Infect Immun, 1999 Jan, 67(1), 350 - 6 Establishment of unipolar localization of IcsA in Shigella flexneri 2a is not dependent on virulence plasmid determinants; Sandlin RC et al.; Unipolar localization of IcsA on the surface of Shigella flexneri is required for efficient formation of actin tails and protrusions in infected eucaryotic cells . Lipopolysaccharide (LPS) mutations have been demonstrated to affect either the establishment or the maintenance of IcsA in a unipolar location, although the mechanism is unknown . In order to analyze the contribution of virulence plasmid determinants on the unipolar localization of IcsA, we examined the localization of IcsA expressed from a cloned plasmid copy in two different genetic backgrounds . The localization of IcsA was first examined in a virulence plasmid-cured derivative of the wild-type S . flexneri 2a isolate 2457T . This approach examined the contribution of virulence plasmid-borne factors, including the previously identified virulence plasmid-borne protease that is responsible for cleaving IcsA in the outer membrane and releasing the 95-kDa secreted form from the cell surface . IcsA localization in a related but nonpathogenic Escherichia coli strain expressing LPS of the O8 serotype was also examined . IcsA surface presentation in both of these genetic backgrounds continued to be unipolar, demonstrating that virulence plasmid-borne determinants are not responsible for unipolar localization of IcsA . The unipolar localization of IcsA in the E . coli background suggests that a common pathway that allows IcsA to be spatially restricted to one pole on the bacterial cell surface exists in Shigella and E . coli. Blood, 1999 Jan 1, 93(1), 394 - 8 Peripheral blood CD14(+) cells from healthy subjects carry a circular conformation of latent cytomegalovirus genome; Bolovan-Fritts CA et al.; The majority of the human population harbors latent cytomegalovirus . Although CD14(+) peripheral blood mononuclear cells have been implicated as sites of latency, the conformation of the latent viral genome in these cells is unknown . In this study, the conformation of viral genomic DNA was assessed in CD14(+) cells from healthy virus seropositive carriers using an electrophoretic separation on native agarose gels in combination with polymerase chain reaction detection . Here we show that the viral genome migrates as a circular plasmid with a mobility equivalent to a circular 230-kb Shigella flexneri megaplasmid marker . Neither linear nor complex or integrated forms of the viral genome were detected . This report provides further evidence that the CD14(+) cell population is an important site of viral latency in the naturally infected human host . Detection of the viral genome as a circular plasmid during latency suggests that this virus maintains its genome in a manner analogous to other herpesviruses where latent viral genome conformation has been studied. Am J Med Sci, 1998 Dec, 316(6), 379 - 84 Multiresistant Shigella species isolated from pediatric patients with acute diarrheal disease; Flores A et al.; A total of 57 strains of Shigella (36 S sonnei, 21 S flexneri), isolated from children with acute diarrheal disease who presented for treatment at the Andes University Hospital, Merida, Venezuela, from June 1993 to June 1995, were tested for their susceptibility to trimethoprim, sulfamethoxazole, ampicillin, cefamandole, ceftriaxone, streptomycin, fleroxacin, and nalidixic acid, by the agar dilution method . Twenty-seven strains (75%) of S sonnei and eight strains of S flexneri (38.1%) isolates showed high-level resistance to trimethoprim (MIC90 > 1024 microg/mL), which was also associated with other resistance patterns . The most common resistant phenotype associated with trimethoprim-resistance among S sonnei isolates was sulfamethoxazole-streptomycin (63%); among S flexneri isolates, it was sulfamethoxazole-ampicillin-streptomycin (87.5%) . Individual resistance was only observed for ampicillin, mainly in four isolates of S flexneri, and in one isolate of S sonnei . Most Shigella strains were resistant to three or more antimicrobial agents . These results confirmed that multiresistant strains of Shigella are present in Merida, and emphasize the importance to maintain these under surveillance in order to assess local susceptibility patterns and empiric therapy. Commun Dis Public Health, 1998 Dec, 1(4), 279 - 80 Shigella outbreak in a school associated with eating canteen food and person to person spread; Maguire HC et al.; In June 1993 an outbreak of Shigella sonnei infection at a primary school in south east England affected 42% of 327 pupils and staff . Attack rates of diarrhoea and fever were 33% for children aged 4 to 8 years, and 8% for those aged 8 to 12 years (p < 0.00001) . Illness was associated with eating canteen food (relative risk 5.9; 95% confidence interval 3.4, -10.3) . All strains examined were S . sonnei phage type 3, with the same antibiogram (ttSTSS), and were indistinguishable using colicin typing and biotyping (colicin type 9, E8) and pulse field gel electrophoresis . Molecular epidemiology suggested but could not confirm that the outbreak strain was introduced into the school population from the community. Ann Med Interne (Paris), 1998 Oct, 149(6), 340 - 50 {Vaccination against diarrheal diseases and typhoid fever . Current status and prospects}; Ivanoff B et al.; Diarrheal diseases and typhoid fever are still common in developing countries and there is still a search for effective control measures able to prevent the epidemics they cause from time to time . There are recommended preventive measures based on health education and improvement of sewage and water facilities; however these recommendations given for many years have not reached the expected results for different reasons . Antibiotherapy was very effective for many years; unfortunately increasing antibiotic resistance has been reported, particularly in Shigella and typhoid fever treatment . This explains the re-kindled interest currently taking place in vaccines development against infections due to V . cholerae, Shigella, E.coli ETEC, S . typhi and rotavirus . The new available vaccines are very effective and provide greater protection than that given by the old killed injectable vaccines . They paved the way for development of new candidate vaccines easier to deliver (oral vaccines or one dose parenteral vaccine), which already give promising results . Some of these candidate vaccines like those related to Shigella infections are considered as a future promising tool for controlling diarrhea due to Shigella. EMBO J, 1998 Dec 1, 17(23), 7033 - 43 Thermoregulation of Shigella and Escherichia coli EIEC pathogenicity . A temperature-dependent structural transition of DNA modulates accessibility of virF promoter to transcriptional repressor H-NS; Falconi M et al.; The expression of plasmid-borne virF of Shigella encoding a transcriptional regulator of the AraC family, is required to initiate a cascade of events resulting in activation of several operons encoding invasion functions . H-NS, one of the main nucleoid-associated proteins, controls the temperature-dependent expression of the virulence genes by repressing the in vivo transcription of virF only below a critical temperature (approximately 32 degrees C) . This temperature-dependent transcriptional regulation has been reproduced in vitro and the targets of H-NS on the virF promoter were identified as two sites centred around -250 and -1 separated by an intrinsic DNA curvature . H-NS bound cooperatively to these two sites below 32 degrees C, but not at 37 degrees C . DNA supercoiling within the virF promoter region did not influence H-NS binding but was necessary for the H-NS-mediated transcriptional repression . Electrophoretic analysis between 4 and 60 degrees C showed that the virF promoter fragment, comprising the two H-NS sites, undergoes a specific and temperature-dependent conformational transition at approximately 32 degrees C . Our results suggest that this modification of the DNA target may modulate a cooperative interaction between H-NS molecules bound at two distant sites in the virF promoter region and thus represents the physical basis for the H-NS-dependent thermoregulation of virulence gene expression. J Biol Chem, 1998 Dec 4, 273(49), 32895 - 900 Shigella-induced apoptosis is dependent on caspase-1 which binds to IpaB; Hilbi H et al.; We report here that the Shigella invasion plasmid antigen (Ipa)B, which is sufficient to induce apoptosis in macrophages, binds to caspase (Casp)-1, but not to Casp-2 or Casp-3 . Casp-1 is activated and its specific substrate interleukin-1beta is cleaved shortly after Shigella infection . Macrophages isolated from Casp-1 knock-out mice are not susceptible to Shigella-induced apoptosis, although they respond normally to other apoptotic stimuli . Shigella kills macrophages from casp-3, casp-11, and p53 knock-out mice as well as macrophages overexpressing Bcl-2 . We propose that Shigella induces apoptosis by directly activating Casp-1 through IpaB, bypassing signal transduction events and caspases upstream of Casp-1 . Taken together these data indicate that Shigella-induced apoptosis is distinct from other forms of apoptosis and seems uniquely dependent on Casp-1. Membr Cell Biol, 1998, 12(1), 1 - 8 Structural features, physiological roles, and biotechnological applications of the membrane proteases of the OmpT bacterial endopeptidase family: a micro-review; Stathopoulos C; The proteins of the OmpT family represent a new class of integral membrane peptidases showing no sequence homology with other known classes of proteases . The prototype of the family, the Escherichia coli K-12 protein OmpT (or omptin), is an outer membrane endopeptidase with unusual specificity: it cleaves the peptide bond between two basic amino acids . A second distinct characteristic of OmpT is its ability to function even under extreme denaturing conditions (e.g . high concentration of urea) . There is a growing number of reports that associate the proteases of the OmpT family with pathogenicity of certain gram-negative bacteria such as Yersinia pestis, Shigella flexneri, and pathogenic E . coli strains . This article reviews recent developments in the field of the OmpT proteases, provides a guide for the recognition of residues of the active site, and finally discusses potential uses of these proteins in biotechnology applications. Carbohydr Res, 1998 Sep, 311(3), 121 - 33 Synthesis of tri- and tetrasaccharide fragments of the Shigella dysenteriae type 1 O-antigen deoxygenated and fluorinated at position 3 of the methyl alpha-D-galactopyranoside terminus; Mulard LA et al.; The blockwise synthesis of methyl alpha tri- and tetrasaccharide analogs of the biochemical repeating unit of the Shigella dysenteriae type 1 O-polysaccharide is described . Modifications include deoxygenation and deoxyfluorination at position 3 of the galactopyranoside residue . Methyl 4,6-O-benzylidene-3-deoxy-alpha-D-xylo-hexopyranoside (8) and methyl 4,6-O-benzylidene-3-deoxy-3-fluoro-alpha-D-galactopyranoside (9) were condensed with (2,3,4-tri-O-benzoyl-alpha-L-rhamnopyranosyl)-(1-->3) -2,4-di-O-benzoyl-alpha-L-rhamnopyranosyl chloride to give, after deprotection, the target trisaccharide methyl alpha-L-rhamnopyranosyl-(1-->3)-alpha-L- rhamnopyranosyl-(1-->2)-3-deoxy-alpha-D-xylo-hexopyranoside and the corresponding fluorinated oligosaccharide . For the tetrasaccharide synthesis, the glycosyl acceptors 8 and 9 were condensed with the temporarily protected (2,4-di-O-benzoyl-3-O-chloroacetyl-alpha-L- rhamnopyranosyl)-(1-->3)-2,4-di-O-benzoyl-alpha-L-rhamnopyranosyl chloride . Removal of the chloroacetyl group was followed by condensation of the resulting selectively deblocked trisaccharides with 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-glucopyranosyl chloride . Reduction and deprotection then gave the free methyl 2-acetamido-2-deoxy- alpha-D-glucopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl- (1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-3-deoxy-alpha-D-xylo-hexopyra noside and the fluorinated analog. Tidsskr Nor Laegeforen, 1998 Sep 30, 118(23), 3649 - 53 {Communicable disease control in connection with international air traffic to Norway}; Aavitsland P et al.; International air traffic has increased the risk of importation of infectious diseases to Norway . We have used notification data and a theoretical framework to assess the risk of importation and subsequent disemination of serious infectious diseases in Norway . Every year, a few cases of these diseases are imported to Norway, especially malaria, shigellosis and typhoid fever . A few secondary cases of enteric diseases may occur, but epidemics are unlikely . Counselling and immunisation of Norwegians going abroad is the first step in prevention . Secondly, health services all over the country should be able to diagnose imported diseases early and institute infection control measures . However, there is no need for concentrating resources for disease control at international airports in Norway. J Cell Biol, 1998 Nov 16, 143(4), 1003 - 12 Interferon alpha inhibits a Src-mediated pathway necessary for Shigella-induced cytoskeletal rearrangements in epithelial cells; Dumenil G et al.; Shigella flexneri, the causative agent of bacillary dysentery, has the ability to enter nonphagocytic cells . The interferon (IFN) family of cytokines was found to inhibit Shigella invasion of cultured epithelial cells . We show here that IFN-alpha inhibits a Src-dependent signaling cascade triggered by Shigella that leads to the reorganization of the host cell cytoskeleton . Immunofluorescence studies showed that IFN-alpha inhibits Shigella-induced actin polymerization required for bacterial entry into cells . Phosphorylation of cortactin, a Src-substrate specifically tyrosyl-phosphorylated during Shigella entry, was inhibited by IFN-alpha . Overexpression of a dominant interfering form of pp60c-src led to inhibition of Shigella-induced cytoskeletal rearrangements and decreased cortactin phosphorylation indicating a role for Src in Shigella entry . Also, Shigella uptake in cells that expressed constitutively active Src was unaffected by IFN-alpha treatment . We conclude that Src kinase activity is necessary for Shigella invasion of epithelial cells and that IFN-alpha inhibits this Src-dependent signaling pathway. Scand J Infect Dis, 1998, 30(4), 351 - 3 Drug resistance of Shigella strains isolated in Ankara, Turkey, 1993-1996; Aysev AD et al.; 289 Shigella strains were isolated from children at the paediatrics department of Ankara University . 