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1
Bettelheim, Karl A. „Non-O157 Verotoxin-Producing Escherichia coli: A Problem, Paradox, and Paradigm“. Experimental Biology and Medicine 228, Nr. 4 (April 2003): 333–44. http://dx.doi.org/10.1177/153537020322800402.
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The problems associated with identification and characterization of non-O157 verotoxin-producing Escherichia coli (VTEC) are discussed. The paradox of VTEC is that most reports of human illnesses are associated with serotypes such as O157:H7, O111:H– (nonmotile), O26:H11, and O113:H21, which are rarely found in domestic animals. However, those VTEC serotypes commonly found in domestic animals, especially ruminants, rarely cause human illnesses. When they cause human illnesses, the symptoms are similar to those caused by the serotypes E. coli O157:H7, O111:H–, O26:H11, and O113:H21. The impact of VTEC on human and animal health is also addressed. The VTEC and their toxicity are considered as a paradigm for emerging pathogens. The question on how such pathogens could arise from a basic commensal population is also addressed.
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Miko, Angelika, Karin Pries, Sabine Haby, Katja Steege, Nadine Albrecht, Gladys Krause und Lothar Beutin. „Assessment of Shiga Toxin-Producing Escherichia coli Isolates from Wildlife Meat as Potential Pathogens for Humans“. Applied and Environmental Microbiology 75, Nr. 20 (21.08.2009): 6462–70. http://dx.doi.org/10.1128/aem.00904-09.
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ABSTRACT A total of 140 Shiga toxin-producing Escherichia coli (STEC) strains from wildlife meat (deer, wild boar, and hare) isolated in Germany between 1998 and 2006 were characterized with respect to their serotypes and virulence markers associated with human pathogenicity. The strains grouped into 38 serotypes, but eight O groups (21, 146, 128, 113, 22, 88, 6, and 91) and four H types (21, 28, 2, and 8) accounted for 71.4% and 75.7% of all STEC strains from game, respectively. Eighteen of the serotypes, including enterohemorrhagic E. coli (EHEC) O26:[H11] and O103:H2, were previously found to be associated with human illness. Genes linked to high-level virulence for humans (stx 2, stx 2d, and eae) were present in 46 (32.8%) STEC strains from game. Fifty-four STEC isolates from game belonged to serotypes which are frequently found in human patients (O103:H2, O26:H11, O113:H21, O91:H21, O128:H2, O146:H21, and O146:H28). These 54 STEC isolates were compared with 101 STEC isolates belonging to the same serotypes isolated from farm animals, from their food products, and from human patients. Within a given serotype, most STEC strains were similar with respect to their stx genotypes and other virulence attributes, regardless of origin. The 155 STEC strains were analyzed for genetic similarity by XbaI pulsed-field gel electrophoresis. O103:H2, O26:H11, O113:H21, O128:H2, and O146:H28 STEC isolates from game were 85 to 100% similar to STEC isolates of the same strains from human patients. By multilocus sequence typing, game EHEC O103:H2 strains were attributed to a clonal lineage associated with hemorrhagic diseases in humans. The results from our study indicate that game animals represent a reservoir for and a potential source of human pathogenic STEC and EHEC strains.
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Bugarel, Marie, Lothar Beutin und Patrick Fach. „Low-Density Macroarray Targeting Non-Locus of Enterocyte Effacement Effectors (nle Genes) and Major Virulence Factors of Shiga Toxin-Producing Escherichia coli (STEC): a New Approach for Molecular Risk Assessment of STEC Isolates“. Applied and Environmental Microbiology 76, Nr. 1 (30.10.2009): 203–11. http://dx.doi.org/10.1128/aem.01921-09.
