70 bacterial isolates: CW1, CW2/CW4, CW3, CW5, BC/BT, and P8 . While confirming the indicated groupings by DNA analysis, it was possible to distinguish between some of the phages in the largest group: CW2/4 could be distinguished from CW5 and BC/BT . Screening of soil bacterial isolates of S . entomophila against nondiluted phages will aid in monitoring the establishment and persistence of strains applied for biological control of the grass grub. Immunol Cell Biol, 1997 Oct, 75(5), 484 - 91 Use of degenerate primers and heat-soaked polymerase chain reaction (PCR) to clone a serine protease antigen from Dermatophilus congolensis; Mine OM et al.; Serine proteases are thought to be involved in the initial attack on sheep skin by Dermatophilus congolensis and are obvious antigens for inclusion in a vaccine to prevent lumpy wool disease (dermatophilosis) . Degenerate primers were designed after alignment of seven bacterial serine proteases . Inosine was incorporated into the primers at positions of three- and four-base redundancy, and this reduced the complexity of the primer mixtures from several thousand to sixteen different sequences for each primer . The primers were validated by production and sequencing of amplicons from serine protease genes in Bacillus subtilis and Serratia marcescens . The primers were used with heat-soaked polymerase chain reaction (PCR) to produce amplicons from two D . congolensis strains, AG and MB . In the amplicon codons for arginine, rather than the expected serine, were found where inosine was used for both the first and third positions for a codon in the primer . A search with the deduced amino acid sequences of the amplicons showed significant similarity to a keratinase and other serine proteases from various organisms . Similarity was most apparent around the active site residues and other essential secondary structural elements. Mol Microbiol, 1997 Dec, 26(5), 853 - 65 Specific phosphatidylethanolamine dependence of Serratia marcescens cytotoxin activity; Hertle R et al.; The cytolytic and haemolytic activity of Serratia marcescens is determined by the ShlA protein, which is secreted across the outer membrane with the aid of the ShlB protein . In the absence of ShlB, inactive ShlA* remains in the periplasm of Escherichia col transformed with an shlA-encoding plasmid, which indicates that ShlB converts ShlA* to active ShlA . ShlA* in a periplasmic extract and partially purified ShlA* were activated in vitro by partially purified ShlB . When both proteins were highly purified, ShlA* was only activated by ShlB when phosphatidylethanolamine (PE) or phosphatidylserine was added to the assay, while phosphatidylglycerol contributed little to ShlA* activation . Lyso-PE, cardiolipin, phosphatidylcholine, phosphatidic acid, lipopolysaccharide and various detergents could not substitute for PE . Although radioactively labelled PE was so tightly associated with ShlA that it remained bound to ShlA after heating and SDS-PAGE, it was not covalently linked to ShlA as PE could be removed by thin-layer chromatography with organic solvents . The number of PE molecules associated per molecule of ShlA was 3.9 +/- 2.2 . Active ShlA was inactivated by treatment with phospholipase A2, which indicated that PE is also required for ShlA activity . ShlA-255 (containing the 255 N-terminal amino acids of ShlA) reversibly complemented ShlA* to active ShlA and was inactivated by phospholipase A2, which demonstrated that PE binds to the N-terminal portion of ShlA; this region has previously been found to be involved in ShlA secretion and activation . Electrospray mass spectroscopy of ShlA-255 determined a molar mass that corresponded to that of unmodified ShlA-255 . An E . coli mutant that synthesized only minute amounts of PE did not secrete ShlA but contained residual cell-bound haemolytic activity . Since PE binds strongly to ShlA* in the absence of ShlB without converting ShlA* to haemolytic ShlA, ShlB presumably imposes a conformation on ShlA that brings PE into a position to mediate interaction of the hydrophilic haemolysin with the lipid bilayer of the eukaryotic membrane. Cardiovasc Surg, 1997 Dec, 5(6), 579 - 83 Aortic valve or root replacement with cryopreserved homograft for active infectious endocarditis; Riberi A et al.; Active aortic endocarditis is a serious condition that carries a high mortality and morbidity . The aim of this study was to analyse results obtained from 24 patients who underwent aortic valve or root replacement with cryopreserved homograft for aortic endocarditis . Eleven patients had native valve endocarditis, and 13 had prosthetic valve endocarditis . The mean age was 47.7 years: there were seven women and 17 men . Causative organisms were staphylococci (12), streptococci (four), serratia (one), candida (one), pneumococci (one), while no organisms were isolated in the remaining five patients . Complete reconstruction of the aortic annulus with homograft conduits was necessary in 20 patients (six total root and 14 mini-root) . Infracoronary homograft aortic valve replacement was performed in the remaining patients . One patient died 1 day after the operation from ventricular failure, and two others died after 4 and 6 months as a result of arrhythmia . One patient died of recurrent endocarditis 1 year after surgery . The actuarial survival rate at 3 years was 83.4% . All survivors are symptom-free, with no evidence of recurrent endocarditis . Doppler echocardiography showed minimal aortic regurgitation in four patients. Pediatr Infect Dis J, 1997 Nov, 16(11), 1045 - 8 Patient density, nurse-to-patient ratio and nosocomial infection risk in a pediatric cardiac intensive care unit; Archibald LK et al.; BACKGROUND: An investigation of a Serratia marcescens outbreak in a pediatric cardiac intensive care unit (CICU) suggested that understaffing or overcrowding might have been underlying risk factors . OBJECTIVE: To assess the effect of fluctuations in CICU nurse staffing levels and patient census on CICU nosocomial infection rate (NIR) . METHODS: The monthly CICU nursing hours, patient days and nosocomial infections were obtained from retrospective review of administrative, patient and microbiology records during December, 1994, through December, 1995 (study period) . The NIR and nursing hours:patient day ratio were then calculated . The correlations between NIR vs . nursing hours, patient days and nursing hours:patient day ratio were determined . RESULTS: The median monthly CICU NIR was 6.9 (range, 0 to 15.2) infections per 1000 patient days; the median number of hours worked per month by CICU registered nurses was 7754 (range, 7133 to 8452) hours; the median number of patient days treated per month was 507 (range, 381 to 590) patient days; and the median monthly nursing hours:patient day ratio was 15.2:1 (range, 13.2:1 to 19.9:1) . The strongest linear correlation was observed between the monthly NIR and patient days (r = 0.89, P = 0.0001) . There was an inverse correlation between the monthly NIR and nursing hours:patient day ratio (r = -0.77, P = 0.003) . CONCLUSIONS: The NIR was most strongly correlated with patient census but also was strongly associated with the nursing hours:patient day ratio . These factors may influence the infection rate because of breaks in health care worker aseptic technique or decreased hand washing . Increased patient census alone may increase the risk of cross-transmission of nosocomial infections . As hospitals proceed with cost containment efforts the effect of fluctuations in patient census and nurse staffing on patient outcomes needs evaluation. Dermatology, 1997, 195 Suppl 2, 19 - 28 Comparison of bactericidal effects of commonly used antiseptics against pathogens causing nosocomial infections . Part 2; Yasuda T et al.; Opportunistic infections caused by gram-negative rods (GNR), conventionally regarded as organisms with low or no pathogenicity, and intractable infections caused by various resistant organisms pose a great problem now . In view of this, we determined the bactericidal effects of 5 commonly used disinfectants using as the test strains Xanthomonas maltophilia and Serratia marcescens, chosen among other GNR since they often cause nosocomial infections . Regarding the bactericidal activities against X . maltophilia and S . marcescens, both sensitive strains and resistant strains were killed within 20 s of exposure to povidone-iodine and sodium hypochlorite . With chlorhexidine, 1 strain each of both species was not killed within 10 min of exposure at a concentration of 0.2% . Both sensitive strains and resistant strains of X . maltophilia were killed within 20 s of exposure to benzalkonium at 0.02%, while a concentration of 0.1% was required for benzalkonium to kill S . marcescens within 20 s . With Tego-51, both sensitive strains and resistant strains of X . maltophilia were killed within 20 s at 0.02%, while 1 strain of S . marcescens was not killed within 20 s at a concentration of 0.1% . In the use of disinfectants, comparative bactericidal effects of various disinfectants against clinical isolates should be taken into consideration. J Med Microbiol, 1997 Dec, 46(12), 1019 - 28 An epidemiological study of Serratia marcescens isolates from nosocomial infections by enzyme electrophoresis; Goullet P et al.; Serratia marcescens isolates from 164 patients with suspected nosocomial infection in several hospitals in the greater Paris region were investigated by analysis of the electrophoretically demonstrable allelic variations of gene loci coding for five esterases and five other enzymes . All the loci were polymorphic and the mean number of alleles per locus was 6.1 . A total of 72 distinctive electrophoretic types (ETs) representing multilocus genotypes was distinguished . The isolates were divided into two groups according to their resistance to antibiotics: 82 multiresistant isolates (MRI) and 82 relatively susceptible isolates (RSI) . Seventy-two MRI (88%) were in four genetically related ETs: ET1, ET2, ET8 and ET9; ET1 was found in 48 isolates, whereas the remaining MRI were in 10 ETs, and all RSI in 61 ETs . Three ETs contained both MRI and RSI . The mean coefficients of genetic diversity for the 10 enzyme loci among ETs and isolates were smaller for MRI than for RSI, while the modal ET of MRI resembled that of RSI . The epidemiological significance of isolates varied according to their ET . Thus, isolates belonging to ET1, ET2 and ET8 were responsible for outbreaks or for sporadic infections, whereas isolates of other ETs were responsible for only sporadic infections . The temporal distribution of ET1 isolates among hospitals identified seven outbreaks in seven clinical departments. Biol Pharm Bull, 1997 Nov, 20(11), 1136 - 40 Inhibition of the metallo-beta-lactamase produced from Serratia marcescens by thiol compounds; Goto M et al.; Low molecular weight thiol compounds have been found to be strong inhibitors of metallo-beta-lactamase (IMP-1) produced by Serratia marcescens TN9106, which was expressed by Echerichia coli JM109 cells . Mercaptoacetic acid and 2-mercaptopropionic acid strongly and competitively inhibited IMP-1 with Ki of 0.23 and 0.19 microM, respectively . 