75% of the isolates were S . sonnei and 24.8% were S . flexneri . Each strain was tested for resistance to 9 antimicrobial agents . 79% of the isolates were resistant to streptomycin (S), 56% to tetracycline (T), 55.7% to trimethoprim-sulfamethoxazole (SXT), 27.7% to ampicillin (Am) and 19.7% to chloramphenicol (C) . None of the isolates was resistant to ciprofloxacin, nalidixic acid, cephalothin, ampicillin-sulbactam and ceftriaxone . 56% of the isolates were resistant to 3 or more antimicrobial agents . The most frequent pattern of resistance of S . sonnei and S . flexneri strains was SXT, T, S (39.6%) and Am, SXT, T, S, C (48.6%), respectively (p < 0.0001) . These results demonstrate that trimethoprim-sulfamethoxazole should not be used in the treatment of shigellosis. J Travel Med, 1995 Jun 1, 2(2), 70 - 76 Illness in Journalists and Relief Workers Involved in International Humanitarian Assistance Efforts in Somalia, 1992-93; Sharp TW et al.; Background: Journalists and relief workers participating in international relief efforts in Somalia following the intervention of outside armed forces in late 1992, were faced with a number of threats to their health . Principally these threats were from endemic infectious diseases and trauma . Methods: In-patient, emergency clinic, and laboratory records of U.S . military field hospitals, which provided the only available sophisticated medical care in Somalia during most of the study period (December 15, 1992, to February 15, 1993), were reviewed to determine the number of workers evaluated and the causes of their illnesses . In addition, two questionnaire surveys were conducted to elucidate risk factors for illness in these groups . Results: One hundred and thirty-eight journalists and relief workers, primarily from Europe and North America, were evaluated at a hospital for a variety of common travel-associated health problems, including diarrhea (33%), acute respiratory infection (21%), other febrile illnesses (11%), hepatitis (2%), major trauma (6%), and minor trauma (13%) . Documented infectious disease pathogens included Plasmodium falciparum (7 cases), Shigella sp (3 cases), enterotoxigenic Escherichia coli (ETEC) (3 cases), dengue virus-2 (2 cases), and hepatitis E virus (3 cases) . Two relief workers were killed by gunshot wounds . In the questionnaire surveys of 104 journalists and 98 relief workers, 84% of respondents reported that they had received some pretravel medical advice, but only 70% sought a medical consultation in person . Thirty-four percent were not receiving a recommended antimalarial chemoprophylaxis regimen, and only 10% obtained a fluoroquinolone antimicrobial drug for self treatment of diarrhea . Sixty-four percent of both groups combined, reported having had diarrhea, and 26% experienced a nondiarrheal febrile illness . Sixty-eight percent reported that their work performance was adversely affected by illness . In multivariate logistic regression analyses, factors associated with an increased risk of diarrhea were age < 35 years (OR 1.5, 95% CI 1.1-1.9); residence in Somalia for more than 21 days (OR 1.7, 95% CI 1.3-2.1); and regular consumption of local food and water (OR 3.8, 95% CI 3.4-4.2) . Factors associated with nondiarrheal febrile illness were age < 35 years (OR 1.4, 95% CI 1.1-1.8); residence in Somalia for more than 21 days (OR 1.8, 95% CI 1.4-2.2); and not having had an in-person pretravel medical consultation (OR 2.0, 95% CI 1.5-3.0) . Conclusions: These data indicate that journalists and relief workers who traveled to Somalia in response to the massive humanitarian crisis themselves experienced substantial health problems . Improved pretravel medical preparation might prevent or limit illness in these unique groups and improve the efficiency of future disaster response efforts . (J Travel Med 2:70-76, 1995) Proc Natl Acad Sci U S A, 1998 Nov 10, 95(23), 13917 - 22 Vaccinia locomotion in host cells: evidence for the universal involvement of actin-based motility sequences ABM-1 and ABM-2; Zeile WL et al.; Vaccinia uses actin-based motility for virion movement in host cells, but the specific protein components have yet to be defined . A cardinal feature of Listeria and Shigella actin-based motility is the involvement of vasodilator-stimulated phosphoprotein (VASP) . This essential adapter recognizes and binds to actin-based motility 1 (ABM-1) consensus sequences {(D/E)FPPPPX(D/E), X = P or T} contained in Listeria ActA and in the p90 host-cell vinculin fragment generated by Shigella infection . VASP, in turn, provides the ABM-2 sequences {XPPPPP, X = G, P, L, S, A} for binding profilin, an actin-regulatory protein that stimulates actin filament assembly . Immunolocalization using rabbit anti-VASP antibody revealed that VASP concentrates behind motile virions in HeLa cells . Profilin was also present in these actin-rich rocket tails, and microinjection of 10 microM (intracellular) ABM-2 peptide (GPPPPP)3 blocked vaccinia actin-based motility . Vinculin did not colocalize with VASP on motile virions and remained in focal adhesion contacts; however, another ABM-1-containing host protein, zyxin, was concentrated at the rear of motile virions . We also examined time-dependent changes in the location of these cytoskeletal proteins during vaccinia infection . VASP and zyxin were redistributed dramatically several hours before the formation of actin rocket tails, concentrating in the viral factories of the perinuclear cytoplasm . Our findings underscore the universal involvement of ABM-1 and ABM-2 docking sites in actin-based motility of Listeria, Shigella, and now vaccinia. J Zoo Wildl Med, 1998 Sep, 29(3), 261 - 8 Protein deficiency in a colony of western lowland gorillas (Gorilla g . gorilla) Mundy NI, Ancrenaz M, Wickings EJ, Lunn PG. A syndrome of alopecia and weight loss in a colony of 10 western lowland gorillas (Gorilla gorilla gorilla) in Gabon during a 3-yr period was apparently due to a dietary protein deficiency, with nine individuals affected to some extent . The most severely afflicted was a 4-yr-old female who eventually died as a result of acute gastroenteritis caused by Shigella flexneri . Clinical signs included chronic alopecia, hair discoloration, failure to thrive, and weight loss, and their severity was directly correlated with the degree of hypoalbuminemia (12 g/L in the most extreme case) and normocytic normochromic anemia . Preliminary clinical tests and autopsy results suggested a dietary protein or amino acid deficiency as the cause of the hypoalbuminemia, and further analyses of serum amino acid and protein levels were consistent with a diagnosis of dietary protein deficiency . Supplementation of the colony diet with a protein preparation for humans produced a rapid amelioration of signs and improvement in body and coat condition, a normalization of serum albumin and total protein levels, and disappearance of the anemia in all affected animals except a 12-yr-old male, who responded well to treatment with anabolic steroids . The natural diet of western lowland gorillas is surprisingly high in protein, and the dietary protein requirement of captive gorillas may be increased as a result of the absence of commensal gastrointestinal ciliates. APMIS, 1998 Sep, 106(9), 879 - 83 Antimicrobial susceptibilities and beta-lactamase production of Shigella isolates in Crete, Greece, during the period 1991-1995; Maraki S et al.; The susceptibility to 11 antibiotics was determined for 52 strains of Shigella isolated from patients with diarrheal disease in Crete, Greece, during the period 1991-1995 . Forty-six percent of the isolates were resistant to ampicillin, 48% to tetracycline, 44.2% to chloramphenicol, and 28.8% to cotrimoxazole . Shigella flexneri was more resistant than S . sonnei to ampicillin (82 vs 4.3%), to tetracycline (82 vs 8.7%) and to cotrimoxazole (42.8 vs 13%) . Overall, 82% of all S . flexneri isolates were resistant to the three or four antimicrobial agents tested . The beta-lactamases produced by shigellae were identified by isoelectric focusing and were found to be OXA-1, TEM-1, and a low-level beta-lactamase with a pI>8 . The results from the present study, which is the first carried out in Crete, emphasize the need for continuous surveillance of resistance and control of antibiotic usage. Rev Cubana Med Trop, 1995, 47(2), 131 - 4 {Septicemia due to Shigella . A case report and review of the literature}; Ben Salas C et al.; Knowing that the isolation of Shigella in blood is considered as an unusual medical event, a case of an infant deceased from septicemia by Shigella sonnei is presented here . This is the first case of the kind reported in Pinar del Rio province . A review of the literature is included. Kansenshogaku Zasshi, 1998 Sep, 72(9), 935 - 8 {A case of bacillary dysentery caused by new quinolone-resistant Shigella flexneri 2a}; Yoshimura K et al.; A 73-year-old male was admitted to our hospital because of detection of Shigella flexneri 2a from his stool . Antimicrobial treatment with levofloxacin (LVFX) was started, but could not eliminate the organism in the stool . In the examination of drug susceptibility, this strain was highly resistant to all new quinolones . The minimal inhibitory concentration of norfloxacin, ofloxacin and ciprofloxacin to this strain was 12.5 micrograms/ml, 6.25 micrograms/ml and 6.25 micrograms/ml, respectively . The dual mutations were detected in the codon 83 and 87 of the gyrA gene by sequencing the quinolone-resistance determining region (QRDR) . There was, however, no significant difference between the intracellular uptake of ciprofloxacin in this strain and in the ciprofloxacin-sensitive strain . The amount of ciprofloxacin in this strain unchanged when carbonyl cyanide m-chlorophenyl hydrazone (CCCP) was added . These results suggest that the advanced resistance in Shigella flexneri against new quinolones could be acquired by only this dual mutations without the change of the active efflux mechanism. Sante, 1998 Jul-Aug, 8(4), 303 - 5 {Ciprofloxacin in the treatment of dysentery caused by type 1 Shigella dysenteriae during an epidemic in Rwandan refugees in Goma in 1994}; Laureillard D et al.; There was an outbreak of dysentery caused by type I Shigella dysenteriae among Rwandan refugees at Goma, in what was then Zaire, in 1994 . The causal organism was resistant to all antibiotics available from the public health authorities . The only effective antimicrobial agent available was ciprofloxacin . It was given to 326 inpatients at the Medecins Sans Frontieres (MSF) Center, mostly children under the age of 5, pregnant women and immunocompromised patients . A standard dose schedule was used: 1 g ciprofloxacin per day in two doses for 5 days for adults, 250 mg for children weighing less than 20 kg and 500 mg for children weighing less than 50 kg . The treatment was effective in 285 patients (85.6%) according to clinical criteria . Treatment was unsuccessful in 6 patients and 14 decided to stop taking the medication although it was having a positive effect . No side effects clearly caused by the treatment have been reported . This is consistent with previous reports showing that ciprofloxacin is clinically effective against epidemic dysentery caused by multi-drug resistant Shigella dysenteriae type I . However, fluoroquinolones are expensive and difficult to obtain and their use would require improvements in logistics and compliance. Mikrobiol Z, 1998 May-Jun, 60(3), 63 - 9 {The inductive immunosuppressive activity of the lipopolysaccharide from Shigella sonnei R forms}; Borisova EV; Investigations have been carried out to find the position of lypopolysaccharide (LPS) structural part which can be activated by the redox system and to study peculiarities of its activation . Cell-free culture filtrate (CF) of Shigella sonnei strain R colonies on the nutrient agar medium was used . It was shown that CF contained three active fractions possessing inductive immunosuppressive properties . From all the phenol-water LPS fractions only lipid A possessed activity after redox treatment . O-chain and our fractions did not express such activity . The results of our investigations have shown that inductive immunosuppressive activity of the Shigella sonnei LPS was determined by lipid A. Nutrition, 1998 Oct, 14(10), 780 - 3 Local and systemic effects of macrophage cytokines in intestinal inflammation; Murch SH; The activation of macrophages and newly recruited monocytes appears to be common to both Crohn's disease and ulcerative colitis, despite different inductive stimuli . Similar activation occurs