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ABSTRACT Rapid and specific detection of Shiga toxin-producing Escherichia coli (STEC) strains with a high level of virulence for humans has become a priority for public health authorities. This study reports on the development of a low-density macroarray for simultaneously testing the genes stx 1, stx 2, eae, and ehxA and six different nle genes issued from genomic islands OI-122 (ent, nleB, and nleE) and OI-71 (nleF, nleH1-2, and nleA). Various strains of E. coli isolated from the environment, food, animals, and healthy children have been compared with clinical isolates of various seropathotypes. The eae gene was detected in all enteropathogenic E. coli (EPEC) strains as well as in enterohemorrhagic E. coli (EHEC) strains, except in EHEC O91:H21 and EHEC O113:H21. The gene ehxA was more prevalent in EHEC (90%) than in STEC (42.66%) strains, in which it was unequally distributed. The nle genes were detected only in some EPEC and EHEC strains but with various distributions, showing that nle genes are strain and/or serotype specific, probably reflecting adaptation of the strains to different hosts or environmental niches. One characteristic nle gene distribution in EHEC O157:[H7], O111:[H8], O26:[H11], O103:H25, O118:[H16], O121:[H19], O5:H−, O55:H7, O123:H11, O172:H25, and O165:H25 was ent/espL2, nleB, nleE, nleF, nleH1-2, nleA. (Brackets indicate genotyping of the flic or rfb genes.) A second nle pattern (ent/espL2, nleB, nleE, nleH1-2) was characteristic of EHEC O103:H2, O145:[H28], O45:H2, and O15:H2. The presence of eae, ent/espL2, nleB, nleE, and nleH1-2 genes is a clear signature of STEC strains with high virulence for humans.
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Luck, Shelley N., Luminita Badea, Vicki Bennett-Wood, Roy Robins-Browne und Elizabeth L. Hartland. „Contribution of FliC to Epithelial Cell Invasion by Enterohemorrhagic Escherichia coli O113:H21“. Infection and Immunity 74, Nr. 12 (18.09.2006): 6999–7004. http://dx.doi.org/10.1128/iai.00435-06.
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ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) O113:H21 can invade epithelial cells. In this study, we found that invasion but not adherence was inhibited by anti-FliCH21 specific antibodies. In addition, deletion of fliCH21 from EHEC O113:H21 resulted in an eightfold decrease in invasion that was restored upon transcomplementation with fliCH21 but not with fliCH6 . These results suggested that FliC plays an important role in the pathogenesis of infections caused by EHEC O113:H21 by allowing bacteria to penetrate the intestinal epithelium.
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Bielaszewska, Martina, Marina Fell, Lilo Greune, Rita Prager, Angelika Fruth, Helmut Tschäpe, M. Alexander Schmidt und Helge Karch. „Characterization of Cytolethal Distending Toxin Genes and Expression in Shiga Toxin-Producing Escherichia coli Strains of Non-O157 Serogroups“. Infection and Immunity 72, Nr. 3 (März 2004): 1812–16. http://dx.doi.org/10.1128/iai.72.3.1812-1816.2004.
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ABSTRACT We identified cytolethal distending toxin and its gene (cdt) in 17 of 340 non-O157 Shiga toxin-producing Escherichia coli (STEC) strains (serotypes O73:H18, O91:H21, O113:H21, and O153:H18), all of which were eae negative. cdt is either chromosomal and homologous to cdt-V (serotypes O73:H18, O91:H21, and O113:H21) or plasmidborne and identical to cdt-III (serotype O153:H18). Among eae-negative STEC, cdt was associated with disease (P = 0.003).
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Paton, Adrienne W., und James C. Paton. „Molecular Characterization of the Locus Encoding Biosynthesis of the Lipopolysaccharide O Antigen of Escherichia coliSerotype O113“. Infection and Immunity 67, Nr. 11 (01.11.1999): 5930–37. http://dx.doi.org/10.1128/iai.67.11.5930-5937.1999.