2-Mercaptoethanol reversibly inhibited IMP-1 but did not show simple competitive inhibition. Virology, 1997 Nov 24, 238(2), 243 - 53 Liquefaction of Autographa californica nucleopolyhedrovirus-infected insects is dependent on the integrity of virus-encoded chitinase and cathepsin genes; Hawtin RE et al.; We examined the role of the Autographa californica nucleopolyhedrovirus (AcMNPV)-encoded chitinase in virus pathogenesis in Trichoplusia ni larvae . In conjunction with the AcMNPV-encoded cathepsin, it promotes liquefaction of the host in the latter stages of infection . Insects infected with virus mutants lacking either the chitinase A gene (chiA) or cathepsin gene (cath) remained intact several days after death . However, if both viruses were used to infect insects, liquefaction of the host was restored . Chitinase was readily detected in AcMNPV-infected insects using a chitinase-specific antibody, but it was absent from insects infected with a chiA deletion mutant (AcchiA-) . The chitinase was also detected in polyhedra purified from AcMNPV-infected insects but not in those from AcchiA- . However, polyhedra derived from a virus lacking an intact chiA were no less effective in initiating an infection in second instar T . ni larvae than those of the unmodified AcMNPV . It was also demonstrated that the virus chitinase retained high levels of activity between pH 3.0 and 10.0 . In contrast, chitinases isolated from Serratia marcescens, although active under acidic conditions, rapidly lost activity above pH 7.0 illustrating that despite 57% sequence identity, the two proteins have distinct enzymic activities. J Bacteriol, 1997 Dec, 179(23), 7581 - 6 A gene (wbbL) from Serratia marcescens N28b (O4) complements the rfb-50 mutation of Escherichia coli K-12 derivatives; Rubires X et al.; A cosmid-based genomic library of Serratia marcescens N28b was introduced into Escherichia coli DH5alpha, and clones were screened for serum resistance . One clone was found resistant to serum, to bacteriocin 28b, and to bacteriophages TuIa and TuIb . This clone also showed O antigen in its lipopolysaccharide . Subcloning and sequencing experiments showed that a 2,124-bp DNA fragment containing the rmlD and wbbL genes was responsible for the observed phenotypes . On the basis of amino acid similarity, we suggest that the 288-residue RmlD protein is a dTDP-L-rhamnose synthase . Plasmid pJT102, containing only the wbbL gene, was able to induce O16-antigen production and serum resistance in E . coli DH5alpha . These results suggest that the 282-residue WbbL protein is a rhamnosyltransferase able to complement the rJb-50 mutation in E . coli K-12 derivatives, despite the low level of amino acid identity between WbbL and the E . coli rhamnosyltransferase (24.80%) . S . marcescens N28b rmlD and wbbL mutants were constructed by mobilization of suicide plasmids containing a portion of rmlD or wbbL . These insertion mutants were unable to produce O antigen; since strain N28b produces O4 antigen, these results suggest that both genes are involved in O4-antigen biosynthesis. J Bacteriol, 1997 Nov, 179(22), 7111 - 7 Genetic analysis of the chitinase system of Serratia marcescens 2170; Watanabe T et al.; To carry out a genetic analysis of the degradation and utilization of chitin by Serratia marcescens 2170, various Tn5 insertion mutants with characteristic defects in chitinase production were isolated and partially characterized . Prior to the isolation of the mutants, proteins secreted into culture medium in the presence of chitin were analyzed . Four chitinases, A, B, C1, and C2, among other proteins, were detected in the culture supernatant of S . marcescens 2170 . All four chitinases and a 21-kDa protein (CBP21) lacking chitinase activity showed chitin binding activity . Cloning and sequencing analysis of the genes encoding chitinases A and B of strain 2170 revealed extensive similarities to those of other strains of S . marcescens described previously . Tn5 insertion mutagenesis of strain 2170 was carried out, and mutants which formed altered clearing zones of colloidal chitin were selected . The obtained mutants were divided into five classes as follows: mutants with (i) no clearing zones, (ii) fuzzy clearing zones, (iii) large clearing zones, (iv) delayed clearing zones, and (v) small clearing zones . Preliminary characterization suggested that some of these mutants have defects in chitinase excretion, a negatively regulating mechanism of chitinase gene expression, an essential factor for chitinase gene expression, and a structural gene for a particular chitinase . These mutants could allow researchers to identify the genes involved in the degradation and utilization of chitin by S . marcescens 2170. Antimicrob Agents Chemother, 1997 Nov, 41(11), 2374 - 82 Characterization of a new TEM-derived beta-lactamase produced in a Serratia marcescens strain; Perilli M et al.; A natural TEM variant beta-lactamase was isolated from an epidemic strain of Serratia marcescens . Nucleotide gene sequencing revealed multiple point mutations located in the 42-to-44 tripeptide and positions 145 to 146, 178, and 238 . In addition, a glutamic acid 212 deletion was also found . The purified enzyme was studied from a kinetic point of view, revealing the highest catalytic efficiency (k{cat}/Km) values for ceftazidime and aztreonam compared with the TEM-1 prototype enzyme . The in vitro resistance correlated with kinetic parameters, and the enzyme also mediated resistance to some penicillins and an ampicillin-clavulanic acid combination . The mutational and kinetic changes are discussed in relation to the three-dimensional crystallographic structure of the wild-type TEM-1 enzyme. J Med Microbiol, 1997 Nov, 46(11), 913 - 9 The use of RAPD-PCR as a typing method for Serratia marcescens; Hejazi A et al.; Serratia marcescens has emerged in the last few years as an important nosocomial pathogen . Many methods for typing this organism have been described . In this study the random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was shown to be a convenient typing method for S . marcescens . Different combinations of primers previously used for typing other gram-negative bacilli were assessed . The combination of primer HLWL-74 and 1254 gave distinguishable patterns for different serotypes and proved to be the most satisfactory . By applying this combination to 175 isolates of S . marcescens, which could be classified into 38 groups on the basis of serotyping and phage typing, 73 different RAPD patterns with good reproducibility were obtained . This is, to our knowledge, the first application of the method to a large collection of S . marcescens representing a wide range of serotypes. Pharmazie, 1997 Oct, 52(10), 753 - 8 Synthesis of some biologically active agents derived from thieno{2,3-d}pyrimidine derivatives; Hozien ZA et al.; The key compound 1-amino-8-iminocyclopenta{b}thieno{2,3-d}pyrimidine (5g) was prepared by reaction of 2-amino-3-cyano cyclopenta{b}thiophene (1) with triethyl orthoformate followed by cyclization with hydrazine hydrate in ethanol . Refluxing of 1 with triethyl orthoformate in the presence of acetic anhydride gave an unexpected product 2 . while reaction with aromatic amines gave the condensation products 4a-c . Reaction of 5g with formic acid, other formate derivatives, ethoxymethylenemalononitrile and ethyl ethoxymethylenecyanoacetate gave the same product cyclopentathieno-{2,3-d}-1,2,4-triazolo{3,2-f}pyrimidine 6 . Compound 7 was prepared by different methods . Treatment of 5g with dicarbonyl compounds gave the triazol derivatives 8-11 . Reaction of 5g with phenyl isothiocyanate, carbon disulphide and ethyl chloroformate gave the corresponding derivatives 12-14, respectively . Condensation of 5g with some selected aromatic and heterocyclic aldehydes, acetone, N-acetyl isatin and isatin gave the condensation products 15a-e, 16-18, respectively in good yields . Many of the synthesized compounds were tested in vitro for their inhibitory activity against a variety of bacteria such as: Serratia rhodnii, Bacillus cereus, Staphylococcus citreus and Pseudomonas aeruginosa and fungi such as: Aspergillus flavus, Penicillium chrysogenum and Alternaria alternarta . Some compounds showed modest activity. Adv Perit Dial, 1997, 13, 233 - 6 Persistent exit-site/tunnel infection and subcutaneous cuff removal in PD patients; Suh H et al.; The purpose of our study was to investigate catheter outcome of persistent exit-site/tunnel infections (ESI/TIs) in peritoneal dialysis (PD) patients . The patients underwent removal of subcutaneous cuff due to persistent ESI/TI from January 1989 to December 1996 in a tertiary referral university hospital . Two hundred and twenty-three patients (138 male, 85 female) underwent 244 double-cuff coiled Swan neck catheter implantations surgically . Twenty-nine patients (11.8%) had persistent ESI/TI for more than 6 months with the same organism . Sixteen patients (52%) underwent subcutaneous cuff excision . Thirteen (48%) patients refused and were managed conservatively . Two hundred and forty-three episodes of ESI/TI were observed over 4970 patient-months with a rate of 0.58 episodes/patient/year . Twenty-nine patients (11.8%) had persistent ESI/TI with S . aureus in 19, Pseudomonas aeruginosa in 9 (31%), and Serratia marcescens in one (3%) patient . Fourteen (88%) persistent ESI/TIs resolved after subcutaneous cuff excision . None of the patients with