acutely during the course of invasive intestinal infections such as shigellosis, but is then usually downregulated . The macrophage cytokines tumor necrosis factor-alpha and interleukin-1 (IL-1) are centrally involved in the local inflammatory response, and blockade of either cytokine greatly attenuates the inflammatory lesion . Induction of focal vascular thrombosis and matrix degradation are thought to be an important component of this focal damage . Both cytokines and IL-6 are now recognized to contribute to the systemic effects of intestinal disease, including growth suppression, anorexia, and chronic anemia . Disturbance of sleep patterns, mood, and affect may also occur, and recent evidence points towards bidirectional interplay between macrophage cytokines and central nervous system function. Microbiology, 1998 Sep, 144 ( Pt 9), 2667 - 72 Shigella and enteroinvasive Escherichia coli strains are derived from distinct ancestral strains of E . coli; Rolland K et al.; The differentiation between Shigella subspecies, and the phylogenetic position of Shigella clones within Escherichia coli clones was determined by analysis of restriction fragment length polymorphisms of rDNA (ribotyping) . Seventy-five Shigella strains belonging to the four subspecies and 13 enteroinvasive E . coli (EIEC) strains were compared with the 72 E . coli strains of the ECOR collection, which have been classified into four phylogenetic groups (A, B1, B2 and D) . Seventeen Shigella dysenteriae ribotypes, 12 Shigella flexneri ribotypes, 23 Shiegella boydii ribotypes, 12 Shigella sonnei ribotypes and 13 EIEC ribotypes were identified following digestion with HindIII and EcoRI . Correspondence analysis of the data showed that S . boydii serotype 13 strains were distantly related to the other Shigella strains, and that S . sonnei and S . flexneri were distinct from S . boydii and S . dysenteriae . The ribotypes of Shigella and ECOR strains were indistinguishable, and S . sonnei, S . flexneri and most S . dysenteriae strains were closely related to phylogenetic group D, whereas S . dysenteriae serotype 1 strains belonged to phylogenetic group B1, and S . boydii strains were evenly distributed between the two groups . The Shigella strains were distantly related to group B2, which contains E . coli strains frequently implicated in extra-intestinal infections in humans . In contrast, the 13 EIEC strains were more widely distributed between phylogenetic groups B1, A and B2 . Thus, there was no primordial Shigella species and Shigella and EIEC strains are derived from different ancestral strains. Tsitologiia, 1998, 40(6), 524 - 8 {Invasion of Escherichia coli A2 induces reorganization of actin microfilaments in Hep-2 cells}; Efremova TN et al.; Bacteria of spontaneously isolated non-pathogenic strain E . coli A2 have been previously shown to produce a new proteinase, referred to as protease ECP 32, which specifically cleaves actin (Khaitlina et al., 1988; Matveyev et al., 1996) . Similar proteinase activity was found in revertants of Shigella flexneri L-forms . In this work immunofluorescence and electron microscopy were used to address a question of whether E . coli A2 can invade epithelial cells similarly as it has been demonstrated for Sh . flexneri . Infection of Hep-2 cells with E . coli A2 resulted in bacterial invasion of the cells followed by cytoskeleton reorganization . On one end of intracellular bacteria bundles of actin filaments resembling a comet-like tail were observed . Bacteria of referent strain CCM 5172, not producing protease ECP 32, were not taken up by the cells . These data suggest that protease ECP 32 may be involved in the process of bacterial invasion and cytoskeleton reorganization. J Nutr, 1998 Oct, 128(10), 1688 - 91 Increased height gain of children fed a high-protein diet during convalescence from shigellosis: a six-month follow-Up study; Kabir I et al.; The impact of dietary supplementation on catch-up growth was evaluated in 69 malnourished children ages 24-60 mo after recovery from shigellosis . They were fed either a high-protein (HP) diet with 15% of energy as protein, or a standard-protein (SP) diet with 7.5% energy as protein, for 3 wk in a metabolic study ward . Children were followed up bi-weekly for 6 mo by trained health assistants when anthropometric measurements and information of any illness were collected . Thirty-one children in the HP group and 28 children in the SP group completed 6-mo follow-up . The increase in height (mean +/- SD) was 5.3 +/- 1.0 cm vs . 4.1 +/- 1.1 cm for HP and SP groups, respectively (P < 0.001), whereas increase in body weight was 1.39 +/- 0.58 and 1.29 +/- 0.72 kg for children fed HP and SP, respectively (P = 0.59) . The proportion of children who were severely stunted (< -2 SD height-for-age) decreased from 45 to 29% in the HP group compared to 50 to 46% in the SP group (P < 0.05) at 6-mo follow-up . The number of diarrheal episodes per child tended to be lower in the HP vs . SP than in the SP group (1.9 vs . 2.3, P = 0.41) . These results demonstrate that feeding an HP diet to the malnourished children during recovery from shigellosis enhanced linear growth with a modest reduction in diarrheal morbidity during the 6-mo follow-up period. Med Pregl, 1998 Jul-Aug, 51(7-8), 305 - 9 {Shigellae isolated in 1997--plasmid profiles and antibiotic resistance}; Jelesic Z et al.; INTRODUCTION: Shigella spp is one of the most frequently isolated bacteria causing acute diarrhea with us . Genetics of pathogenicity of Shigella spp . includes chromosomal and plasmid genes . Most virulence factors are coded by invasion plasmid antigen genes residing on a 180-230 MDa plasmid . There is a big problem with multiple resistance of Shigella spp . strains, which is mostly plasmid-borne . Genetic analysis of bacterial cells, that is plasmid profile analysis, is important for investigation of sources and ways of spreading of the infection . All isolates originating from the same clone have identical plasmid profiles, i.e . number and size of plasmids . The aim of the investigation was: comparing the type of resistance to antimicrobical agents found in epidemic and nonepidemic . Shigella strains isolated in 1997, analyzing plasmid profiles of these isolates and confirming their epidemic connection . MATERIAL AND METHODS: Susceptibility to antibiotics was examined by a standard disc-diffusion method . Plasmid profiles of 40 strains (20 from the outbreak and 20 from sporadic cases) were tested using a method of alkaline lysis by Birnboim and Doly followed by electrophoresis in agarose gel . RESULTS: Shigella strains were resistant to antimicrobial agents which are most commonly used . Epidemic isolates shared the same resistance type, they were resistant to cephalexin, streptomycin and co-trimoxazole . The dominant type of resistance of nonepidemic strains was to ampicillin, streptomycin and co-trimoxazole . Strains isolated during the outbreak had identical plasmid profiles (2 plasmid bands of 55 and 1.5 MDa) . Non-epidemic isolates had different plasmid profiles as well as type of resistance . CONCLUSION: Strains of Shigella spp . isolated during an outbreak had the same type of resistance and the same plasmid profiles, which indicated their origin from the same clone . The plasmid profile analysis is a reliable and precise method for determination of epidemic connection of Shigella isolates. Rev Cubana Med Trop, 1994, 46(3), 148 - 51 {Ampicillin resistance mediated by the R plasmid in strains of Shigella flexneri}; Ramirez MM et al.; Forty Shigella flexneri strains isolated from children attended to at the Children's Hospital of Camaguey during an outbreak of acute diarrheal disease were studied; the minimal inhibitory concentration of ampicillin was determined . 33 strains (82.5%) were resistant to higher concentrations: 8 to 16 micrograms/mL, and 7 were susceptible to 4 micrograms/mL concentrations . Resistance plasmid (R) extraction was carried out in all the isolated strains and a common plasmid was found this plasmid was purified and transferred to Escherichia coli HE 101 . Resistance transmission was tested. Res Microbiol, 1998 Jan, 149(1), 15 - 25 A role for H-NS in the regulation of the virF gene of Shigella and enteroinvasive Escherichia coli; Prosseda G et al.; We have investigated the role of H-NS, one of the major components of the bacterial nucleoid, in the expression of the virF gene present on the large virulence plasmid of Shigella and enteroinvasive Escherichia coli in response to different environmental conditions . VirF is an AraC-like protein which activates at least two promoters, virB and virG, both repressed by H-NS . Band shift experiments reveal that the affinity of H-NS for the virF and virB promoters is comparable, while the affinity for the virG promoter is higher . Polyacrylamide gel electrophoresis of three DNA fragments containing the virF, the virB and the VirG promoters demonstrates, in agreement with computer predictions, that they have an intrinsically curved structure, confirming the preference of H-NS for bent DNA . In vivo transcriptional analysis of virF mRNA shows that H-NS negatively controls the expression of virF at 30 degrees C . The expression of a virF-lacZ translational fusion in E.coli wild type and in an hns-defective derivative grown at 30 degrees or 37 degrees C and at pH 6.0 or 7.0 indicates that, in the absence of H-NS, virF expression becomes insensitive to temperature and to limited pH changes . Our results strongly suggest that H-NS controls virF expression by binding to the virF promoter and by repressing its expression at low temperature and at low pH. Eur J Immunol, 1998 Sep, 28(9), 2726 - 37 Major histocompatibility complex class I presentation of exogenous soluble tumor antigen fused to the B-fragment of Shiga toxin; Lee RS et al.; Targeting exogenous antigen into the MHC class I-restricted presentation pathway is a prerequisite for the induction of cytotoxic T lymphocytes (CTL) which have been shown to represent an important component of the protective and therapeutic immune response to viral infections and tumors . In this study, we produced recombinant proteins composed of the receptor-binding non-toxic B-fragment of bacterial Shiga toxin derived from Shigella dysenteriae associated with an epitope from a model tumor antigen, Mage 1 . We show that Shiga B-Mage 1 fusion proteins carrying an active or inactive endoplasmic reticulum retrieval signal (the C-terminal peptides KDEL or KDELGL, respectively) could be presented by peripheral blood mononuclear cells in an MHC class I-restricted manner to Mage 1-specific CTL . After pulsing B lymphoblastoid cells or dendritic cells with Shiga B-Mage 1 fusion protein, activation of the MHC class I-restricted Mage 1-specific CTL was also demonstrated . In further analysis, we showed that treatment with brefeldin A or paraformaldehyde fixation of Epstein-Barr virus-transformed B cells prevented the presentation of the Mage 1 T cell epitope, which excluded extracellular processing of the antigen . Immunofluorescence analysis also revealed that the Shiga B-Mage 1 fusion protein was largely excluded from Lamp-2-positive lysosomal structures . Therefore, the ability of Shiga toxin B-fragment to target dendritic cells and B cells and to direct antigen into the exogenous class I-restricted pathway makes it an attractive non-living and non-toxic vaccine vector. Dig Dis Sci, 1998 Sep, 43(9), 2111 - 6 Quantitative and ultrastructural analysis of rectal mucosal mast cells in acute infectious diarrhea; Pulimood AB et al.; The role of mast cells, potential mediators of mucosal immunity and inflammation, was studied morphologically in the rectal mucosa in two acute diarrheal diseases, cholera and shigellosis . Quantitation of mucosal mast cells showed that they were significantly higher in the deeper lamina propria where blood vessels and nerves were more abundant . There was no difference in mast cell counts or degranulation in the mucosa in both groups of patients and controls . Intraepithelial mast cells were decreased in the patients . The prevalence of lipid bodies was significantly higher in mast cells from patients with cholera and shigellosis (P < 0.01) . These findings suggest that mast cell populations are more dense around blood vessels and nerves and that inflammatory mediators derived from arachidonic acid metabolites, as indicated by the lipid bodies, are the response of mast cells to the alterations in diarrhea, despite differences in the etiology of diarrhea. J Bacteriol, 1998 Oct, 180(19), 5260 - 2 H-NS regulates DNA repair in Shigella; Palchaudhuri S et al.; We report a new role for H-NS in Shigella spp.: suppression of repair of DNA damage after UV irradiation . H-NS-mediated suppression of virulence gene expression is thermoregulated in Shigella, being functional at 30 degrees C and nonfunctional at 37 to 40 degrees C . We find that H-NS-mediated suppression of DNA repair after UV irradiation is also thermoregulated . Thus, Shigella flexneri M90T, incubated at 37 or 40 degrees C postirradiation, shows up to 30-fold higher survival than when incubated at 30 degrees C postirradiation . The hns mutants BS189 and BS208, both of which lack functional H-NS, show a high rate of survival (no repression) whether incubated at 30 or 40 degrees C postirradiation . Suppression of DNA repair by H-NS is not mediated through genes on the invasion plasmid of S . flexneri M90T, since BS176, cured of plasmid, behaves identically to the parental M90T . Thus, in Shigella the nonfunctionality of H-NS permits enhanced DNA repair at temperatures encountered in the human host . However, pathogenic Escherichia coli strains (enteroinvasive and enterohemorrhagic E . coli) show low survival whether incubated at 30 or 40 degrees C postirradiation . E . coli K-12 shows markedly different behavior; high survival postirradiation at both 30 and 40 degrees C . These K-12 strains were originally selected from E . coli organisms subjected to both UV and X irradiation . Therefore, our data suggest that repair processes, extensively described for laboratory strains of E . coli, require experimental verification in pathogenic strains which were not adapted to irradiation. Epidemiol Infect, 1998 Aug, 121(1), 43 - 8 Shigella infections among children in Andaman--an archipelago of tropical islands in Bay of Bengal; Ghosh AR et al.; Shigellosis is common among children in the Andaman and Nicobar islands . Our experience showed two distinct features of shigellosis within a span of 3 years in 1994-6: (i) changing patterns of serotype or subtype specific shigellosis and (ii) emergence of multidrug resistant isolates with changing R-patterns . The rate of isolation was 10.4-27.9% with the rate of isolation of Shigella flexneri interchanging with S . dysenteriae alternately . In 1994, S . flexneri superseded S . dysenteriae (48.6% vs . 