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ABSTRACT Shiga toxigenic Escherichia coli (STEC) strains are a diverse group of organisms capable of causing severe gastrointestinal disease in humans. Within the STEC family, eae-positive STEC strains, particularly those belonging to serogroups O157 and O111, appear to have greater virulence for humans. However, in spite of beingeae negative, STEC strains belonging to serogroup O113 have frequently been associated with cases of severe STEC disease, including hemolytic-uremic syndrome (HUS). Western blot analysis with convalescent-phase serum from a patient with HUS caused by an O113:H21 STEC strain indicated that human immune responses were directed principally against lipopolysaccharide O antigen. Accordingly, the serum was used to isolate a clone expressing O113 O antigen from a cosmid library of O113:H21 DNA constructed in E. coli K-12. Sequence analysis indicated that the O113 O-antigen biosynthesis (rfb) locus contains a cluster of nine genes which may be cotranscribed. Comparison with sequence databases identified candidate genes for four glycosyl transferases, an O-acetyl transferase, an O-unit flippase, and an O-antigen polymerase, as well as copies of galE and gnd. Two additional, separately transcribed genes downstream of the O113 rfbregion were predicted to encode enzymes involved in synthesis of activated sugar precursors, one of which (designated wbnF) was essential for O113 O-antigen synthesis, and so is clearly a part of the O113 rfb locus. Interestingly, expression of O113 O antigen by E. coli K-12 significantly increased in vitro adherence to both HEp-2 and Henle 407 cells.
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Shen, Songhai, Mariola Mascarenhas, Kris Rahn, James B. Kaper und Mohamed A. Karmal. „Evidence for a Hybrid Genomic Island in Verocytotoxin-Producing Escherichia coli CL3 (Serotype O113:H21) Containing Segments of EDL933 (Serotype O157:H7) O Islands 122 and 48“. Infection and Immunity 72, Nr. 3 (März 2004): 1496–503. http://dx.doi.org/10.1128/iai.72.3.1496-1503.2004.
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ABSTRACT Genomic O island 122 (OI-122) of the verocytotoxin-producing Escherichia coli (VTEC) strain EDL933 contains four putative virulence genes, Z4321, Z4326, Z4332, and Z4333. However, strain CL3 (serotype O113:H21) contains only Z4321, not the other three genes. To determine whether Z4321 is part of a different genomic island in CL3, a region of 27,293 bp up- and downstream of Z4321 was sequenced and found to contain elements of two different EDL933 genomic islands (OI-48 and OI-122) and a Yersinia pestis-like hemolysin/adhesin gene cluster. The region contained OI-48 genes Z1635, Z1636, and Z1637 at the left terminus and Z1641, Z1642, Z1643, and Z1644 at the right. The middle portion consisted of OI-48 gene Z1640, which was separated into three fragments by genomic segments including the Y. pestis cluster and EDL933 OI-122 genes Z4322, Z4321, and Z4318. In a PCR investigation of 36 VTEC strains of different serotypes, intact Z1640 was present in strains of serotypes O157:H7, O26:H11, O103:H2, O111:NM, and O145:NM, which are associated with hemolytic uremic syndrome and outbreaks. In contrast, fragmented Z1640 was seen in strains of nonepidemic serotypes, such as O91:H21 and O113:H21, and in animal serotypes that have not been associated with human disease, indicating that Z1640 might be a virulence gene.
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Luck, Shelley N., Vicki Bennett-Wood, Rachael Poon, Roy M. Robins-Browne und Elizabeth L. Hartland. „Invasion of Epithelial Cells by Locus of Enterocyte Effacement-Negative Enterohemorrhagic Escherichia coli“. Infection and Immunity 73, Nr. 5 (Mai 2005): 3063–71. http://dx.doi.org/10.1128/iai.73.5.3063-3071.2005.