ESI/TI responded to conservative treatment . ESI/TI-related peritonitis decreased from 11 episodes to 5 episodes after cuff excision . In contrast, episodes of peritonitis increased from one to 9 with conservative management during a follow-up of mean 18 months (4-38 months) . Four (31%) catheters were lost in the conservative group, while 3 (19%) were lost after cuff excision . ESI/TI-related peritonitis decreased after subcutaneous cuff excision but increased with conservative management for ESI/TI . ESI/TI resolved in 88% of the patients after cuff excision, while none resolved with conservative treatment. Microbiologia, 1997 Sep, 13(3), 315 - 20 The role of outer membrane in Serratia marcescens intrinsic resistance to antibiotics; Sanchez L et al.; Three different porins from Serratia marcescens were described . They were named Omp1, Omp2 and Omp3 and their molecular weights were 42, 40 and 39 kDa respectively . Omp2 and Omp3 showed osmoregulation and thermoregulation in a similar way to OmpC and OmpF of Escherichia coli . Permeability coefficients of the outer membrane of this species were calculated following the Zimmermann and Rosselet method . P values were similar to those obtained in Escherichia coli, which suggests that the chromosomal beta-lactamase would play a major role in the resistance of Serratia marcescens to beta-lactam antibiotics . Both MIC values and permeabilities were modified by salycilates and acetylsalycilate . Synergism between the outer membrane and the beta-lactamase was also evaluated . When bacteria grew in the presence of a beta-lactam in the medium, the beta-lactamase accounted for most of the resistance. Appl Microbiol Biotechnol, 1997 Sep, 48(3), 317 - 24 Production, purification and characterization of a 50-kDa extracellular metalloprotease from Serratia marcescens; Salamone PR et al.; The extracellular metalloprotease (SMP 6.1) produced by a soil isolate of Serratia marcescens NRRL B-23112 was purified and characterized . SMP 6.1 was purified from the culture supernatant by ammonium sulfate precipitation, acetone fractional precipitation, and preparative isoelectric focusing . SMP 6.1 has a molecular mass of approximately 50,900 Da by sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) . The following substrates were hydrolyzed: casein, bovine serum albumin, and hide powder . SMP 6.1 has the characteristics of a metalloprotease, a pH optimum of 10.0, and a temperature optimum of 42 degrees C . The isoelectric point of the protease is 6.1 . Restoration of proteolytic activity by in-gel renaturation after SDS-PAGE indicates a single polypeptide chain . SMP 6.1 is inhibited by EDTA (9 micrograms/ml) and not inhibited by antipain dihydrochloride (120 micrograms/ml), aprotinin (4 micrograms/ml), bestatin (80 micrograms/ml), chymostatin (50 micrograms/ml), E-64 (20 micrograms/ml), leupeptin (4 micrograms/ml), Pefabloc SC (2000 micrograms/ml), pepstatin (4 micrograms/ml), phosphoramidon (660 micrograms/ml), or phenylmethylsulfonyl fluoride (400 micrograms/ml) . SMP 6.1 retains full activity in the presence of SDS (1% w/v), Tween-20 (1% w/v), Triton X-100 (1% w/v), ethanol (5% v/v), and 2-mercaptoethanol (0.5% v/v) . The extracellular metalloprotease SMP 6.1 differs from the serratiopeptidase (Sigma) produced by S . marcescens ATCC 27117 in the following characteristics: isoelectric point, peptide mapping and nematolytic properties. Infect Control Hosp Epidemiol, 1997 Oct, 18(10), 704 - 9 Serratia marcescens outbreak associated with extrinsic contamination of 1% chlorxylenol soap; Archibald LK et al.; OBJECTIVES: To determine risk factors for Serratia marcescens infection or colonization, and to identify the source of the pathogen and factors facilitating its persistence in a neonatal intensive-care unit (NICU) during an outbreak . DESIGN: Retrospective case-control study; review of NICU infection control policies, soap use, and handwashing practices among healthcare workers (HCWs); and selected environmental cultures . SETTING: A university-affiliated tertiary-care hospital NICU . PATIENTS: All NICU infants with at least one positive culture for S marcescens during August 1994 to October 1995 . Infants who did not develop S marcescens infection or colonization were selected randomly as controls . RESULTS: Thirty-two patients met the case definition . On multivariate analysis, independent risk factors for S marcescens infection or colonization were having very low birth weight (< 1,500 g), a patent ductus arteriosus, a mother with chorioamnionitis, or exposure to a single HCW . During January to July 1995, NICU HCWs carried their own bottles of 1% chlorxylenol soap, which often were left standing inverted in the NICU sink and work areas . Cultures of 16 (31%) of 52 samples of soap and 1 (8%) of 13 sinks yielded S marcescens . The 16 samples of soap all came from opened 4-oz bottles carried by HCWs . DNA banding patterns of case infant, HCW soap bottle, and sink isolates were identical . CONCLUSIONS: Extrinsically contaminated soap contributed to an outbreak of S marcescens infection . Very-low-birth-weight infants with multiple invasive procedures and exposures to certain HCWs were at greatest risk of S marcescens infection or colonization. J Biochem (Tokyo), 1997 Sep, 122(3), 601 - 5 Prolyl aminopeptidase from Serratia marcescens: cloning of the enzyme gene and crystallization of the expressed enzyme; Kabashima T et al.; We cloned and sequenced the Serratia marcescens prolyl aminopeptidase (SPAP) gene . Nucleotide sequence analysis revealed an open reading frame of 951 bp, encoding a protein of 317 amino acids with a predicted molecular weight of 36,083 . The expressed enzyme was purified about 90-fold on columns of Toyopearl HW65C and DEAE-Toyopearl, with an activity recovery of 30% . The apparent molecular weight of the purified enzyme was 36,000 and 38,000 as estimated by SDS-PAGE and gel filtration, respectively . The enzyme was not inhibited by diisopropyl phosphofluoridate (DFP) or phenylmethylsulfonyl fluoride (PMSF), but was markedly inhibited by 3,4-dichloroisocoumarin (DCIC) . Crystals of the enzyme were grown by the hanging drop vapor diffusion method using PEG6000 as a precipitant at pH 6.5 . The crystals are tetragonal with cell dimensions a= b =65.6 A, and c=169.8 A, a space group P4(1)2(1)2 or P4(3)2(1)2, and probably contain one monomer in the asymmetric unit . They diffract to at least 2.22 A resolution. Arch Insect Biochem Physiol, 1997, 36(3), 223 - 7 Effect of demethylation on the chitinase inhibitory activity of allosamidin; Spindler KD et al.; Removal of a methyl group of the allosamizoline moiety of allosamidin decreases the inhibitory effect on family 18 chitinases from three different species (a bacterium, Serratia marcescens, a crustacean, Artemia salina, and an insect cell line, Chironomus tentans) . Loss of a second methyl group weakens enzyme inhibition further . This is in agreement with the highly conserved catalytic centre of these enzymes. J Bacteriol, 1997 Oct, 179(20), 6522 - 4 The Serratia marcescens NucE protein functions as a holin in Escherichia coli; Berkmen M et al.; The recently discovered nucC locus of Serratia marcescens encodes the cryptic prophage genes nucE, nucD, and nucC . NucC is required for expression of the S . marcescens nuclease and functions as a transcriptional activator of the nuclease gene, nucA . NucE and NucD are dispensable for nuclease expression but were proposed to allow for secretion of the nuclease by Escherichia coli . Here, we show (i) that the NucE protein is membrane bound, (ii) that it can complement the lambda S holin, (iii) that it can be triggered by potassium cyanide, (iv) that it is detrimental to cell viability, and (v) that the concomitant expression of nucE and nucD results in cell lysis . Apparently NucE and NucD function as a holin and an endolysin, respectively . This suggests that their roles in nuclease secretion by E . coli are indirect, possibly through directed cell lysis. Microbiology, 1997 Aug, 143 ( Pt 8), 2797 - 806 Molecular characterization of the Serratia marcescens OmpF porin, and analysis of S . marcescens OmpF and OmpC osmoregulation; Hutsul JA et al.; Serratia marcescens is a nosocomial pathogen with a high incidence of beta-lactam resistance . Reduced amounts of outer-membrane porins have been correlated with increased resistance to beta-lactams but only one porin, OmpC, has been characterized at the molecular level . In this study we present the molecular characterization of a second porin, OmpF, and an analysis of the expression of S . marcescens porins in response to various environmental changes . Two porins were isolated from the outer membrane using urea-SDS-PAGE and the relative amounts were shown to be influenced by the osmolarity of the medium and the presence of salicylate . From a S . marcescens genomic DNA library an 8 kb EcoRI fragment was isolated that hybridized with an oligonucleotide encoding the published N-terminal amino acid sequence of the S . marcescens 41 kDa porin . A 41 kDa protein was detected in the outer membrane of Escherichia coli NM522 carrying the cloned S . marcescens DNA . The cloned gene was sequenced and shown to code for a protein that shared 60-70% identity with other known OmpF and OmpC sequences . The upstream DNA sequence of the S . marcescens gene was similar to the corresponding E . coli ompF sequence; however, a regulatory element important in repression of E . coli ompF at high osmolarity was absent . The cloned S . marcescens OmpF in E . coli increased in expression in conditions of high osmolarity . The potential involvement of micF in the observed osmoregulation of S . marcescens porins is discussed. J Bacteriol, 1997 Aug, 179(15), 4919 - 28 Colicin U, a novel colicin produced by Shigella boydii; Smajs D et al.; A novel colicin, designated colicin U, was found in two Shigella boydii strains of serovars 1 and 8 . Colicin U was active against bacterial strains of the genera Escherichia and Shigella . Plasmid pColU (7.3 kb) of the colicinogenic strain S . boydii M592 (serovar 8) was sequenced, and three colicin genes were identified . The colicin U activity gene, cua, encodes a protein of 619 amino acids (Mr, 66,289); the immunity gene, cui, encodes a protein of 174 amino acids (Mr, 20,688); and the lytic protein