33.3%; P < 0.05) while S . dysenteriae dominated over S . flexneri in 1995 (54.7% vs . 34.0%; P < 0.05) . The picture reversed again in 1996 (63.0% vs . 22.2%; P < 0.05) . Among shigellae isolates, the commonest serotypes were S . dysenteriae type 1 and S . flexneri type 2a . Isolated shigellae were of multidrug resistant type . Seven R-patterns were observed in 1994, while 8R-patterns were observed during the next year with the emergence of nalidixic acid resistance . In 1996, emergence of gentamicin resistance was also observed . All isolates were resistant to ampicillin and sensitive to quinolones . The MIC of nalidixic acid and gentamicin are > or = 128 microg/ml and > or = 64 microg/ml respectively . These changing trends in shigellosis has important public health significance. Infect Immun, 1998 Oct, 66(10), 4957 - 64 Expression of the virulence plasmid-carried apyrase gene (apy) of enteroinvasive Escherichia coli and Shigella flexneri is under the control of H-NS and the VirF and VirB regulatory cascade; Berlutti F et al.; The transcription of the virulence plasmid (pINV)-carried invasion genes of Shigella flexneri and enteroinvasive Escherichia coli (EIEC) is induced at 37 degreesC and repressed at 30 degreesC . In this work, we report that the O135: K-:H- EIEC strain HN280 and S . flexneri SFZM53, M90T, and 454, of serotypes 4, 5, and 2a, respectively, produce apyrase (ATP-diphosphohydrolase), the product of the apy gene . In addition, the S . flexneri strains, but not the EIEC strain, produce a nonspecific phosphatase encoded by the phoN-Sf gene . Both apy and phoN-Sf are pINV-carried loci whose contribution to the pathogenicity of enteroinvasive microorganisms has been hypothesized but not yet established . We found that, like that of virulence genes, the expression of both the apy and the phoN-Sf genes was temperature regulated . Strain HN280/32 (a pINV-integrated avirulent derivative of HN280 which has a severe reduction of virB transcription) expressed the apy gene in a temperature-regulated fashion but to a much lower extent than wild-type HN280, while the introduction of the Deltahns deletion in HN280 and in HN280/32 induced the wild-type temperature-independent expression of apyrase . These results indicated that a reduction of virB transcription, which is known to occur in the pINV-integrated strain HN280/32, accounts for reduced apyrase expression and that the histone-like protein H-NS is involved in this regulatory network . Independent spontaneously generated mutants of HN280 and of SFZM53 which had lost the capacity to bind Congo red dye (Crb-) were isolated, and the molecular alterations of pINV were evaluated by PCR analysis . Alterations of pINV characterized by the absence of virF or virB and by the presence of the intact apy locus or intact apy and phoN-Sf loci were detected among Crb- mutants of HN280 and SFZM53, respectively . While all Crb- apy+ mutants of HN280 failed to produce apyrase, Crb- apy+ phoN-Sf+ mutants of SFZM53 lacked apyrase activity but produced a nonspecific phosphatase, like parental SFZM53 . Moreover, the introduction of recombinant plasmids carrying cloned virF (pMYSH6504) or virB (pBN1) into Crb- mutants of HN280 and SFZM53 lacking virF or virB, respectively, fully restored temperature-dependent apyrase expression to levels resembling those of the parental strains . Taken together, our results demonstrate that, as has already been shown for invasion genes, apy is another locus whose expression is controlled by temperature, H-NS, and the VirF and VirB regulatory cascade . In contrast, the temperature-regulated expression of the nonspecific phosphatase does not appear to be under the control of the same regulatory network . These findings led us to speculate that apyrase may play a role in the pathogenicity of enteroinvasive bacteria. Infect Immun, 1998 Oct, 66(10), 4700 - 10 Identification of two Shigella flexneri chromosomal loci involved in intercellular spreading; Hong M et al.; The ability of Shigella flexneri to multiply within colonic epithelial cells and spread to adjacent cells is essential for production of dysentery . Two S . flexneri chromosomal loci that are required for these processes were identified by screening a pool of TnphoA insertion mutants . These mutants were able to invade cultured epithelial cells but could not form wild-type plaques . Analysis of the nucleotide sequence indicated that the sites of TnphoA insertion were within two different regions that are almost identical to Escherichia coli K-12 chromosomal sequences of unknown functions . One region is located at 70 min on the E . coli chromosome, upstream of murZ, while the other is at 28 min, downstream of tonB . The mutant with the insertion at 70 min was named vpsC because it showed an altered pattern of virulence protein secretion . The vpsC mutant formed pinpoint-sized plaques, was defective in recovery from infected tissue culture cells, and was sensitive to lysis by the detergent sodium dodecyl sulfate . Recombinant plasmids carrying the S . flexneri vpsA, -B, and -C genes complemented all of the phenotypes of the vpsC mutant . A mutation in vpsA resulted in the same phenotype as the vpsC mutation, suggesting that these two genes are part of a virulence operon in S . flexneri . The mutant with the insertion at 28 min was interrupted in the same open reading frame as S . flexneri ispA . This ispA mutant could not form plaques and was defective in bacterial septation inside tissue culture cells. Indian J Med Res, 1998 Jul, 108, 3 - 7 Oxidative stress response in Shigella & nonpathogenic gut bacteria; Khanduja V et al.; The effect of oxidative stress in the form of exogenous H2O2 on the survival of four species of Shigella and two nonpathogenic Gram negative gut bacteria and the role of catalase as an antioxidant enzyme, neutralizing the effect of H2O2 were examined . A significant decrease in the number of colony forming units (CFUs) after exposure to exogenous H2O2 (122 +/- 37), compared to control bacteria (218 +/- 63, P < 0.001) was observed . There was an induction of catalase activity after exposure to exogenous H2O2 and the specific activity of catalase in H2O2 exposed bacteria was significantly increased (2.88 +/- 1.25), compared to control bacteria (1.5 +/- 0.44; P < 0.05) . A direct correlation was observed between the decrease in bacterial counts and increase in catalase activity after exposure of H2O2 (regression coefficient (0.56) . Gut bacteria appear to be susceptible to oxidative stress and inducible catalase activity may form an important part of the antioxidant defence mechanism against oxidative stress. Carbohydr Res, 1998 Jul, 309(3), 219 - 26 Binding of modified fragments of the Shigella dysenteriae type 1 O-specific polysaccharide to monoclonal IgM 3707 E9 and docking of the immunodeterminant to its modeled Fv; Miller CE et al.; The O-specific polysaccharide (O-SP) of Shigella dysenteriae type 1 has been shown by others to have the structure-->3)-alpha-L-Rhap-(1-->3)-alpha-L-Rhap-(1-->2)-alp ha-D- Galp-(1-->3)-alpha-D-GlcpNAc-(1--> . We have shown in the past that IgM 3707 E9, an anti S . dysenteriae type 1 O-SP monoclonal antibody, binds specifically to the -alpha-L-Rhap-(1-->2)-alpha-D-Galp-determinant of the polysaccharide . In this report we show that determinant to have hydrogen bonds, necessary for binding to the antibody, involving positions 3, 4 and 6 of the galactopyranosyl residue . The hydroxyl groups of the rhamnopyranosyl moiety of the immunodeterminant appear not to partake in hydrogen-bond interactions with the antibody . A model is presented of the Fv of IgM 3707 E9 based on our previously established cDNA-sequence and two known, highly homologous immunoglobulin crystal structures . The methyl glycoside of the immunodeterminant alpha-L-rhamnopyranosyl-(1-->2)-alpha-D-galactopyranose is docked to the combining area of the Fv. FEMS Microbiol Lett, 1998 Sep 1, 166(1), 79 - 87 Serotype conversion of a Shigella flexneri candidate vaccine strain via a novel site-specific chromosome-integration system; Guan S et al.; Shigella flexneri SFL124 (serotype Y) is a promising live oral vaccine candidate, which has been shown to be safe and immunogenic in human volunteers . To change the serotype of this vaccine strain, we inserted a serotype conversion gene cluster into the chromosome of SFL124 by using a bacteriophage-based site-specific integration system . By cloning an integrase gene (int), an attachment site (attP) and a glucosyl transfer gene cluster from bacteriophage SfX into a suicide vector, and subsequently introducing this construct into S . flexneri SFL124, we obtained a S . flexneri strain (designated SFL1213) expressing the serotype X somatic antigen specificity . The strain retained other characteristics of the parent strain, such as colony shape, growth rate, and Congo red binding property . Stability test showed that the serotype X O-antigen specificity in SFL1213 was 100% stable after being cultured approximately 72 successive hours under non-selective condition . In a mouse pulmonary model, the recombinant strain elicited a significant level of humoral antibodies which recognized the lipopolysaccharide (LPS) of a wild-type S . flexneri serotype X strain . The site-specific insertion system will be useful when stable expression of a cloned single copy gene is desired in the chromosome of S . flexneri vaccine candidate, SFL124. Mol Microbiol, 1998 Aug, 29(3), 677 - 84 The Shigella virulence gene regulatory cascade: a paradigm of bacterial gene control mechanisms; Dorman CJ et al.; Shigella flexneri is the causative agent of bacillary dysentery and is a facultative intracellular pathogen . Its virulence regulon is subject to tight control by several mechanisms involving the products of over 20 genes and an array of environmental signals . The reguIon is carried on a plasmid that is prone to instability and to integration into the chromosome, with associated silencing of the virulence genes . Closely related regulons are found in other species of Shigella and in enteroinvasive Escherichia coli . A wealth of detailed information is now available on the Shigella virulence gene control circuits, and it is becoming clear that these share many features with regulatory systems found in other bacterial pathogens . All of this makes the S . flexneri virulence gene control system a very attractive topic for those interested in the nature of gene regulatory networks in bacteria. J Chemother, 1998 Aug, 10(4), 285 - 90 Prevalence and susceptibility of Shigella species to 11 antibiotics in a Kuwait teaching hospital; Jamal WY et al.; During the 5-year period 1990-1993 and 1996, 202 Shigella spp . were isolated from stool specimens of symptomatic patients of all age groups seen in our hospital . Over these periods the trend of the incidence of shigellosis showed that 18% of the total strains were isolated during the invasion year (1990) followed by an upsurge (24%) during the Gulf War period (1991) and a steady decline in the post-war period, 17% in 1992 and 14% in 1993 . There was another wave of increased isolation rate (27%) during a period of relative calm in the country (1996) studied for comparison . The predominant Shigella species was S . flexneri which accounted for 46% of the 202 isolates, followed by S . sonnei (42%), S . dysenteriae (7%) and S . boydii (5%) . Fifty-four percent of the 202 Shigella isolates were resistant to ampicillin, 56% to trimethoprim/sulfamethoxazole, 35% to chloramphenicol, 13% and 9% to cephalothin and amoxicillin/clavulanic acid respectively . All the isolates were fully susceptible to ciprofloxacin, the aminoglycosides and the second- and third-generation cephalosporins . Eighty-seven (43%) of the 202 isolates were resistant to two or more antibiotics . Of the 87 multiply resistant Shigella spp., 58 (67%) were S . flexneri while 19 (22%) were S . sonnei . Shigella resistance to the first-line antibiotics is a major problem that frequently limits the therapeutic options with orally available active antibiotic therapy. Folia Microbiol (Praha), 1998, 43(3), 305 - 10 Interaction of vaccinia virus with the actin cytoskeleton; Way M; Vaccinia virus infection results in large rearrangements of the host actin cytoskeleton including the formation of actin tails that are strikingly similar to those seen