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ABSTRACT The majority of enterohemorrhagic Escherichia coli (EHEC) strains associated with severe disease carry the locus of enterocyte effacement (LEE) pathogenicity island, which encodes the ability to induce attaching and effacing lesions on the host intestinal mucosa. While LEE is essential for colonization of the host in these pathogens, strains of EHEC that do not carry LEE are regularly isolated from patients with severe disease, although little is known about the way these organisms interact with the host epithelium. In this study, we compared the adherence properties of clinical isolates of LEE-negative EHEC with those of LEE-positive EHEC O157:H7. Transmission electron microscopy revealed that LEE-negative EHEC O113:H21 was internalized by Chinese hamster ovary (CHO-K1) epithelial cells and that intracellular bacteria were located within a membrane-bound vacuole. In contrast, EHEC O157:H7 remained extracellular and intimately attached to the epithelial cell surface. Quantitative gentamicin protection assays confirmed that EHEC O113:H21 was invasive and also showed that several other serogroups of LEE-negative EHEC were internalized by CHO-K1 cells. Invasion by EHEC O113:H21 was significantly reduced in the presence of the cytoskeletal inhibitors cytochalasin D and colchicine and the pan-Rho GTPase inhibitor compactin, whereas the tyrosine kinase inhibitor genistein had no significant impact on bacterial invasion. In addition, we found that EHEC O113:H21 was invasive for the human colonic cell lines HCT-8 and Caco-2. Overall these studies suggest that isolates of LEE-negative EHEC may employ a mechanism of host cell invasion to colonize the intestinal mucosa.
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dos Santos, Luis Fernando, Kinue Irino, Tânia Mara Ibelli Vaz und Beatriz Ernestina Cabilio Guth. „Set of virulence genes and genetic relatedness of O113 : H21 Escherichia coli strains isolated from the animal reservoir and human infections in Brazil“. Journal of Medical Microbiology 59, Nr. 6 (01.06.2010): 634–40. http://dx.doi.org/10.1099/jmm.0.015263-0.
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Escherichia coli strains of serotype O113 : H21 are commonly described as belonging to a Shiga toxin (Stx)-producing E. coli (STEC) pathotype worldwide. Albeit this STEC serotype is frequently identified among cattle and other domestic animals, to the best of our knowledge no human infections associated with STEC O113 : H21 have been registered in Brazil to date. Here, we report the virulence profile and genetic relatedness of a collection of O113 : H21 E. coli strains mainly isolated from the animal reservoir aimed at determining their potential as human pathogens. The strains from the animal reservoir (n=34) were all classified as STEC, whereas the few isolates recovered so far from human diarrhoea (n=3) lacked stx genes. Among the STEC, the stx 2d-activatable gene was identified in 85 % of the strains that also carried lpfA O113, iha, saa, ehxA, subAB, astA, cdt-V, espP, espI and epeA; the human strains harboured only lpfA O113, iha and astA. All the strains except one, isolated from cattle, were genetically classified as phylogenetic group B1. High mass plasmids were observed in 25 isolates, but only in the STEC group were these plasmids confirmed as the STEC O113 megaplasmid (pO113). Many closely related subgroups (more than 80 % similarity) were identified by PFGE, with human isolates clustering in a subgroup separate from most of the animal isolates. In conclusion, potentially pathogenic O113 : H21 STEC isolates carrying virulence markers in common with O113 : H21 clones associated with haemolytic uraemic syndrome cases in other regions were demonstrated to occur in the natural reservoir in our settings, and therefore the risk represented by them to public health should be carefully monitored.
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Feng, Peter C. H., Sabine Delannoy, David W. Lacher, Luis Fernando dos Santos, Lothar Beutin, Patrick Fach, Marta Rivas, Elizabeth L. Hartland, Adrienne W. Paton und Beatriz E. C. Guth. „Genetic Diversity and Virulence Potential of Shiga Toxin-Producing Escherichia coli O113:H21 Strains Isolated from Clinical, Environmental, and Food Sources“. Applied and Environmental Microbiology 80, Nr. 15 (23.05.2014): 4757–63. http://dx.doi.org/10.1128/aem.01182-14.