gene, cul, encodes a polypeptide of 45 amino acids (Mr, 4,672) . Colicin U displays sequence similarities to various colicins . The N-terminal sequence of 130 amino acids has 54% identity to the N-terminal sequence of bacteriocin 28b produced by Serratia marcescens . Furthermore, the N-terminal 36 amino acids have striking sequence identity (83%) to colicin A . Although the C-terminal pore-forming sequence of colicin U shows the highest degree of identity (73%) to the pore-forming C-terminal sequence of colicin B, the immunity protein, which interacts with the same region, displays a higher degree of sequence similarity to the immunity protein of colicin A (45%) than to the immunity protein of colicin B (30.5%) . Immunity specificity is probably conferred by a short sequence from residues 571 to residue 599 of colicin U; this sequence is not similar to that of colicin B . We showed that binding of colicin U to sensitive cells is mediated by the OmpA protein, the OmpF porin, and core lipopolysaccharide . Uptake of colicin U was dependent on the TolA, -B, -Q, and -R proteins . pColU is homologous to plasmid pSB41 (4.1 kb) except for the colicin genes on pColU . pSB41 and pColU coexist in S . boydii strains and can be cotransformed into Escherichia coli, and both plasmids are homologous to pColE1. FEBS Lett, 1997 Jul 21, 412(1), 217 - 22 Three-dimensional structure of Serratia marcescens nuclease at 1.7 A resolution and mechanism of its action; Lunin VY et al.; The three-dimensional crystal structure of Serratia marcescens (Sm) nuclease has been refined at 1.7 A resolution to the R-factor of 17.3% and R-free of 22.2% . The final model consists of 3678 non-hydrogen atoms and 443 water molecules . The analysis of the secondary and the tertiary structures of the Sm nuclease suggests a topology which reveals essential inner symmetry in all the three layers forming the monomer . We propose the plausible mechanism of its action based on a concerted participation of the catalytically important amino acid residues of the enzyme active site. FEMS Microbiol Lett, 1997 Jun 15, 151(2), 197 - 204 Isolation and characterization of the 54-kDa and 22-kDa chitinase genes of Serratia marcescens KCTC2172; Gal SW et al.; A DNA fragment (pCHI5422) containing two genes encoding a 54-kD and a 22-kDa chitinase was isolated from a cosmid DNA library of Serratia marcescens KCTC2172 . The complete nucleotide sequence of pCHI5422 consisting of 4581 bp was determined . The nucleotide sequence of the 22-kDa chitinase consists of 681 bp of open reading frame encoding 227 amino acids and is located 1422 bp downstream of the translation termination codon of the 54-kDa chitinase sequence . The 54-kDa chitinase gene consisted of 1497 bp in a single open reading frame encoding 499 amino acids . The genes encoding the 54-kDa and 22-kDa chitinase were separately subcloned in Escherichia coli and the individual chitinases were expressed and purified from the culture broth using chitin affinity chromatography . When chitohexaose was used as substrate, the major product of the enzymatic reaction of both the 54-kDa and 22-kDa chitinases was a (GlcNAc)2 dimer with a minor amount of monomer . The specific activity of the 54-kDa and 22-kDa chitinases were 300 microM (min)-1 mg-1 and 17 microM (min)-1 mg-1 on the natural swollen chitin, respectively. Biochemistry, 1997 Jun 10, 36(23), 7050 - 7 Purification and characterization of an extracellular heme-binding protein, HasA, involved in heme iron acquisition; Izadi N et al.; Many bacterial hemoproteins involved in heme acquisition have been isolated recently, comprising outer membrane receptors and extracellular heme-binding protein . The mechanisms by which these proteins extract heme have not been described up to now . One such protein, HasA, which can bind free heme as well as capture it from hemoglobin, is secreted by the Gram-negative bacteria Serratia marcescens under iron deficiency conditions . The fact that HasA does not present sequence similarities with other known hemoproteins suggests that it possesses a new type of heme binding site . This work describes the main physicochemical properties of HasA, essential for understanding its function . HasA is a monomer of 19 kDa that binds one b heme per molecule with high affinity . The electron paramagnetic resonance spectra indicate that the heme iron is in a low-spin ferric state and that the two iron axial ligands are His and His- . The low oxidation-reduction potential value (-550 mV vs standard hydrogen electrode) of the heme bound to HasA suggests that heme could be exposed to the solvent . According to circular dichroism data, the binding of heme does not seem to modify the conformation of HasA. Gene Ther, 1997 Jun, 4(6), 593 - 9 Antiretroviral effect of a gag-RNase HI fusion gene; Schumann G et al.; We have previously shown that a molecule consisting of a fusion of a Ca(2+)-dependent nuclease (from Staphylococcus aureus) to a retroviral coat protein specifies a potent antiviral specific for that retrovirus . Genes specifying such fusion proteins can be delivered to virus-susceptible cells, providing an antiviral gene therapy aimed at limiting virus spread . We report here the results of experiments to vary the nuclease moiety of such fusion proteins . We found that one nuclease . Serratia marcescens nuclease, was extremely toxic to host cells and hence not likely to be useful for therapeutic purposes . A second nuclease, Escherichia coli RNase Hl was found to be nontoxic and highly effective against a murine leukemia virus when it was fused to the leukemia virus coat protein . The fusion protein was enzymatically active and stably expressed, without apparent toxicity to host cells . Reduction in infectious virus output was as high as 97-99% . These studies provide a model system for the development of gene therapeutic agents aimed at combating retroviral infections in vivo. Nippon Kyobu Geka Gakkai Zasshi, 1997 Jun, 45(6), 860 - 4 {Serratia marcescens prosthetic mitral valve endocarditis associated with hemolytic anemia}; Kochi K et al.; A 57-year-old female who had been performed mitral valve replacement (MVR) using 31 mm prosthetic valve 32 months before entered the hospital for the evaluation of long standing severe hemolytic anemia without infectious sign . Transesophageal echocardiogram revealed a moderate sized vegetation on the atrial site of the prosthetic valve . The size and number of the vegetation were increased after deterioration of infectious illness . Blood culture grew serratia marcessans and alpha-hemolytic Streptococcus . Re-MVR was carried out with the diagnosis of prosthetic valve endocarditis (PVE) . As the symptom of PVE, hemolytic anemia without infectious sign is a rare condition . TEE is an useful method to make diagnosis of PVE by detecting the vegetations and evaluating their change of size and methods and to evaluate the effectiveness of the treatment. J Bacteriol, 1997 Jun, 179(11), 3572 - 9 A new type of hemophore-dependent heme acquisition system of Serratia marcescens reconstituted in Escherichia coli; Ghigo JM et al.; The utilization by Serratia marcescens of heme bound to hemoglobin requires HasA, an extracellular heme-binding protein . This unique heme acquisition system was studied in an Escherichia coli hemA mutant that was a heme auxotroph . We identified a 92-kDa iron-regulated S . marcescens outer membrane protein, HasR, which alone enabled the E . coli hemA mutant to grow on heme or hemoglobin as a porphyrin source . The concomitant secretion of HasA by the HasR-producing hemA mutant greatly facilitates the acquisition of heme from hemoglobin . This is the first report of a synergy between an outer membrane protein and an extracellular heme-binding protein, HasA, acting as a heme carrier, which we termed a hemophore. J Mol Biol, 1997 May 9, 268(3), 589 - 98 The nuiA gene from Anabaena sp . encoding an inhibitor of the NucA sugar-non-specific nuclease; Muro-Pastor AM et al.; Many filamentous, heterocyst-forming cyanobacteria express a sugar-non-specific nuclease of about 29 kDa that can be detected in DNA-containing SDS-PAGE gels . The nucA gene encoding this nuclease has previously been cloned from Anabaena sp . PCC 7120, sequenced and expressed in Escherichia coli . The NucA protein bears a putative signal peptide close to its N-terminal end and, in Anabaena cultures, is present in both the cells and the extracellular medium . Cell-free extracts of different cyanobacteria producing NucA-like nucleases exhibited an inhibitory activity on NucA . In Anabaena sp . PCC 7120, this inhibition was exerted by protein(s) or protein-containing molecule(s) that were heat resistant . Immediately downstream from the nucA gene, in the complementary strand, we have identified an open reading frame composed of 135 codons, that we have named nuiA, whose expression in E . coli conferred heat-resistant NucA-inhibitory activity to cell-free extracts . The NuiA protein was purified to homogeneity, and purified NuiA inhibited the nuclease activity of NucA . Sequences hybridizing with the nuiA gene have been found in all the tested cyanobacterial strains that express a NucA-like nuclease . Whereas the NucA protein is homologous to endonuclease G from vertebrates and to nucleases from Serratia marcescens and yeast, no protein homologous to NuiA was found in the available databases . Therefore, nuiA represents a novel gene encoding a nuclease inhibitor. Ophthalmologe, 1997 May, 94(5), 311 - 6 {Contact lenses . Infections and hygiene}; Brewitt H; BACKGROUND: Contact lens wearers are subject to increased risk of infection, and an attempt was made to determine which factors cause the overproportional risk of infection? PATIENTS: The aim of this paper is to explain with appropriate bibliographic support why people who wear contact lenses are at risk of infection . RESULTS: The relative risk of keratitis is a function of the lens material and the wearing time of the contact lenses . Extended wear of hydrogel lenses is associated with an overproportional risk of infection . According to the literature, the frequency of complications in contact lens wearers generally is the result of poor hygiene in 66% of the cases . The general lack of hygiene among contact lens wearers must, therefore, be regarded as one cause among pathophysiological