in Listeria, Shigella and Rickettsia infections . Using actin polymerization as the driving force the intracellular enveloped form of the vaccinia virus (IEV) is propelled on the tip of actin tails at a speed of 2.8 microns/min, both intra- and intercellularly . The similarities between the actin-based motility of the vaccinia virus, Listeria, Shigella and Rickettsia suggest that intracellular pathogens have developed a common strategy to exploit the actin cytoskeleton of the host to facilitate their intercellular spread . This review focuses on our current understanding of the interactions between the vaccinia virus and the actin cytoskeleton. Folia Microbiol (Praha), 1998, 43(3), 239 - 46 Molecular and cellular mechanisms of invasion of the intestinal barrier by enteric pathogens . The paradigm of Shigella; Sansonetti PJ; The pathogenesis of bacillary dysentery can be studied at different levels of integration of the cellular components that constitute the colonic mucosal barrier . We considered the interaction of Shigella flexneri in three experimental systems that provide complementary information and a scheme of events occurring in human colorectal mucosa as Shigella invasion proceeds . Interaction of S . flexneri with individual epithelial cells shows a series of events in which the bacterium, upon contact with the cell surface, releases a set of Ipa proteins (i.e . invasins) through a specialized, activable, type-III secretory apparatus (i.e . Mxi/Spa) . Via a complex signaling process, these invasins cause major rearrangements of the subcortical cytoskeletal network which allow bacterial entry by a macropinocytotic event . Then the bacterium lyses its phagocytotic vacuole and initiates intracytoplasmic movement, due to polar assembly of actin filaments caused by a bacterial surface protein, IcsA . This allows very efficient colonization of the host cell cytoplasm and passage to adjacent cells via protrusions which are engulfed by a cadherin-dependent process . However, when invasive Shigella are deposited on the apical side of polarized monolayers of human colonic cells, they appear unable to invade, indicating that bacteria need to reach the subepithelial area to invade the epithelium . In this system, it has been shown that transepithelial signaling caused by apical bacteria induces adherence and transmigration of basal polymorphonuclears (PMN), thus disrupting the monolayer permeability and facilitating bacterial invasion . LPS accounts for a large part of this transepithelial signalization to PMN . Such a process could account for invasion in intestinal crypts . Finally, models of infection, such as the rabbit ligated intestinal loop show that initial bacterial entry occurs essentially via M cells of the follicular associated epithelium . It then causes apoptosis of macrophages located in the follicular dome, inducing release of IL-1 beta which, in turn, initiates inflammation, leading to destabilization of the epithelial structures as modeled above . These data can now be used to understand the mechanisms of mucosal protection against bacillary dysentery. Br J Rheumatol, 1998 Jul, 37(7), 784 - 8 Longitudinal investigation of bacterium-specific synovial lymphocyte proliferation in reactive arthritis and lyme arthritis; Fendler C et al.; BACKGROUND: Antigen-specific lymphocyte proliferation of synovial fluid mononuclear cells (SF MNC) has been reported repeatedly in reactive arthritis and Lyme arthritis; however, less information is available on serial investigations of SF MNC in the same patients . METHODS: In this study, the synovial lymphocyte proliferation to Yersinia, Chlamydia, Shigella and Borrelia burgdorferi was investigated sequentially at different time points in 28 patients with reactive arthritis, undifferentiated oligoarthritis or Lyme arthritis responding to one of these bacteria . RESULTS: The same bacterium was always recognized in arthritis triggered by Chlamydia, Shigella or Borrelia, with much variation in the proliferative response . Only the Yersinia-specific responses changed specificity, suggesting that the proliferative response to Yersinia is non-specific in some patients . CONCLUSIONS: Our data support the concept of a local antigen-specific T-cell response in reactive arthritis or Lyme arthritis but not the concept suggested by others that a switch to an autoimmune response takes place in long-standing disease. Infect Immun, 1998 Sep, 66(9), 4572 - 6 Construction of a stable attenuated Shigella sonnei DeltavirG vaccine strain, WRSS1, and protective efficacy and immunogenicity in the guinea pig keratoconjunctivitis model; Hartman AB et al.; Construction of a stable Shigella sonnei vaccine has been complicated by the instability of the virulence phenotype caused by the spontaneous loss of the invasion plasmid . To select a suitable candidate for vaccine construction, 16 S . sonnei strains were screened for stability of the virulence phenotype . A stable strain, S . sonnei Mosely, was selected for further work . pDeltavirG2, a deletion derivative of the virG gene in the sacB suicide vector pCVD442, was used to generate an S . sonnei virG deletion strain, WRSS1, which was invasive in HeLa cells but negative in the Sereny test . WRSS1 was found to be both immunogenic and protective in the guinea pig keratoconjunctivitis model. Infect Immun, 1998 Sep, 66(9), 4484 - 90 Alteration of HLA-B27 peptide presentation after infection of transfected murine L cells by Shigella flexneri; Boisgerault F et al.; Shigella flexneri is a triggering agent for reactive arthritis in HLA-B27-susceptible individuals . Considering the intracellular multiplication of bacteria, it seems likely that bacterial peptides may be presented by the major histocompatibility complex (MHC) class I pathway . To examine this hypothesis, we infected HLA-B*2705- and/or human beta2-microglobulin-transfected murine L-cell lines with M90T, an invasive strain of S . flexneri . Bacterial infection induced no detectable modifications in the biosynthesis and expression level of HLA-B27, as assessed by immunoprecipitation, Northern blot analysis, and flow cytometry . Using confocal microscopy, we observed that bacterial infection induced a clustering of HLA-B27 molecules during macropinocytosis and before bacterial dissemination from cell to cell . Peptides naturally bound to HLA-B27 molecules were acid eluted from infected cells and separated by high-performance liquid chromatography . Major differences were observed in high-performance liquid chromatography profiles and in the nature of peptides presented following bacterial infection . Although most of the antigens presented were not accessed by Edman degradation, we obtained two sequences partially homologous to bacterial proteins . These peptides lacked the major HLA-B27 peptide anchor (Arg) at position 2, and one had an unusual length of 14 amino acids . These data suggest that alterations in the peptide presentation by HLA-B27 occur during infection, which could be relevant to the pathogenesis of HLA-B27-related arthritis. Infect Immun, 1998 Sep, 66(9), 4237 - 43 Requirement of the Shigella flexneri virulence plasmid in the ability to induce trafficking of neutrophils across polarized monolayers of the intestinal epithelium; McCormick BA et al.; Attachment of an array of enteric pathogens to epithelial surfaces is accompanied by recruitment of polymorphonuclear leukocytes (PMN) across the intestinal epithelium . In this report, we examine how Shigella-intestinal epithelium interactions evoke the mucosal inflammatory response . We modeled these interactions in vitro by using polarized monolayers of the human intestinal epithelial cell line, T84, isolated human PMNs, and Shigella flexneri . We show that Shigella attachment to T84-cell basolateral membranes was a necessary component in the signaling cascade for induction of basolateral-to-apical directed transepithelial PMN migration, the direction of PMN transepithelial migration in vivo . In contrast, attachment of Shigella to the T84-cell apical membrane failed to stimulate a directed PMN transepithelial migration response . Importantly, the ability of Shigella to induce PMN migration across epithelial monolayers was dependent on the presence of the 220-kb virulence plasmid . Moreover, examination of Shigella genes necessary to signal subepithelial neutrophils established the requirement of a functional type III secretion system . Our results indicate that the ability of Shigella to elicit transepithelial signaling to neutrophils from the basolateral membrane of epithelial cells represents a mechanism involved in Shigella-elicited enteritis in humans. FEMS Microbiol Lett, 1998 Aug 1, 165(1), 159 - 65 Characterization of enteroinvasive Escherichia coli and Shigella strains by RAPD analysis; Bando SY et al.; Genetic variation of 33 enteroinvasive Escherichia coli (EIEC), 12 non-EIEC and 39 Shigella strains (representing the 4 species of this genus) was analyzed using the random amplified polymorphic DNA (RAPD) technique . Reproducible polymorphisms were generated and the combined data allowed us to construct a dendrogram using Jaccard's distance . Two main groups were obtained: one for Shigella and the other for EIEC and non-EIEC strains . The first group contained four clusters, one for each Shigella species . The second group contained one cluster for EIEC and another for non-EIEC strains . The main clusters encompassed many small clusters corresponding to different serotypes . It was possible to characterize each one of the 84 strains under study as well as the boundaries among Shigella species and between this genus and EIEC strains. J Clin Microbiol, 1998 Sep, 36(9), 2404 - 7 Study of the relatedness of isolates of Shigella flexneri and Shigella sonnei obtained in 1986 and 1987 and in 1994 and 1995 from Hong Kong; Houang ET et al.; We used pulsed-field gel electrophoresis (PFGE) to study the genetic relatedness of 235 isolates of Shigella flexneri and Shigella sonnei collected in Hong Kong (97 isolates from 1986 and 1987 and 138 isolates from 1994 and 1995) . Altogether, 13 gels were run with bacteriophage lambda ladder DNA (Pharmacia) as an external reference in every sixth lane, standardized reagents and methods, and isolates randomized for species and years . For quantitative illustration of the relationships within a large body of isolates, computer-generated dendrograms were used to determine the number of isolates in pulsotypes at Dice coefficients of similarity of 75% (PT75) and 50% (PT50) . For S . flexneri, there was a significant difference in the distribution of isolates collected during the two periods in both PT75 and PT50, with 68% of isolates collected in 1994 and 1995 sharing a coefficient of similarity of >/=68% . For S . sonnei, a significant difference was observed in PT50 only . We also used Upholt's formula for an approximation of the fraction of nucleotide difference between isolates and Molecular Evolutionary Genetics Analysis to determine relative genetic distances . For both species, the relative genetic distances between isolates of the earlier collection period were significantly greater (P < 0.0001), i . e., they were further apart and therefore more diverse than those of the later period . We conclude that it is possible for a typical clinical laboratory to analyze a large amount of PFGE information on Shigella isolates obtained under controlled conditions . Such data analysis should enhance surveillance capabilities and give indications of further work to be done on various aspects of bacterial pathogenicity of the species. Biochem Biophys Res Commun, 1998 Jul 30, 248(3), 669 - 72 Alterations in high molecular mass penicillin-binding protein 1 associated with beta-lactam resistance in Shigella dysenteriae; Ghosh AS et al.; Beta-lactam resistance poses a major problem in the chemotherapy of shigellosis caused by Shigella dysenteriae . Such resistance may arise from alterations in the affinities or amounts of the penicillin-binding proteins (PBPs) for beta-lactams, elaboration of beta-lactamases and reduced permeability across the outer membrane . The mechanisms of resistance in S . dysenteriae have not been studied in depth . This report describes a laboratory mutant, M19 which was characterized by the appearance of two high molecular mass PBPs of 84 (PBP1') and 82 kDa (PBP1") . M19 was more resistant to cefsulodin and cefoxitin . Resistance could be correlated with lower second order rate constants (k+2/K) of acylation . Moreover there was an overall two-fold increase in the relative amount of PBP1 (i.e . 1' + 1") in the mutant M19 compared to C152 . This is the first report which presents evidence of the involvement of altered high molecular mass PBPs in beta-lactam resistance in S . dysenteriae. Zh Mikrobiol Epidemiol Immunobiol, 1998 May-Jun, (3), 63 - 7 {Genotyping of Shigella flexneri 2a strains isolated from patients with acute dysentery in St . Petersburg}; Stavitskaia EL et al.; Polymerase chain reaction with universal primers (UP-PCR) was used for the genotyping of 76 S.flexneri 2a cultures isolated from patients with acute dysentery in infectious and psychoneurological hospitals of St . Petersburg . 