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ABSTRACTShiga toxin-producingEscherichia colistrains of serotype O113:H21 have caused severe human diseases, but they are unusual in that they do not produce adherence factors coded by the locus of enterocyte effacement. Here, a PCR microarray was used to characterize 65 O113:H21 strains isolated from the environment, food, and clinical infections from various countries. In comparison to the pathogenic strains that were implicated in hemolytic-uremic syndrome in Australia, there were no clear differences between the pathogens and the environmental strains with respect to the 41 genetic markers tested. Furthermore, all of the strains carried only Shiga toxin subtypes associated with human infections, suggesting that the environmental strains have the potential to cause disease. Most of the O113:H21 strains were closely related and belonged in the same clonal group (ST-223), but CRISPR analysis showed a great degree of genetic diversity among the O113:H21 strains.
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Blanco, Jorge, Miguel Blanco, Jesus E. Blanco, Azucena Mora, Enrique A. Gonzalez, Maria I. Bernardez, Maria P. Alonso et al. „Verotoxin-Producing Escherichia coli in Spain: Prevalence, Serotypes, and Virulence Genes of O157:H7 and Non-O157 VTEC in Ruminants, Raw Beef Products, and Humans“. Experimental Biology and Medicine 228, Nr. 4 (April 2003): 345–51. http://dx.doi.org/10.1177/153537020322800403.
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In Spain, as in many other countries, verotoxin-producing Escherichia coli (VTEC) strains have been frequently isolated from cattle, sheep, and foods. VTEC strains have caused seven outbreaks in Spain (six caused by E. coli O157:H7 and one by E. coli O111:H– [nonmotile]) in recent years. An analysis of the serotypes indicated serological diversity. Among the strains isolated from humans, serotypes O26:H11, O111:H–, and O157:H7 were found to be more prevalent. The most frequently detected serotypes in cattle were O20:H19, O22:H8, O26:H11, O77:H41, O105:H18, O113:H21, O157:H7, O171:H2, and OUT (O untypeable):H19. Different VTEC serotypes (e.g., O5:H–, O6:H10, O91:H–, O117:H–, O128:H–, O128:H2, O146:H8, O146:H21, O156:H–, and OUT:H21) were found more frequently in sheep. These observations suggest a host serotype specificity for some VTEC. Numerous bovine and ovine VTEC serotypes detected in Spain were associated with human illnesses, confirming that ruminants are important reservoirs of pathogenic VTEC. VTEC can produce one or two toxins (VT1 and VT2) that cause human illnesses. These toxins are different proteins encoded by different genes. Another virulence factor expressed by VTEC is the protein intimin that is responsible for intimate attachment of VTEC and effacing lesions in the intestinal mucosa. This virulence factor is encoded by the chromosomal gene eae. The eae gene was found at a much less frequency in bovine (17%) and ovine (5%) than in human (45%) non-O157 VTEC strains. This may support the evidence that the eae gene contributes significantly to the virulence of human VTEC strains and that many animal non-O157 VTEC strains are less pathogenic to humans.
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Paton, Adrienne W., Matthew C. Woodrow, Robyn M. Doyle, Janice A. Lanser und James C. Paton. „Molecular Characterization of a Shiga ToxigenicEscherichia coli O113:H21 Strain Lacking eaeResponsible for a Cluster of Cases of Hemolytic-Uremic Syndrome“. Journal of Clinical Microbiology 37, Nr. 10 (1999): 3357–61. http://dx.doi.org/10.1128/jcm.37.10.3357-3361.1999.
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Shiga toxigenic Escherichia coli (STEC) strains are a diverse group of organisms capable of causing severe gastrointestinal disease in humans. Within the STEC family, certain strains appear to have greater virulence for humans. STEC strains carryingeae and belonging to serogroup O157 or O111 have been responsible for the vast majority of outbreaks of STEC disease reported to date. Here we describe a STEC O113:H21 strain lackingeae that was responsible for a cluster of three cases of hemolytic-uremic syndrome. This strain produces a single Stx2-related toxin and adheres efficiently to Henle 407 cells.