mechanisms of the eye . The microbial spectrum favors gram-negative bacteria living in a wet environment such as Pseudomonas, Serratia and parasites like Acanthamoeba . CONCLUSION: The specific spectrum of pathogens and new problem organisms not only challenge the fitter but also the manufacturers to adapt hygiene (sanitary) measures and products to the new development . Disposable contact lens systems are the first step, but they do not solve all the problems of contact lens wearers . Therefore, the importance of contact lens hygiene must be especially emphasized when the ophthalmologist is giving instructions to the patient . On the other hand, hygiene should also not be neglected by the contact lens fitters since it is part of the whole problem. Aust N Z J Ophthalmol, 1997 May, 25 Suppl 1, S39 - 41 Adhesion and growth of Serratia marcescens on artificial closed eye tears soaked hydrogel contact lenses; Hume EB et al.; The adhesion to hydrogel contact lenses and growth of Serratia marcescens on artificial tear fluid (ATF) soaked lenses was investigated . Results indicated that a corneal ulcer isolate adhered more avidly to lenses; ATF increased adhesion for all strains tested . The contact lens induced acute red eye (CLARE) isolate adhered poorly, however, it grew to a larger extent on ATF-coated lenses . The ability of the corneal ulcer isolate to adhere to lenses may be an important factor in its pathogenicity whereas the ability of the CLARE isolate to grow on the lens in the presence of antimicrobial tear proteins may be important in the development of inflammation. Biochemistry, 1997 Apr 22, 36(16), 4949 - 58 Kinetic characterization of the serralysins: a divergent catalytic mechanism pertaining to astacin-type metalloproteases; Mock WL et al.; Substrates HO2CCH2CH2CO- and HOCH2CHOHCHOHCO-Phe-Leu-Ala-5-nitro-2-pyridinamide are cleaved efficiently at the acylarenamide linkage, with a convenient spectrophotometric assay, by the Serratia and Pseudomonas approximately 50-kDa extracellular metalloproteases (serralysins) . The pH range of catalytic activity extends uniformly from 4 to greater than 10 (k(cat)/Km approximately 10(3) s(-1) M(-1), similar profile for k(cat)) . Substrate analogue hydroxamic acid Cbz-Leu-Ala-NHOH competitively inhibits serralysin (Ki 0.04 mM), with a pH dependence indicating that either a displaced metal-bound H2O or a similarly motile enzymic phenol residue (Tyr216) that is crystallographically found ligated to the active-site Zn2+ of the uncomplexed enzyme must have a pKa of approximately 5 . A chemical catalytic mechanism of proteolysis consistent with the kinetic data is proposed, in which Tyr216-ArO-, in the course of being released from the active-site metal ion, deprotonates a water molecule attacking the Zn2+-activated substrate linkage, leading to a metal-coordinated tetrahedral oxyanion adduct that subsequently fragments. Biopolymers, 1997 Apr 5, 41(4), 443 - 50 Simulation of electrostatic and hydrodynamic properties of Serratia endonuclease; Antosiewicz J et al.; We analyze the electrostatic and hydrodynamic properties of a nuclease from the pathogenic gram-negative bacterium Serratia marcescens using finite-difference Poisson-Boltzmann methods for electrostatic calculations and a bead-model approach for diffusion coefficient calculations . Electrostatic properties are analyzed for the enzyme in monomeric and dimeric forms and also in the context of DNA binding by the nuclease . Our preliminary results show that binding of a double-stranded DNA dodecamer by nuclease causes an overall shift in the charge of the protein by approximately three units of elementary charge per monomer, resulting in a positively charged protein at physiologic pH . In these calculations, the free enzyme was found to have a negative (-1 e) charge per monomer at pH 7 . The most dramatic shift in pKa involves His 89 whose pKa increases by three pH units upon DNA binding . This shift leads to a protonated residue at pH 7, in contrast to the unprotonated form in the free enzyme . DNA binding also leads to a decrease in the energetic distances between the most stable protonation states of the enzyme . Dimerization has no significant effect on the electrostatic properties of each of the monomers for both free enzyme and that bound to DNA . Results of hydrodynamic calculations are consistent with the dimeric form of the enzyme in solution . The computed translational diffusion coefficient for the dimer model of the enzyme is in very good agreement with measurements from light scattering experiments . Preliminary electrooptical calculations indicate that the dimer should possess a large dipole moment (approximately 600 Debye units) as well as substantial optical anisotropy (limiting reduced linear electric dichroism of about 0.3) . Therefore, this system may serve as a good model for investigation of electric and hydrodynamic properties by relaxation electrooptical experiments. J Infect Dis, 1997 Apr, 175(4), 992 - 5 Postoperative Serratia marcescens wound infections traced to an out-of-hospital source; Passaro DJ et al.; From 25 August to 28 September 1994, 7 cardiovascular surgery (CVS) patients at a California hospital acquired postoperative Serratia marcescens infections, and 1 died . To identify the outbreak source, a cohort study was done of all 55 adults who underwent CVS at the hospital during the outbreak . Specimens from the hospital environment and from hands of selected staff were cultured . S . marcescens isolates were compared using restriction-endonuclease analysis and pulsed-field gel electrophoresis . Several risk factors for S . marcescens infection were identified, but hospital and hand cultures were negative . In October, a patient exposed to scrub nurse A (who wore artificial fingernails) and to another nurse-but not to other identified risk factors-became infected with the outbreak strain . Subsequent cultures from nurse A's home identified the strain in a jar of exfoliant cream . Removal of the cream ended the outbreak . S . marcescens does not normally colonize human skin, but artificial nails may have facilitated transmission via nurse A's hands. Curr Microbiol, 1997 Apr, 34(4), 212 - 5 Effect of bacteria on survival and growth of Acanthamoeba castellanii; Wang X et al.; The growth and survival of Acanthamoeba castellanii in the presence of Gram-negative bacteria such as Pseudomonas aeruginosa, Escherichia coli, Serratia marcescens, and Stenotrophomonas maltophilia varied with the densities and species of bacteria . All species of bacteria suspended in a buffered saline at densities of 10(5) to 10(6)/ml supported the growth and survival of 10(6)/ml trophozoites of Acanthamoeba castellanii in a buffered saline solution . At densities of bacteria to amoebae of 100:1 or greater, growth and survival of A . castellanii were suppressed, particularly by P . aeruginosa . In an enrichment medium, the rapid growth of most co-inoculated bacteria inhibited the growth and survival of the amoeba. Biochemistry, 1997 Mar 18, 36(11), 3126 - 32 Conversion of the allosteric regulatory patterns of aspartate transcarbamoylase by exchange of a single beta-strand between diverged regulatory chains; Liu L et al.; Although structurally very similar, the aspartate transcarbamoylases (ATCase) of Serratia marcescens and Escherichia coli differ in both regulatory and catalytic characteristics . Most notably, CTP stimulates the catalytic activity of the S . marcescens ATCase and CTP/UTP inhibitory synergism has been lost . These allosteric characteristics contradict the traditional logic developed from the E . coli enzyme in which CTP and UTP function together as end products of the pyrimidine pathway to allosterically control the catalytic activity . In this study, five divergent residues (r93-r97) of the regulatory polypeptide of the S . marcescens enzyme have been replaced with their E . coli counterparts . These residues correspond to the S5' beta-strand of the allosteric effector binding domain at the junction of the allosteric and zinc domains of the regulatory polypeptide . In spite of the fact that the chimeric ATCase (SM:rS5'ec) retained 455 out of 460 amino acids of the S . marcescens enzyme, it possessed characteristics similar to those of the E . coli enzyme: (1) the {Asp}0.5 decreased from 40 to 5 mM; (2) ATP activation of the enzyme was greatly reduced; (3) CTP was converted from a strong activator to a strong inhibitor; and (4) the synergistic inhibition by CTP and UTP was restored . The S5' beta-strand is located at the outer surface of a five-stranded beta-sheet of the allosteric domain, providing a potential structural mechanism defining the allostery of this enzyme. J Am Vet Med Assoc, 1997 Mar 15, 210(6), 794 - 8 Serratia marcescens contamination of feline whole blood in a hospital blood bank; Hohenhaus AE et al.; During a 7-month period, 29 units of feline whole blood in a hospital blood bank were confirmed, and 2 units were suspected, to be contaminated with Serratia marcescens . An investigation of the outbreak identified S marcescens in a jar of alcohol-soaked cotton balls and in a bag of saline solution used during venipuncture . Fifteen of the contaminated units were administered to 14 cats, and 6 of the 14 developed clinical signs of a transfusion reaction . The most common sign was vomiting; 4 cats died . The report underscores the importance of using aseptic techniques during collection of blood for transfusion and of thoroughly investigating any transfusion reaction. Anal Biochem, 1997 Mar 15, 246(2), 171 - 5 Serratia liquefaciens as a new host superior for overproduction and purification using the N-acetylneuraminate lyase gene of Escherichia coli; Yamamoto K et al.; Serratia liquefaciens was screened as a host strain for effective gene expression and easy purification of the target protein . A model gene, N-acetylneuraminate lyase gene (nanA), fused with the promoter region of Escherichia coli lac operon successfully overproduced the protein independently from the inducer . Since S . liquefaciens grew at lower temperature than E . coli and its proteins were more heat sensitive than those of E . coli, simple incubation at 60 degrees C could inactivate most enzymes but the nanA protein . Subsequent column works for purification, then, became simple and