9 types were determined, and each of them included cultures with identical UP-PCR patterns . The population of the infective agent was more heterogeneous in psychoneurological hospitals where the change of types was registered in May-September 1995 . Some of these types were probably epidemic strains . UP-PCR was found to be a promising method increasing the efficiency of traditional epidemiological analysis. Zh Mikrobiol Epidemiol Immunobiol, 1998 May-Jun, (3), 31 - 5 {Interhospital spread of Shigella flexneri 2A}; Kurakin ES; In this article the results of the study of regularities in the development of outbreak morbidity in shigellosis, caused by S.flexneri 2a, in hospitals are presented . The study was carried out with the use of the method of typing by the plasmid profile . The study showed the continuity of the epidemic process in the foci which appeared at intervals considerably exceeding the incubation period . The fact of the interhospital spread of S.flexneri 2a was established . The strain causing the disease was identified by the characteristic set of plasmids and their size . The possibility of reinfection of patients with S.flexneri 2a under hospital conditions was confirmed . The possibility of changes in the main transmission routes in the course of the spread of S.flexneri 2a infection in closed groups was pointed out. J Antimicrob Chemother, 1998 Jul, 42(1), 99 - 102 Increasing frequency of mecillinam-resistant shigella isolates in urban Dhaka and rural Matlab, Bangladesh: a 6 year observation; Hossain MA et al.; A total of 14,915 shigella isolates obtained in 1991-1996 from patients attending the Dhaka (urban) and Matlab (rural) treatment centres of the International Centre for Diarrhoeal Disease Research, Bangladesh were examined for susceptibility to ampicillin, co-trimoxazole, nalidixic acid, mecillinam and ciprofloxacin by a disc diffusion method . There were no ciprofloxacin-resistant shigella isolates . The prevalence of resistance to ampicillin, co-trimoxazole and nalldixic acid varied between isolates . It increased to similar degrees in isolates from both Matlab and Dhaka . However, resistance to mecillinam was more prevalent among isolates from Matlab than from Dhaka . The increase in mecillinam-resistant shigellae in the community may have grave implications for the empirical treatment of shigellosis in Bangladesh and other developing countries. Rev Biol Trop, 1989 Jun, 37(1), 69 - 73 {Aeromonas spp . and Plesiomonas shigelloides in bivalves, mud, and water from the Gulf of Nicoya, Costa Rica}; Rodriguez E et al.; Bivalves, mud, and surface water were collected at three different sites of the Gulf of Nicoya, Costa Rica, in search of Aeromonas spp . and Plesiomonas shigelloides . For their isolation, these bacteria were enriched in alkaline peptone water and streaked on MacConkey agar and on brilliant green bile inositol agar . This was followed by the biochemical tests necessary for their identification . Thirty-five strains of A . hydrophila, 58 of A . caviae, 43 of A . sobria, and 7 of P . shigelloides were isolated . None of these predominated nor was there any indication of a seasonal distribution along the 15 month's duration of the study . Seven strains of A . hydrophila and two of A . sobria showed the biochemical characteristics associated with toxin production (positive Voges-Proskauer and lysine decarboxylase tests) . These species are widely distributed in the gulf and there is risk of contracting an infection while bathing or when eating raw bivalves from this area. J Bacteriol, 1998 Aug, 180(16), 4111 - 5 The tip of the hydrophobic hairpin of colicin U is dispensable for colicin U activity but is important for interaction with the immunity protein; Pilsl H et al.; The hydrophobic C terminus of pore-forming colicins associates with and inserts into the cytoplasmic membrane and is the target of the respective immunity protein . The hydrophobic region of colicin U of Shigella boydii was mutated to identify determinants responsible for recognition of colicin U by the colicin U immunity protein . Deletion of the tip of the hydrophobic hairpin of colicin U resulted in a fully active colicin that was no longer inactivated by the colicin U immunity protein . Replacement of eight amino acids at the tip of the colicin U hairpin by the corresponding amino acids of the related colicin B resulted in colicin U(575-582ColB), which was inactivated by the colicin U immunity protein to 10% of the level of inactivation of the wild-type colicin U . The colicin B immunity protein inactivated colicin U(575-582ColB) to the same degree . These results indicate that the tip of the hydrophobic hairpin of colicin U and of colicin B mainly determines the interaction with the corresponding immunity proteins and is not required for colicin activity . Comparison of these results with published data suggests that interhelical loops and not membrane helices of pore-forming colicins mainly interact with the cognate immunity proteins and that the loops are located in different regions of the A-type and E1-type colicins . The colicin U immunity protein forms four transmembrane segments in the cytoplasmic membrane, and the N and C termini face the cytoplasm. Microbiology, 1998 Jul, 144 ( Pt 7), 1815 - 22 SepA, the 110 kDa protein secreted by Shigella flexneri: two-domain structure and proteolytic activity; Benjelloun-Touimi Z et al.; Shigellosis is characterized by a strong inflammatory response which is induced by bacteria invading the colonic mucosa . Characterization of a sepA mutant indicated that SepA, the major protein secreted by Shigella flexneri growing in laboratory media, might be involved in invasion and destruction of the host intestinal epithelium . The sequence of the first 500 residues of mature SepA (110 kDa) is homologous to that of the N-terminal region of IgA1 proteases . To investigate the potential proteolytic activity of SepA, the activity of the purified protein on a wide range of synthetic peptides was tested . SepA hydrolysed several of these substrates and the activity was inhibited by PMSF . Several peptides which were hydrolysed by SepA have been described as specific substrates for cathepsin G, a serine protease produced by polymorphonuclear leukocytes that was proposed to play a role in inflammation . However, unlike cathepsin G, SepA degraded neither fibronectin nor angiotensin I and had no effect on aggregation of human platelets . In addition, analysis of SepA hydrolysis by proteinase K suggested that the protein is composed of two domains of about 450 residues separated by a hinge region of 100 residues . The 47 kDa N-terminal domain was stable and endowed with proteolytic activity. N Z Med J, 1998 Jun 26, 111(1068), 234 - 5 Antimicrobial resistances among Shigella in New Zealand; Brett MS; AIM: To determine the prevalence of antimicrobial resistances among recent isolates of Shigella in New Zealand . METHOD: A total of 107 Shigella isolates referred to the Institute of Environmental Science and Research from 20 hospital and community laboratories between January and June 1996 were tested by an agar dilution method . RESULTS: Shigella sonnei accounted for 70% of the isolates and S flexneri for 23% . Resistance to ampicillin and cotrimoxazole was detected in 42% and 57% of the isolates respectively, and combined ampicillin and co-trimoxazole resistance occurred in 30.8% of the isolates . The prevalence of cephalothin resistance was 5.6% . Resistance to cefotaxime, ciprofloxacid and gentamicin was not detected and 31.8% were sensitive to all agents tested . Ampicillin resistance was significantly more prevalent in S flexneri than S sonnei . CONCLUSIONS: The high prevalence of ampicillin and cotrimoxazole resistance indicates that ampicillin and cotrimoxazole are no longer useful for empirical treatment of shigellosis in New Zealand . The findings indicate a need to monitor the prevalence of antimicrobial resistances among Shigella and suggest that antimicrobial susceptibility testing might be needed to guide antimicrobial therapy. Kansenshogaku Zasshi, 1998 Jun, 72(6), 615 - 20 {Usefulness of genotypic analysis for investigation of an epidemic of Shigella sonnei infections in Ooami-shirasato Town, Chiba Prefecture}; Uchimura M et al.; In March 1996, an epidemic of Shigella sonnei infection occurred in Ooamishira-sato Town, Chiba Prefecture . Colicine typing, antibiotic resistance patterns, plasmid profiles, pulsed-field gel electrophoresis (PFGE) and random amplified poly-morphic DNA (RAPD) were used for the investigation of the epidemic . Ninety-four isolates from patients exhibited three different colicine types and five different antibiotic resistance patterns . But the patterns of plasmid profile, PFGE and RAPD were uniform among the isolates with different colicine type and antibiotic resistance pattern . It is possible that these isolates belonged to a single bacterial clone and circulated through human to human. Acta Paediatr Jpn, 1998 Jun, 40(3), 259 - 63 Diagnosis of bacterial enteric infections in children in Zambia; Nakano T et al.; BACKGROUND: The bacterial pathogens commonly responsible for diarrhea in children under the age of 5 in Zambia were identified and the most effective methods of diagnosis of such infections in laboratories with limited resources, such as those in developing countries, are recommended . METHODS: Stool samples were collected from children under the age of 5 years who visited the Diarrhoea Training Unit (DTU) of Zambia University Teaching Hospital in Lusaka, Zambia, between May 1992 and May 1993 . A total of 639 children were evaluated for the presence of bacterial infection using standard culture media . The prevalence of bacterial pathogens was compared with that reported from other developing countries . RESULTS: Pathogenic strains of Escherichia coli were isolated from 95 (14.9%) children, Shigella species from 65 (10.2%) children, and Vibrio cholerae from 21 (3.3%) children . The presence of visible blood in the feces was an early indicator of the presence of shigellosis . CONCLUSIONS: E . coli, Shigella species and Vibrio cholerae were the major causes of bacterial diarrhea in the Zambian children studied . Research is required to determine the prevalence of such enteropathogenic strains . The use of adequate diagnostic procedures is indispensable to appropriate management . The recommendations have been prepared as a manual for the identification of enteropathogenic bacteria to be used in laboratories with limited resources, such as in developing countries. Acta Paediatr, 1998 Jun, 87(6), 627 - 30 Nutritional status and diarrhoeal pathogen in hospitalized children in Bangladesh; Dewan N et al.; We studied the relationship between nutritional status and infection due to specific enteropathogens in young children with diarrhoea . Overall, 26% of the children were severely underweight, 27% were severely wasted and 19% were severely stunted . Children with Shigellae and V . cholerae O1 were significantly more severely underweight, wasted and stunted than those with rotavirus diarrhoea (p < 0.0001) . Our results indicate that an effective nutrition programme for young children might have greater impact on diarrhoeal illness caused by Shigella and V . cholerae than by rotavirus diarrhoea. Mol Microbiol, 1998 Jun, 28(6), 1211 - 22 Overexpression and topology of the Shigella flexneri O-antigen polymerase (Rfc/Wzy); Daniels C et al.; Lipopolysaccharides (LPS), particularly the O-antigen component, are one of many virulence determinants necessary for Shigella flexneri pathogenesis . O-antigen biosynthesis is determined mostly by genes located in the rfb region of the chromosome . The rfc/wzy gene encodes the O-antigen polymerase, an integral membrane protein, which polymerizes the O-antigen repeat units of the LPS . The wild-type rfc/wzy gene has no detectable ribosome-binding site (RBS) and four rare codons in the translation initiation region (TIR) . Site-directed mutagenesis of the rare codons at positions 4, 9 and 23 to those corresponding to more abundant tRNAs and introduction of a RBS allowed detection of the rfc/wzy gene product via a T7 promoter/polymerase expression assay . Complementation studies using the rfc/wzy constructs allowed visualization of a novel LPS with unregulated O-antigen chain length distribution, and a modal chain length could be restored by supplying the gene for the O-antigen chain length regulator (Rol/Wzz) on a low-copy-number plasmid . This suggests that the O-antigen chain length distribution is determined by both Rfc/Wzy and Rol/Wzz proteins . The effect on translation of mutating the rare codons was determined using an Rfc::PhoA fusion protein as a reporter . Alkaline phosphatase enzyme assays showed an approximately twofold increase in expression when three of the rare codons were mutated . Analysis of the Rfc/Wzy amino acid sequence using TM-PREDICT indicated that Rfc/Wzy had 10-13 transmembrane segments . The computer prediction models were tested by genetically fusing C-terminal deletions of Rfc/Wzy to alkaline phosphatase and beta-galactosidase . Rfc::PhoA fusion proteins near the amino-terminal end were detected by Coomassie blue staining and Western blotting using anti-PhoA serum . The enzyme activities of cells with the rfc/wzy fusions and the location of the fusions in rfc/wzy indicated that Rfc/Wzy has 12 transmembrane segments with two large periplasmic domains, and that the amino- and carboxy-termini are located on the cytoplasmic face of the membrane. Carbohydr Res, 1998 Mar, 308(1-2), 229 - 38 Measurement of interglycosidic 3JCH coupling constants of selectively 13C labeled oligosaccharides by 2D J-resolved 1H NMR spectroscopy; Pozsgay V et al.; Tri-, tetra-, and penta-saccharide fragments of the O-specific polysaccharide of Shigella dysenteriae type 1 have been prepared in which a D-galactose residue of each oligosaccharide methyl glycoside derivative contains a 13C label at C-1 . The interglycosidic coupling constants (3JCH) of these 13C nuclei