rapid. Int J Food Microbiol, 1997 Mar 3, 34(3), 259 - 66 Characterisation of virulence factors of Serratia strains isolated from foods; Singh BR et al.; Out of 21 Serratia strains isolated from fresh juice and fish samples, five S . marcescens and two S . rubidaea caused lethality in mice on parenteral inoculation, but none through oral feeding . Three S . marcescens and one S . rubidaea produced heat-labile enterotoxin, detectible with the rabbit ligated ileal loop test, the mouse foot pad test and the vasopermeability factor test . Cell free culture filtrate (CFCF) of two enterotoxigenic S . mearcescens strains induced cytotoxic effect on a monolayer of Vero-cells, but CFCF of other enterotoxigenic strains could only induce cytotonic changes in Vero-cells . All strains possessed fimbriae type 3 while, only pathogenic strains had type 4 fimbriae and a colonization factor . All pathogenic Serratia strains were agglutinated at comparatively lower salt concentrations than non pathogenic strains (< 1.3 M), and had multiple drug resistance . Their public health significance is also discussed. J Med Microbiol, 1997 Mar, 46(3), 251 - 5 Pre-treatment with Concanavalin-A increases resistance of mice to peritoneal infection by Serratia marcescens; Arraes SM et al.; Mice pre-treated with Concanavalin-A largely survived an intra-peritoneal inoculum of 2 x 10(7) Serratia marcescens, whereas all control mice died within 15 h of inoculation . A subpopulation of peritoneal macrophages from Con-A pre-treated mice was able to phagocytose the bacteria in vitro (6.7 SEM 1.2% phagocytosing cells) and in vivo (16.9 SEM 2.1%), whereas control phagocytes did not phagocytose S . marcescens . The survival of Con-A pre-treated mice allowed their immunisation with living bacteria, and the antiserum thus produced increased the phagocytosis of S . marcescens in vitro . Control mice largely survived an inoculum of S . marcescens suspended in 50% immune serum, although the bacteria were resistant to the bactericidal activity of that serum . These results suggest that, in contrast to the delayed humoral protection afforded by immunisation, phagocytosis by phagocytes activated by Con-A conferred early protection to mice against experimental infection by S . marcescens. Biosci Biotechnol Biochem, 1997 Mar, 61(3), 561 - 2 Isolation of propioxatin A from Actinosynnema sp . SI-23 during a screening for Serratia piscatorum metalloproteinase inhibitors; Murao S et al.; An inhibitor of Serratia metalloproteinase was found in the cultured broth of strain SI-23, which was identified to be Actinosynnema sp . The inhibitor had a potent inhibitory effect on Serratia metalloproteinase and a weak effect on thermolysin, but no effect on other groups of proteinases . The structure of the inhibitor was deduced to be propioxatin A, reported as an enkephalinase B inhibitor. Ophthalmic Surg Lasers, 1997 Mar, 28(3), 195 - 200 Endophthalmitis caused by Serratia marcescens; Cohen SM et al.; BACKGROUND AND OBJECTIVE: To describe the clinical features and treatment outcomes of 10 patients with culture-proven Serratia marcescens endophthalmitis . PATIENTS AND METHODS: Records from the microbiology laboratory for the period from January 1980 through June 1993 were reviewed . Ten patients were identified who had positive anterior chamber or vitreous cultures and clinical signs of endophthalmitis . The medical records for these 10 patients were reviewed, and the patients were contacted for reexamination when possible . RESULTS: All 10 cases of S . marcescens endophthalmitis occurred after ocular surgery . Eight eyes received intraocular antibiotics and 2 eyes were primarily enucleated or eviscerated . All organisms were sensitive to aminoglycosides and to ceftazidime . Repeat vitreous cultures were positive in 5 cases despite appropriate initial therapy with intravitreal and intravenous antibiotics . Final visual acuity was 20/400 or better in 4 of 10 eyes . A total of 4 eyes were enucleated or eviscerated at final follow-up . Eyes with light perception or better visual acuity had a mean follow-up of 23 months . CONCLUSION: S . marcescens can cause persistent endophthalmitis despite appropriate intravitreal and systemic antibiotic therapy . Eyes with S . marcescens endophthalmitis have a poor visual prognosis. J Biol Chem, 1997 Feb 28, 272(9), 6059 - 66 Activation of human matrix metalloproteinases by various bacterial proteinases; Okamoto T et al.; Matrix metalloproteinases (MMPs) are zinc-containing proteinases that participate in tissue remodeling under physiological and pathological conditions . To test the involvement of bacterial proteinases in tissue injury during bacterial infections, we investigated the activation potential of various bacterial proteinases against precursors of MMPs (proMMPs) purified from human neutrophils (proMMP-8 and -9) and from human fibrosarcoma cells (proMMP-1) . Each proMMP was subjected to treatment with a series of bacterial proteinases at molar ratios of 0.01-0.1 (bacterial proteinase to proMMP), and activities of MMPs generated were determined . Among six different bacterial proteinases, thermolysin family enzymes (family M4) such as Pseudomonas aeruginosa elastase, Vibrio cholerae proteinase, and thermolysin strongly activated all three proMMPs via limited proteolysis to generate active forms of the MMPs . N-terminal sequence analysis of the active MMPs revealed that cleavage occurred at the Val82-Leu83 and Thr90-Phe91 bonds of proMMP-1 and proMMP-9, respectively, which are located near the N terminus of the catalytic domain of MMPs . In contrast, Serratia 56-kDa proteinase and Pseudomonas alkaline proteinase, both of which are classified as members of the serralysin subfamily of zinc metalloproteinases (family M10), and Serratia 73-kDa thiol proteinase did not evidence proteolytic processing or activation of proMMP-1, -8, and -9 under these experimental conditions . These results indicate that bacterial proteinases may play an important role in tissue destruction and disintegration of extracellular matrix at the site of infections. Burns, 1997 Feb, 23(1), 15 - 8 Containment of a multiresistant Serratia marcescens outbreak; Edgar P et al.; A 3-year-old male from Bolivia who sustained a full-thickness 80 per cent TBSA burn complicated by smoke inhalation on the 28 March 1995 was admitted to our burn centre on 6 April 1995 . On 11 April the patient's wounds were colonized with a Serratia marcescens sensitive only to ciprofloxacin and imipenem . Sputum cultures revealed the same phenotypic S . marcescens . Two patients who were admitted days later had the same phenotypic S . marcescens . Their TBSA burns ranged from 54 to 80 per cent . Both were injured in early April . Sputum and wound cultures were also positive for S . marcescens . Precautionary measures were instituted immediately . All potential reservoirs were cultured . Cultures were negative for S . marcescens . Patient therapy was maintained via strict isolation . The first patient died on 17 May . The two remaining patients survived and were discharged colonized with S . marcescens . However, the biotype of the initial S . marcescens was different from the latter two . Early recognition of a multiresistant S . marcescens resulted in negating the spread of this agent to other patients. Ann Allergy Asthma Immunol, 1997 Feb, 78(2), 225 - 9 New occupational allergen in a pharmaceutical industry: serratial peptidase and lysozyme chloride; Park HS et al.; BACKGROUND: Serratial peptidase and lysozyme are often used as anti-inflammatory agents . There have been very few documented cases of occupational allergy caused by these substances . We report a case of a pharmaceutical industry worker who developed occupational asthma and rhinitis caused by both serratial peptidase and lysozyme chloride . OBJECTIVE: It is important to alert physicians to the possibility of occupational asthma when dealing with workers in the pharmaceutical industry . METHOD AND RESULT: The patient had strong positive responses to peptidase and lysozyme extracts on skin-prick tests . Bronchoprovocation tests showed a dual asthmatic response to peptidase and an early asthmatic response to lysozyme . Serum specific IgE antibodies to peptidase and lysozyme were detected by enzyme-linked immunosorbent assay (ELISA) . In order to further characterize the allergenic component of these extracts, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and electroblotting studies were also performed . More than ten components ranging form 7.3 to 83.1 kD were found in peptidase extracts, and two IgE binding components (67, 10.9 kD) were detected within the lysozyme extracts . CONCLUSION: These findings suggest that inhalation of peptidase and lysozyme can induce IgE-mediated bronchoconstrictions in an exposed worker. J Bacteriol, 1997 Feb, 179(3), 677 - 83 Secretion of nuclease across the outer membrane of Serratia marcescens and its energy requirements; Suh Y et al.; Extracellular secretion of Serratia marcescens nuclease occurs as a two-step process via a periplasmic intermediate . Unlike other extracellular proteins secreted by gram-negative bacteria by the general secretory pathway, nuclease accumulates in the periplasm in its active form for an unusually long time before its export into the growth medium . The energy requirements for extracellular secretion of nuclease from the periplasm were investigated . Our results suggest that the second step of secretion across the outer membrane is dependent upon the external pH; acidic pH effectively but reversibly blocks extracellular secretion . However, electrochemical proton gradient, and possibly ATP hydrolysis, are not required for this step . We suggest that nuclease uses a novel mechanism for the second step of secretion in S . marcescens. J Biol Chem, 1997 Jan 17, 272(3), 1997 - 2004 Binding of thrombin to the G-protein-linked receptor, and not to glycoprotein Ib, precedes thrombin-mediated platelet activation; Liu L et al.; The roles of the G-protein-linked thrombin receptor and platelet glycoprotein Ib (GPIb) as alpha-thrombin-binding sites on platelets remain controversial . alpha-Thrombin has been proposed to bind to both GPIb and the hirudin-like domain of the G-protein-linked receptor (from which it cleaves the NH2-terminal extracellular domain to release