with the H-3 nuclei of the adjacent 2-acetamido-2-deoxy-D-glucose residues have been measured by two-dimensional, J-resolved 1H NMR spectroscopy . The magnitudes of these coupling constants indicate that the trisaccharide is conformationally different to the higher oligosaccharide homologs, in agreement with previous studies of 13C chemical shifts and 1JCH values. J Appl Microbiol, 1998 May, 84(5), 709 - 14 Evaluation of the immunospecificity of the porin Om1 of Vibrio anguillarum serotype O1; Simon M et al.; Three methods of immunoanalysis (immunoblot, ELISA and dot-blot) were used to evaluate the immunospecificity of the antiserum against the porin Om1 of Vibrio anguillarum serotype O1 with respect to all the serotypes of V . anguillarum, different Vibrio species and other Gram-negative genera . In the immunoblot analysis of the outer membrane proteins, this antiserum cross-reacted with the main outer membrane protein (MOMP) of all the Vibrio strains studied but not with other genera, except Plesiomonas shigelloides . However, when analyses were performed using whole cells as antigens (ELISA and dot-blot), the antiserum was more specific for V . anguillarum. Infect Immun, 1998 Aug, 66(8), 3918 - 24 Hemolysin-positive enteroaggregative and cell-detaching Escherichia coli strains cause oncosis of human monocyte-derived macrophages and apoptosis of murine J774 cells; Fernandez-Prada C et al.; Infection of human monocyte-derived macrophages (HMDM) and J774 cells (murine macrophage cell line) with several enteroaggregative and cytodetaching Escherichia coli (EAggEC and CDEC, respectively) strains demonstrated that some strains could induce macrophage cell death accompanied by release of lactate dehydrogenase activity and interleukin 1beta (IL-1beta) into culture supernatants . The mode of cell death differed in the two types of macrophages . Damage to macrophage plasma membrane integrity without changes in nuclear morphology resulted in cytolysis of HMDM . This mechanism of cell death has been previously described for virulent Shigella infection of HMDM and is termed oncosis . In contrast, infection of J774 cells by EAggEC and CDEC strains resulted in apoptosis . The presence of alpha-hemolysin (Hly) in EAggEC and CDEC strains appears to be critical for both oncosis in HMDM and apoptosis in J774 cells . Bacteria lacking Hly, including Hly- EAggEC strains as well as enterotoxigenic, enteropathogenic, and enterohemorrhagic E . coli strains, behaved like avirulent Shigella flexneri in that the macrophage monolayers were intact, with no release of lactate dehydrogenase activity or IL-1beta into the culture supernatants. Infect Immun, 1998 Aug, 66(8), 3909 - 17 Inactivation of DsbA, but not DsbC and DsbD, affects the intracellular survival and virulence of Shigella flexneri; Yu J; In this study, three mutants, dsbA::kan, dsbC-kan, and dsbD-kan, of Shigella flexneri serotype 5 were constructed and characterized to investigate the role of the periplasmic thiol:disulfide oxidoreductases in pathogenicity . In gentamicin protection assays and the Sereny test, the dsbA mutant showed reduced virulence while the dsbC and dsbD mutants were similar to the wild type . That inactivation of dsbA was responsible for the reduced virulence was verified by complementation with the cloned wild-type gene in in vitro and in vivo assays . Despite the changed virulence behavior, the dsbA mutant could penetrate HeLa cells 15 min postinfection, consistent with the fact that it actively secretes Ipa proteins upon Congo red induction . Furthermore, the dsbA mutant was able to produce actin comets and protrusions, indicating its capacity for intra- and intercellular spread . However, a kinetic analysis of intracellular growth showed that the dsbA mutant barely grew in HeLa cells during a 4-h infection whereas the wild type had a doubling time of 41 min . Electron microscopy analysis revealed that dsbA mutant bacteria were trapped in protrusion-derived vacuoles surrounded by double membranes, resembling an icsB mutant reported previously . Moreover, the trapped bacteria appeared to be lysed simultaneously with the double membranes, resulting in characteristic empty vacuoles in the host cell cytosol . Thus, the attenuation mechanism for dsbA mutant appears to be more complicated than was previously suggested. J Chemother, 1998 Jun, 10(3), 221 - 4 Transferable trimethoprim resistance in Shigella strains; Yuce A et al.; The susceptibility patterns of 35 Shigella isolates (16 S . flexneri, 14 S . dysenteriae and 5 S . sonnei) to trimethoprim (Tp) and various antibiotics including amoxycillin, amoxycillin-clavulanic acid, nalidixic acid, ciprofloxacin, ceftazidime and ceftriaxone, were investigated . Twenty-two (62.8%) strains were resistant to Tp with a minimal inhibitory concentration (MIC50) value of 512 mg/L . Only six isolates were amoxycillin resistant, to which clavulanic acid restored sensitivity in all of them . None of the isolates were resistant either to extended spectrum cephalosporins or to quinolones . Resistance to Tp was transferred from 7 of the 22 isolates (31.8%) to the recipient Escherichia coli K12 . Tp MIC values of the transconjugants were 512 mg/L . In no strain could amoxycillin resistance be transferred . Our results indicate that as the prevalence of transferable Tp resistance in Shigella isolates in Izmir is substantially high, alternative antimicrobial agents should be considered for empirical antibiotic therapy. Risk Anal, 1998 Jun, 18(3), 309 - 28 Topics in microbial risk assessment: dynamic flow tree process; Marks HM et al.; Microbial risk assessment is emerging as a new discipline in risk assessment . A systematic approach to microbial risk assessment is presented that employs data analysis for developing parsimonious models and accounts formally for the variability and uncertainty of model inputs using analysis of variance and Monte Carlo simulation . The purpose of the paper is to raise and examine issues in conducting microbial risk assessments . The enteric pathogen Escherichia coli O157:H7 was selected as an example for this study due to its significance to public health . The framework for our work is consistent with the risk assessment components described by the National Research Council in 1983 (hazard identification; exposure assessment; dose-response assessment; and risk characterization) . Exposure assessment focuses on hamburgers, cooked a range of temperatures from rare to well done, the latter typical for fast food restaurants . Features of the model include predictive microbiology components that account for random stochastic growth and death of organisms in hamburger . For dose-response modeling, Shigella data from human feeding studies were used as a surrogate for E . coli O157:H7 . Risks were calculated using a threshold model and an alternative nonthreshold model . The 95% probability intervals for risk of illness for product cooked to a given internal temperature spanned five orders of magnitude for these models . The existence of even a small threshold has a dramatic impact on the estimated risk. Infect Dis Clin North Am, 1998 Jun, 12(2), 285 - 303 Travelers' diarrhea . Epidemiology, prevention, and self-treatment; Ericsson CD; Risk factors for travelers' diarrhea include adventurous behavior, consumption of unclean water or food, and special hosts like those taking long acting H2 blockers . Approaches to prevention include education about risk factors, which often fails to lead to modification of risky behavior, and chemoprophylaxis with bismuth subsalicylate-containing compounds or antimicrobial agents . Chemoprophylaxis is generally discouraged except in special circumstances and in high-risk hosts . Self-treatment of travelers' diarrhea is successful in limiting the course of diarrhea and minimizing losses of vacation and business time . Current therapeutic options, in order of increasing effectiveness, include attapulgite, BSS-containing compounds, loperamide, antimicrobial agents such as the fluoroquinolones, and the combination of loperamide and an antimicrobial agent . Under study are a nonabsorbed antimicrobial agent, rifaximin, and a novel calmodulin inhibitor, zaldaride . Development and evaluation of vaccines against enterotoxigenic Escherichia coli and Shigella are proceeding apace but are not yet available for routine use. J Bacteriol, 1998 Jul, 180(14), 3522 - 8 Identification of cpxR as a positive regulator essential for expression of the Shigella sonnei virF gene; Nakayama S et al.; virF is the master regulator which activates the virulence determinant genes of Shigella spp . such as ipaBCD and virG . We previously reported that expression of virF itself is regulated in a pH-dependent manner and that cpxA, a sensor of a two-component regulatory system, is involved in this regulation (S . Nakayama and H . Watanabe, J . Bacteriol . 177:5062-5069, 1995) . Disruption of cpxR, which has been thought to be the cognate response regulator of cpxA (J . Dong, S . Iuchi, H.-S . Kwan, Z . Lue, and E . C . C . Lin, Gene 136:227-230, 1993), abolished virF expression almost completely . Purified CpxR bound directly to the upstream region of virF . Binding capacity was enhanced when CpxR was phosphorylated by coincubation with acetyl phosphate in vitro . Furthermore, we observed that phosphorylated CpxR could activate virF transcription in vitro . These results clearly indicated that CpxR was an essential activator for virF expression and strongly suggested that the binding of phosphorylated CpxR to the target site upstream of the virF gene induced a direct activation of virF transcription. Blood, 1998 Jul 15, 92(2), 558 - 66 Shiga toxin type 1 activates tumor necrosis factor-alpha gene transcription and nuclear translocation of the transcriptional activators nuclear factor-kappaB and activator protein-1; Sakiri R et al.; Shiga toxins (Stxs) produced by Shigella dysenteriae 1 and Escherichia coli have been implicated in the pathogenesis of bloody diarrhea, acute renal failure, and neurologic abnormalities . The pathologic hallmark of Stx-mediated tissue damage is the development of vascular lesions in which endothelial cells are swollen and detached from underlying basement membranes . However, in vitro studies using human vascular endothelial cells demonstrated minimal Stx-induced cytopathic effects, unless the target cells were also incubated with the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1bta) . These cytokines have been shown to upregulate the expression of the Stx-binding membrane glycolipid globotriaosylceramide (Gb3) . We show here that purified Stx1 induces TNF secretion by a human monocytic cell line, THP-1, in a dose- and time-dependent manner . Treatment of cells with both lipopolysaccharides (LPS) and Stx1 results in augmented TNF production . Treatment with the nontoxic Gb3-binding subunit of Stx1 or with an anti-Gb3 monoclonal antibody did not trigger TNF production . Northern blot analyses show that Stx1 causes increased TNF-alpha production through transcriptional activation . Increased levels of TNF-alpha mRNA are preceded by the nuclear translocation of the transcriptional activators NF-kappaB and AP-1 and the loss of cytoplasmic IkappaB-alpha . These data are the first to show that, in addition to direct cytotoxicity, Stxs possess cellular signaling capabilities sufficient to induce the synthesis of cytokines that may be necessary for target cell sensitization and the development of vascular lesions. J R Coll Surg Edinb, 1998 Jun, 43(3), 160 - 2 Surgical lessons learned from the Shigella dysenteriae type I epidemic; Grant HW et al.; An epidemic of Shigella dysenteriae type I is spreading through Africa . It is a particularly infectious and virulent form of dysentery which can cause clinical confusion with other endemic diseases and may present to the surgeon as a result of its complications . A total of 140 children with Shigella dysenteriae type I presented to the paediatricians at King Edward VIII Hospital in 1995; 35 were referred to the surgeons because of abdominal tenderness, distension, peritonitis or perforation . Ten children underwent laparotomy--four for peritonitis and six for perforation . Of the four children with peritonitis, three had transmural colitis . Therefore laparotomy was only performed for objective evidence of perforation . Of the subsequent non-operated group with the clinical features of peritonitis, none developed further surgical problems in the acute phase and none died . It is suggested that surgery in the acute phase should be avoided unless there is evidence of perforation. Biochemistry, 1998 Jun 30, 37(26), 9394 - 8 Shiga toxin attacks bacterial ribosomes as effectively as eucaryotic ribosomes; Suh JK et al.; Several pathogenic bacteria, including Shigelladysenteriae and certain strains of Escherichia coli, produce potent class 2 ribosome inhibiting proteins (RIPs) termed Shiga toxins (Stx) . The toxins are bipartite molecules composed of a single A chain (StxA) noncovalently associated with a pentamer of receptor-binding B subunits (StxB) . StxA and Stx1A from E . coli are protoxins . Proteolysis generates an A1 enzyme (28 kDa) and an A2 fragment (3 kDa), which remain bound, inactivating the enzyme, until a disulfide bond linking them is reduced . Efforts to express active recombinant Stx1A1 in the cytoplasm of E . coli were very difficult and led to the hypothesis that Stx1A1 is toxic to E . coli . We created the gene for a His-tagged Stx1A1 (cStx1A1) and expressed it in E . coli from a tightly controlled expression vector . About 1-2 mg of protein can be purified