a 41-mer peptide (TR-(1-41), where TR is alpha-thrombin receptor)) to initiate platelet activation . Using affinity-purified rabbit anti-human TR-(1-41) IgG and immunoblotting, we demonstrated TR-(1-41) release from platelets suspended in Tyrode's buffer containing 2 mM CaCl2 and incubated with >/=0.5 nM alpha-thrombin for 10-60 s at 37 degrees C . As quantified by enzyme-linked immunosorbent assay, 0.32-0.59 nM TR-(1-41) was released from washed platelets (5 x 10(11) platelets/liter) after their incubation with 10 nM alpha-thrombin for 10 s . Parallel binding of alpha-thrombin to and activation of the platelets were confirmed by flow cytometry . A monoclonal antibody against the hirudin-like domain of the G-protein-linked receptor abrogated alpha-thrombin binding to platelets, cleavage of TR-(1-41), and platelet activation by </=1.0 nM (but not 10 nM) alpha-thrombin . Proteolysis of platelet GPIb with Serratia marcescens protease or O-sialoglycoprotein endopeptidase had no effect on alpha-thrombin binding to platelets or their subsequent activation . In contrast, chymotrypsin, which cleaves both GPIb and the G-protein-linked receptor, abrogated alpha-thrombin binding to platelets, TR-(1-41) release, and platelet activation . Furthermore, monoclonal antibodies directed against the reported alpha-thrombin-binding site on GPIb inhibited neither alpha-thrombin binding to nor activation of the platelets . Thus, alpha-thrombin binds to and cleaves the G-protein-linked receptor when it activates platelets, and GPIb does not appear to serve as an important binding site when alpha-thrombin activates platelets. Exp Eye Res, 1997 Jan, 64(1), 3 - 9 Lipopolysaccharide induced acute red eye and corneal ulcers; Schultz CL et al.; Using a new animal model, the aims of this study were to assess the role played by purified lipopolysaccharide (LPS) and neutrophils in the pathogenesis of acute red-eye reactions (ARE) and corneal ulcers . In addition, IL-1 alpha was assessed for its implications in the formation of corneal ulcers . Following corneal abrasion, eyes of rabbits underwent single or double exposures to various doses of LPS from Pseudomonas aeruginosa or Serratia marcescens . This protocol induced ARE symptoms, and their severity depended on the dosage, number of LPS exposures, and type of LPS used (LPS from S . marcescens showing highest virulence) . Corneal ulcers were induced by delivering a high dose of Serratia LPS (100 micrograms) followed by a low dose (10 micrograms) . Histopathological examination revealed that both ARE and corneal ulceration were associated with prominent neutrophil infiltration . In addition, many lymphocytes and other monocytic cells infiltrated ulcerated ocular tissue . Tear fluids obtained from ulcerated eyes contained high concentrations of a protein recognized by anti-rabbit IL-1 alpha antibodies as demonstrated by immunoblotting studies . The results indicate that LPS can induce ARE and corneal ulceration in the absence of any live bacteria . Moreover, the findings implicate the accumulation of neutrophils and IL-1 alpha-related proteins in the pathogenesis of ARE and corneal ulcers. Microbiol Immunol, 1997, 41(1), 27 - 32 Optical configuration analysis of hydroxy fatty acids in bacterial lipids by chiral column high-performance liquid chromatography; Nakagawa Y et al.; Through the adoption of a chiral stationary phase in high-performance liquid chromatography and a simple derivatization method for hydroxy fatty acids, it became easy to separate and identify the optical isomers of 2- and 3-hydroxy fatty acids composing several kinds of microbial lipids . The 2- and 3-hydroxy fatty acids were converted with dinitrophenyl isocyanate to their 3,5-dinitrophenyl urethane derivatives (DU-derivatives), which were analyzable by HPLC using a chiral column . By varying the composition of an eluent, separation of the DU-derivatives of hydroxy fatty acids differing in optical configuration, chain length and position of hydroxyl group was achieved . The general elution orders of these DU-derivatives were determined with authentic 2- and 3-hydroxy fatty acids . Small amounts (approximately 300 micrograms) of ornithine-containing lipids isolated from the Serratia marcescens strains were examined by this method to identify 3-hydroxy fatty acids of the lipids as D isomers. Insect Biochem Mol Biol, 1997 Jan, 27(1), 1 - 7 The plasma protein scolexin from Manduca sexta is induced by baculovirus infection and other immune challenges; Finnerty CM et al.; Manduca sexta larvae infected per os with a sublethal dose of Erinnyis ello granulosis virus (EeGV) contain an induced plasma protein of ca 33-36 kDa {Finnerty et al . (1994) J . Invertebr . Pathol . 63, 140-144} . This virus-induced protein shares characteristics with scolexin, a bacteria-induced plasma protein from M . sexta, so in this study we compared the two proteins . Two-dimensional gel electrophoresis reveals the induction of polypeptides corresponding to the subunits of scolexin in the plasma from EeGV-infected, as well as bacteria-injected, larvae . Immunoblots of these two-dimensional polyacrylamide gels show that antiserum against the virus-induced protein cross-reacts with the putative scolexin polypeptides induced by either EeGV infection or bacteria injection . Amino acid analysis of the virus-induced protein shows it to be very similar to scolexin, and the N-terminal sequences of the two proteins are nearly identical . From these data, we conclude that the virus-induced protein and scolexin are identical, or at least isoforms of the same protein . Using immunoblot, we also demonstrate that scolexin is induced in M . sexta plasma by injection with yeast or lipopolysaccharide from Serratia marcescens. J Bone Joint Surg Am, 1997 Jan, 79(1), 36 - 43 Infection around joint replacements in patients who have a renal or liver transplantation; Tannenbaum DA et al.; The results of thirty-five joint (hip or knee) replacements in nineteen patients who had an organ transplantation were retrospectively reviewed . The patients received a standard immunosuppressive induction regimen at the time of the transplantation and were maintained on a combination of prednisone, azathioprine, and cyclosporine A . All patients received antibiotics perioperatively, but antibiotic-impregnated bone cement was not used for any procedure . Six joint replacements, in three patients who were an average of 48.2 years old at the time of the arthroplasty, were performed before a renal transplantation . Twenty-four joint replacements, in fourteen patients who were an average of 40.9 years old at the time of the arthroplasty, were performed after an organ transplantation . Two patients, who were an average of 53.8 years old at the time of the arthroplasty, each had a joint replacement both before and after a liver transplantation (a total of five joint replacements) . The average duration of follow-up from the first joint replacement was 8.8 years (range, one to twenty-three years) . The Harris hip score or The Hospital for Special Surgery knee score was determined at the time of the latest follow-up examination . An infection developed around the implant in five patients who had had the joint replacement after a transplantation . The average interval from implantation of the prosthesis until detection of the infection was 3.4 years (range, one to six years) . One patient who had a liver transplant was infected with Pseudomonas aeruginosa and another one was infected with Escherichia coli . One patient who had a renal transplant was infected with Staphylococcus epidermidis; one, with Enterococcus; and one, with Serratia marcescens . We found that patients who had a joint replacement after an organ transplantation had a very high risk of devastating infection . The rate of such infection was 19 per cent (five of twenty-seven joint replacements in sixteen patients). J Clin Microbiol, 1997 Jan, 35(1), 59 - 63 Identification of capsular antigens in Serratia marcescens; Aucken HM et al.; Previous studies with 31 strains of Serratia marcescens, including 28 reference O-serotype strains, have indicated that 19 of them have an acidic polysaccharide which copurifies with lipopolysaccharide during phenol-water extraction . Polysaccharide in crude extracts from 18 of the 19 strains was precipitated with Cetavlon (hexadecyltrimethyl ammonium bromide), and capsules were demonstrated around these 18 strains by Indian ink exclusion zones . Capsule-antibody binding by the Quellung reaction suggested that the acidic polysaccharide formed the capsule around the bacterial cells . Anticapsular (anti-K) antibody was detected in reference O antisera which had been prepared against boiled whole cells . Cross-titration and absorption studies revealed 14 different K antigens among these strains. FEMS Immunol Med Microbiol, 1996 Dec 31, 16(3-4), 299 - 307 Culture conditions affect cytotoxin production by Serratia marcescens; Carbonell GV et al.; Cytotoxins have been implicated in the pathogenesis of bacterial infections . In this study, the influence of different culture conditions was evaluated on cytotoxin production of Serratia marcescens . Parameters such as culture media, incubation temperature, starting pH of culture medium, aeration, anaerobiosis, carbon sources, iron concentration in he culture media, and release of cell-bond toxin by polymyxin B were investigated . The data suggest that this cytotoxin is predominantly extracellular and is not induced by iron limitation . Aerobic culture with shaking resulted in higher cytotoxicity than static aerobic or anaerobic culture . Bacteria grown in glucose, sucrose or galactose were more cytotoxic than those grown in inositol or maltose . The culture conditions that were identified as optimal for cytotoxin production by Serratia marcescens were incubation temperature ranging from 30 to 37 degrees C, in medium adjusted pH 8.5, with shaking . This work will contribute to further studies on the identification of this cytotoxic activity. Microbiologia, 1996 Dec, 12(4), 607 - 12 Epidemiological markers of Serratia marcescens isolates causing nosocomial infections in Spain (1981-1991); Boquete T et al.; The distribution of epidemiological markers (serotyping and phage-typing) of Serratia marcescens isolates from nosocomial episodes (63 nosocomial cutbreaks with 475 isolates, and 1208 sporadic cases) received in our laboratory during the period 1981-1991 was studied . The records for 1683 isolates from Spanish hospitals have been analyzed . In relation with the sporadic cases, the predominant types were serotype O6 (13.4%) and serotype O14 (11.4%); polyagglutinable strains accounted for 15.6%; in outbreaks, type O14 is clearly predominant (27.4%) . Phage-typing was a good secondary marker, with a 87.9% of typability; the number of lytic patterns was very high, extended patterns (six or more phages) being the most frequent . We have studied the characteristics of S . marcescens isolates causing infections in the nosocomial environment in Spain. Eur J Clin Invest, 1996 Dec, 26(12), 1103 - 6 Helicobacter pylori and proteolytic activity; Nilius M et al.; Protease activity of 10 different H . pylori strains, purified marker proteases and protease-positive reference bacteria (Klebsiella ozaenae, Serratia marcescens) were tested against bovine haemoglobin, porcine mucin, bovine serum albumin, gelatin and casein as substrates . After incubation in development buffer and subsequent staining with Coomassie blue, protease activity bands were demonstrated as transparent spots after polyacrylamide gel electrophoresis (PAGE) on gels with incorporated substrate . Presence of protease activity was investigated in a wide pH range (pH 2.0-9.0) . Although marker proteases (0.15-0.2 microgram per slot) as well as protease-positive bacteria (2-30 micrograms per slot) clearly showed proteolytic activity in gels containing 0.1-0.2% protein mL-1, no proteolytic activity was demonstrated in any of the H . pylori strains tested . This finding indicates that H . pylori does not possess significant protease activity, as this would have been detected by this sensitive method. J Leukoc Biol, 1996 Dec, 60(6), 753 - 7 Microbial killing by human neutrophil cytokineplasts: similar suppressive effects of reversible and irreversible inhibitors of nitric oxide synthase; Malawista SE et al.; Employing anucleate, granule-poor, motile fragments from human blood neutrophils (cytokineplasts; CKP), we previously provided evidence for a new staphylococcal killing pathway for human neutrophils involving reactive nitrogen intermediates: the NO synthase inhibitor N(omega)-monomethyl-L-arginine (NMMA), an analogue of L-arginine (L-Arg), substantially decreased the killing capacity of CKP for Staphylococcus aureus (Staph), an effect reversible by excess L-Arg but not D-Arg . We have extended these findings to two irreversible NO synthase inhibitors: the first, N-iminoethyl-L-ornithine (L-NIO), is an L-Arg analogue; the other, diphenyleneiodonium (DPI), is not . After 60 min of incubation with bacteria, despite having taken up somewhat fewer staphylococci than did controls, cytoplasts treated with NO synthase inhibitors had many more live, CKP-associated bacteria: for NMMA, 6.9 times more (40.0% of the inoculum vs . 5.8%; n = 8, P = 0.003); for L-NIO, 3.6 times more (25.5 vs . 7%; n = 4, P = 0.004); for DPI, 5.8 times more (37.4 vs . 6.4%; n = 7, P = 0.002) . Results were similar after only 20 min of incubation . In two experiments in which the Gram-negative bacterium, Serratia marcescens, was employed instead of Staph, the results were again similar . In contrast, killing of either bacterium by intact neutrophils (PMN) was not inhibited by NMMA, by L-NIO, or by DPI, a failure most likely attributable to their granule content . The irreversible inhibitors of NO synthase will be especially useful in analyzing particular effects on CKP employed in multicellular systems. J Clin Microbiol, 1996 Dec, 34(12), 3138 - 41 Use of pulsed-field gel electrophoresis typing to study an outbreak of infection due to Serratia marcescens in a neonatal intensive care unit; Miranda G et al.; Serratia marcescens is a well-known cause of nosocomial infections and outbreaks, particularly in critically ill neonates and immunocompromised patients . Numerous methods have been proposed for typing . We used pulsed-field gel electrophoresis (PFGE) typing to analyze an outbreak in a neonatal intensive care unit (NICU) . We included 23 patient isolates from an outbreak (March to July 1995), and 10 patient isolates from different wards during the same time period . PFGE of whole-cell DNA digested by SpeI was used as a marker of strain identity . The most common presentation of the infection was sepsis in 18 of 23 (78%) neonates . Only four different biotypes were identified; biotype A8d accounted for 84% of the strains . PFGE typing revealed two clones responsible for two different clonal strain dissemination outbreaks from March to July, with 24 patient isolates being pattern A and 4 patient isolates being pattern E . PFGE typing suggests cross transmission between patients in the NICU and other wards . The isolates from 5 other patients showed distinct PFGE patterns . Extensive investigation and cultures failed to identify any environmental or staff reservoir of S . marcescens . This is one of the first reports applying PFGE to the study of S . marcescens, and this method was a useful marker of strain identity . PFGE typing distinguished strains which appeared to be the same by biotyping. FEBS Lett, 1996 Nov 18, 397(2-3), 343 - 6 Analysis of the reaction mechanism of the non-specific endonuclease of Serratia marcescens using an artificial minimal substrate; Kolmes B et al.; We have studied the mechanism of action of the Serratia nuclease using deoxythymidine 3',5'-bis-(p-nitrophenyl-phosphate) as a substrate . A comparison of the activity with which the wild-type enzyme and several mutant enzymes attack this artificial substrate and herring sperm DNA, respectively, supports the suggestion that His89 is the general base and a Mg2+ ion bound to Glu127 the general acid in the mechanism of phosphodiester bond hydrolysis by the Serratia nuclease, and that Asn119 directly participates in catalysis, for example by transition state stabilisation . Arg57, Arg87 and Arg131, essential for nuclease activity, are not needed for cleavage of the artificial substrate, suggesting that they are involved in binding and positioning of nucleic acid substrates. Mem Inst Oswaldo Cruz, 1996 Nov-Dec, 91(6), 755 - 60 Detection of extracellular proteases from microorganisms on agar plates; Vermelho AB et al.; We present herein an improved assay for detecting the presence of extracellular proteases from microorganisms on agar plates . Using different substrates (gelatin, BSA, hemoglobin) incorporated into the agar and varying the culture medium composition, we were able to detect proteolytic activities from Pseudomonas aeruginosa, Micrococcus luteus and Serratia marcescens as well as the influence that these components displayed in the expression of these enzymes . For all microorganisms tested we found that in agar-BHI or yeast extract medium containing gelatin the sensitivity of proteinase detection was considerably greater than in BSA-agar or hemoglobin-agar . However, when BSA or hemoglobin were added to the culture medium, there was an increase in growth along with a marked reduction in the amount of proteinase production . In the case of M . luteus the incorporation of glycerol in BHI or yeast extract gelatin-agar induced protease liberation . Our results indicate that the technique described here is of value for detecting extracellular proteases directly in the culture medium, by means of a qualitative assay, simple, inexpensive, straight forward method to assess the presence of the proteolytic activity of a given microorganism colony with great freedom in substrate selection. Microbiology, 1996 Nov, 142 ( Pt 11), 3295 - 303 Complete sequence and organization of the Serratia marcescens biotin operon; Sakurai N et al.; The nucleotide sequence of the biotin (bio) operon of wild-type Serratia marcescens Sr41 was determined . Five ORFs were identified to encode BioA (7,8-diaminopelargonic acid aminotransferase), BioB (biotin synthase), BioF (7-keto-8-aminopelargonic acid synthase), BioC (an enzyme catalysing the synthesis of pimeloyl-CoA) and BioD (dethiobiotin synthase), in this order . The operon was deduced to be transcribed divergently to the left into bioA and to the right into the bioBFCD genes . The promoters and a common predicted operator for both bioA and bioBFCD genes were located between the bioA and bioB genes . The predicted amino acid sequences of these enzymes were similar to the sequences of the corresponding enzymes of Escherichia coli . Analysis of expression of the lacZ structural gene fused with the bioA and bioB promoters revealed that the biotin operon was subject to biotin-mediated feedback repression. J Antimicrob Chemother, 1996 Nov, 38(5), 771 - 6 The synergic effects of quinolones and oral cephem antibiotics on Serratia marcescens; Otsuki M et al.; The in-vitro effects of new quinolones and oral cephem antibiotics in various combinations on 26 strains of clinically isolated Serratia marcescens were assessed . The in-vitro activities of ofloxacin and ciprofloxacin in combination with either cefpodoxime or cefcamate were evaluated by the chequerboard titration method . These combinations showed synergistic and additive effects against most of the S . marcescens tested but no antagonism was observed . Time-kill experiments performed with two representative isolates of S . marcescens showed synergic effects with respect to the kill rates, when concentrations of quinolones and beta-lactam antibiotics, exhibiting bacteriostatic effects were combined . Exposure of S . marcescens to ciprofloxacin before the addition of cefpodoxime had no influence on the combination effect . When cefpodoxime was added first, however, the bactericidal effect was reduced . The induction of beta-lactamase by cefmetazole was enhanced by the combination of ciprofloxacin and cefmetazole . These results suggest that the synergic effects observed between new quinolones and cephem antibiotics are due to the stimulation of incorporation of cephems by combination with quinolones. J Invertebr Pathol, 1996 Nov, 68(3), 275 - 7 Restricted Ingestion of Bacteria by Fire Ants Jouvenaz DP, Lord JC, Undeen AH. Fire ant queens and workers from colonies fed to repletion on Serratia marcescens, Bacillus thuringiensis, or Bacillus sphaericus were aseptically dissec