in a one-step isolation from 1 L of culture . cStx1A1, RTA, and PAP exhibited similar high toxicity against the Artemia ribosomes with IC50 values near 1 nM . Surprisingly, Stx1A1 had an IC50 of 0.8 nM against E . coli ribosomes, about the same as it had for Artemia ribosomes . This is about 250 times more active than PAP against bacterial targets, making Stx1A1 the most powerful RIP toxin presently known against E . coli ribosomes. Kansenshogaku Zasshi, 1998 May, 72(5), 499 - 503 {Shigella dysenteriae strains possessing a new serovar (204/96) isolated from imported diarrheal cases in Japan}; Matsushita S et al.; Five Shigella strains isolated from stool cultures of imported diarrheal cases in Japan, did not react to any antisera of the established Shigella serovars . These strains had the typical biochemical characteristics of Shigella dysenteriae, and were biochemically identical . All strains were positive in the Sereny test and other tests for invasivness; these indicate that they can cause shigellosis in humans . The results of antigenic analysis revealed that they did not belong to any of the recognized or provisional serovars, and were serologically indistinguishable . They had the same drug-resistance pattern (CP.TC.SM.ABPC.ST) and plasmid-profile . Strain 96-204 is designated as the test strain for this new serovar. East Afr Med J, 1998 Mar, 75(3), 160 - 1 Antibiotic sensitivity of endemic Shigella in Mbarara, Uganda; Legros D et al.; We analysed the chimio-sensitivity to antibiotics of endemic strains of Shigella isolated in Mbarara district, southwest Uganda . Twenty four strains were isolated, of which none was sensitive to cotrimoxazole and eight (33.4%, 95% CI {15.6-55.3}) to ampicillin, the two antibiotics recommended to treat dysentery during non epidemic periods in Uganda . Two isolates were resistant to nalidixic acid and none was resistant to the fluoroquinolones (Ciprofloxacin, Norfloxacin) . It is concluded that the results of this survey could be used to facilitate the elaboration of a new treatment protocol to treat endemic dysentery cases in Uganda. Curr Microbiol, 1998 Jul, 37(1), 28 - 31 Incidence of non-01 Vibrio cholerae and Aeromonas spp . in fresh water in Araraquara, Brazil; Pasetto Falcao D et al.; The occurrence of Aeromonas spp., Vibrio cholerae, and Plesiomonas shigelloides in fresh water from various sources in Araraquara, State of Sao Paulo, Brazil was determined . Samples from ten distinct irrigation systems used in vegetable cultivation, from five distinct streams, from two reservoirs, from one artificial lake, and from three distinct springs were analyzed . All isolates were serotyped and tested for hemolysin, cytotoxin, heat-stable (ST) and heat-labile (LT) enterotoxins production; presence of plasmid; autoagglutination and drug resistance . V . cholerae isolates were also tested for cholera enterotoxin (CT) production, and Aeromonas isolates for suicide phenomenon . No P . shigelloides was found . V . cholerae non 01 was found in five irrigation water samples and in three stream samples . Aeromonas sp . were isolated in two samples of irrigation water, in three streams, and in one reservoir . All the V . cholerae and Aeromonas isolates were positive for beta-hemolysin production, and all Aeromonas isolates were positive for suicide phenomenon; cytotoxic activities were observed in two Aeromonas strains . Cholera enterotoxin was not found in eight V . cholerae non-01 isolates tested by the Y-1 mouse adrenal cell . All isolates were also negative for the other virulence markers . V . cholerae isolates were found to be sensitive to the majority of drugs tested, while Aeromonas strains presented multiple drug resistance. Int J Food Microbiol, 1998 May 5, 41(1), 9 - 19 Revised model for aerobic growth of Shigella flexneri to extend the validity of predictions at temperatures between 10 and 19 degrees C; Zaika LL et al.; Although Shigella is a major foodborne pathogen, its growth in foods has received little attention . Growth of S . flexneri 5348 inoculated into commercially available sterile foods (canned broths, meat, fish, UHT milk, baby foods) was studied at 10 to 37 degrees C . S . flexneri was enumerated by surface-plating on Tryptic Soy Agar and growth curves were fitted by means of the Gompertz equation . Observed growth kinetics values and values calculated using a previously developed response surface model compared favorably for growth at 19 to 37 degrees C, but not at < 19 degrees C . To refine the model, additional data were collected for growth at 10 to 19 degrees C . A total of 844 tests in BHI broth, representing 197 variable combinations of temperature (10-37 degrees C), pH (5.0-7.5), NaCl (0.5-5.0%) and NaNO2 (0-1000 ppm) was used for the revised model . The revised model, developed in BHI, gave significantly better agreement of calculated growth kinetics values with those observed in foods at 10 to 19 degrees C. Aust N Z J Ophthalmol, 1998 May, 26(2), 161 - 3 Congenital endophthalmitis following maternal shellfish ingestion; Marshman WE et al.; PURPOSE: To highlight an unusual organism causing a unilateral endophthalmitis by transplacental spread . METHOD: We report a case of Plesiomonas shigelloides endophthalmitis, presenting in a newborn, with co-existing septicaemia and meningitis.There was a significant maternal history of diarrhoea associated with the ingestion of oysters 2 weeks prior to delivery . RESULT: The endophthalmitis was treated with parenteral antibiotics and topical mydriatics with complete resolution, although subsequent assessment of the affected eye suggests a poor visual outcome . CONCLUSION: Endophthalmitis in the newborn is an unusual clinical finding and usually presents with other manifestations of bacteraemia . Plesiomonas shigelloides is fortunately an infrequent cause of neonatal infection, but is associated with a high degree of morbidity and mortality . We postulate that this neonate acquired P . shigelloides via the transplacental route, and suggest that this organism be included in the list of 'other' causes of transplacental infection that has been abbreviated to 'O' in the acronym 'TORCH'. DNA Res, 1998 Feb 28, 5(1), 11 - 4 Identification of the region required for monomerization of the rolling circle plasmid pKYM; Yasukawa H et al.; Plasmid pKYM, isolated from the gram-negative bacterium Shigella sonnei, is a small multicopy plasmid which replicates by a rolling circle mechanism . The formation of multimers has been observed in a derivative of pKYM which lost a part of the origin region, and the loss of the monomerization mechanism would have led to these multimers . By analyzing the constructs of several mutants, we discovered that a DNA region required for monomerization was present upstream of the RepK binding site in the replication origin . As either of the T-rich sequence or the inverted repeat sequences which were seen in that region have been lost in the multimer-forming plasmids, these sequences may be necessary for monomerization. FEMS Microbiol Lett, 1998 May 15, 162(2), 303 - 9 Two highly related regulatory proteins, Shigella flexneri VirF and enterotoxigenic Escherichia coli Rns, have common and distinct regulatory properties; Porter ME et al.; The Rns protein of enterotoxigenic Escherichia coli (ETEC) and the VirF protein of Shigella flexneri are members of the AraC family of transcription regulators . Rns is required for positive activation of the CS1 fimbrial genes, while VirF is a positive regulator of an invasion gene regulon . The amino acid sequences of the proteins are 36% identical, and both proteins activate transcription in response to increases in temperature . Here, we show that Rns is capable of complementing fully a null mutation in the S . flexneri virF gene . However, the VirF protein cannot replace Rns as an activator of CS1 gene expression in ETEC . This failure is not due to the absence from ETEC of a co-factor required by VirF since it also occurs when the CS1 system is moved into an S . flexneri genetic background . Nor is it a function of growth medium composition or a failure in virF gene expression . Instead, these findings point to important differences in the mechanisms by which these related transcription factors regulate gene expression in Gram-negative pathogens. FEMS Microbiol Lett, 1998 May 15, 162(2), 201 - 6 Novel metallo beta-lactamase mediated by a Shigella flexneri plasmid; O'Hara K et al.; Novel carbapenem-hydrolyzing beta-lactamase (newly named MET-1) encoded on a transferable plasmid pMS390 from Shigella flexneri JS19622 was purified . The molecular weight was 28,000 by SDS-PAGE and the isoelectric point was higher than 9.3 . This beta-lactamase favorably hydrolyzed classical cephalosporins and oxyimino-cephalosporins rather than penicillins and carbapenems, but did not hydrolyze monobactams . The enzymatic activity was inhibited by EDTA, and the enzyme was found to contain two moles of zinc per mole of enzyme protein by means of atomic absorption spectrophotometry . These results indicated that the enzyme is a zinc beta-lactamase which differs from known metallo beta-lactamases, especially in its cephalosporinase-type substrate profile. Antimicrob Agents Chemother, 1998 Jun, 42(6), 1476 - 83 Delivery of the non-membrane-permeative antibiotic gentamicin into mammalian cells by using Shigella flexneri membrane vesicles; Kadurugamuwa JL et al.; We developed a model to test whether non-membrane-permeative therapeutic agents such as gentamicin could be delivered into mammalian cells by means of bacterial membrane vesicles . Many gram-negative bacteria bleb off membrane vesicles (MVs) during normal growth, and the quantity of these vesicles can be increased by brief exposure to gentamicin (J . L . Kadurugamuwa and T . J . Beveridge, J . Bacteriol . 177:3998-4008, 1995), which can be entrapped within the MVs . Gentamicin-induced MVs (g-MVs) were isolated from Shigella flexneri and contained 85 +/- 2 ng of gentamicin per microgram of MV protein . Immunogold electron microscopic labeling of thin sections with antibodies specific to S . flexneri lipopolysaccharide (LPS) demonstrated the adherence and subsequent engulfment of MVs by the human Henle 407 intestinal epithelial cell line . Further incubation of g-MVs with S . flexneri-infected Henle cells revealed that the g-MVs penetrated throughout the infected cells and reduced the intracellular pathogen by approximately 1.5 log10 CFU in the first hour of incubation . Antibiotic was detected in the cytoplasms of host cells, indicating the intracellular placement of the drug following the penetration of g-MVs . Soluble antibiotic, added as a fluid to the tissue culture growth medium, had no effect on intracellular bacterial growth, confirming the impermeability of the cell membranes of the tissue to gentamicin . Western blot analysis of MVs with S . flexneri Ipa-specific antibodies demonstrated that the invasion protein antigens IpaB, IpaC, and IpaD were present in MVs . Being bilayered, with outer faces composed of LPS and Ipa proteins, these MVs were readily engulfed by the otherwise impermeable membranes and eventually liberated their contents into the cytoplasmic substance of the host tissue. Microbiol Immunol, 1998, 42(4), 259 - 64 Epidemiologic study of Shigella sonnei from sequential outbreaks and sporadic cases using different typing techniques; Matsumoto M et al.; We noted that eight outbreaks of Shigella sonnei from an unknown source occurred sequentially in Aichi Prefecture, Japan, between October 1992-June 1993 . For comparative purposes we analyzed 53 outbreak-related isolates of Shigella sonnei using different subtyping methods and studied the epidemiology of the outbreaks . It appeared from our study that DNA-based techniques such as plasmid typing and pulsed-field gel electrophoresis (PFGE) were more useful tools for subtyping Shigella sonnei than colicin typing and the antimicrobial susceptibility test . Moreover, according to PFGE analysis, four genetically related isolates of Shigella sonnei were responsible for the eight sequential outbreaks . To further investigate the epidemiology of outbreaks, 58 sporadic isolates of Shigella sonnei from overseas travelers with shigellosis during the same period were also examined . We found that some sporadic isolates from travelers in Asia were genetically related to those of the outbreak-related isolates, indicating that genetically related isolates prevailed in Asia during this period, probably because of the extensive movement of people or food. Kansenshogaku Zasshi, 1998 Apr, 72(4), 365 - 70 {Mechanism of resistance of Shigella flexneri 2a resistant to new quinolone antibiotics}; Oonaka K et al.; A Shigella flexneri 2a strain, which did not respond clinically or in laboratory tests to treatment with new quinolone derivatives, was isolated for the first time in Japan from a patient admitted for diarrhea to a Tokyo hospital . The mechanism of resistance was examined by sequencing the quinolone resistance determining region (QRDR) of the gyrA (a quinolone target enzyme) gene and by comparing the active efflux mechanisms of two strains isolated from this patient (before hospitalization and after tosufloxacin treatment) and one strain isolated from a patient with secondary infection with that of the standard strain ATCC 29903 . DNA sequencing revealed that two amino acid substitutions, namely, Ser (TCG)-83-->Leu (TTG) and Asp (GAC)-87-->Gly (GGC), had occurred in the gyrA of all 3 strains isolated from the patients . Examination of the accumulation of antibiotics in these 3 strains revealed that the strain isol