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Feng, Peter, Sabine Delannoy, David W. Lacher, Joseph M. Bosilevac und Patrick Fach. „Characterization and Virulence Potential of Serogroup O113 Shiga Toxin–Producing Escherichia coli Strains Isolated from Beef and Cattle in the United States“. Journal of Food Protection 80, Nr. 3 (15.02.2017): 383–91. http://dx.doi.org/10.4315/0362-028x.jfp-16-325.
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ABSTRACT Shiga toxin–producing Escherichia coli (STEC) of serotype O113:H21 have caused severe diseases but are unusual in that they do not produce the intimin protein required for adherence to intestinal epithelial cells. Strains of serogroup O113 are one of the most common STEC found in ground beef and beef products in the United States, but their virulence potential is unknown. We used a microarray to characterize 65 O113 strains isolated in the United States from ground beef, beef trim, cattle feces, and fresh spinach. Most were O113:H21 strains, but there were also nine strains of O113:H4 serotype. Although strains within the same serotype had similar profiles for the genes that were tested on the array, the profiles were distinct between the two serotypes, and the strains belonged to different clonal groups. Analysis by clustered regularly interspaced short palindromic repeat analysis showed that O113:H4 strains are conserved genetically, but the O113:H21 strains showed considerable polymorphism and genetic diversity. In comparison to the O113:H21 strains from Australia that were implicated in severe disease, the U.S. isolates showed similar genetic profiles to the known pathogens from Australia, suggesting that these may also have the potential to cause infections.
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Bumunang, Emmanuel W., Collins N. Ateba, Kim Stanford, Yan D. Niu, Y. Wang und Tim A. McAllister. „Activity of Bacteriophage and Complex Tannins against Biofilm-Forming Shiga Toxin-Producing Escherichia coli from Canada and South Africa“. Antibiotics 9, Nr. 5 (15.05.2020): 257. http://dx.doi.org/10.3390/antibiotics9050257.
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Bacteriophages, natural killers of bacteria, and plant secondary metabolites, such as condensed tannins, are potential agents for the control of foodborne pathogens. The first objective of this study evaluated the efficacy of a bacteriophage SA21RB in reducing pre-formed biofilms on stainless-steel produced by two Shiga toxin-producing Escherichia coli (STEC) strains, one from South Africa and the other from Canada. The second objective examined the anti-bacterial and anti-biofilm activity of condensed tannin (CT) from purple prairie clover and phlorotannins (PT) from brown seaweed against these strains. For 24-h-old biofilms, (O113:H21; 6.2 log10 colony-forming units per square centimeter (CFU/cm2) and O154:H10; 5.4 log10 CFU/cm2), 3 h of exposure to phage (1013 plaque-forming units per milliliter (PFU/mL)) reduced (p ≤ 0.05) the number of viable cells attached to stainless-steel coupons by 2.5 and 2.1 log10 CFU/cm2 for O113:H21 and O154:H10, respectively. However, as biofilms matured, the ability of phage to control biofilm formation declined. In biofilms formed for 72 h (O113:H21; 5.4 log10 CFU/cm2 and O154:H10; 7 log10 CFU/cm2), reductions after the same duration of phage treatment were only 0.9 and 1.3 log10 CFU/cm2 for O113:H21 and O154:H10, respectively. Initial screening of CT and PT for anti-bacterial activity by a microplate assay indicated that both STEC strains were less sensitive (p ≤ 0.05) to CT than PT over a concentration range of 25–400 µg/mL. Based on the lower activity of CT (25–400 µg/mL), they were not further examined. Accordingly, PT (50 µg/mL) inhibited (p ≤ 0.05) biofilm formation for up to 24 h of incubation at 22 °C, but this inhibition progressively declined over 72 h for both O154:H10 and O113:H21. Scanning electron microscopy revealed that both SA21RB and PT eliminated 24 h biofilms, but that both strains were able to adhere and form biofilms on stainless-steel coupons at longer incubation times. These findings revealed that phage SA21RB is more effective at disrupting 24 than 72 h biofilms and that PT were able to inhibit biofilm formation of both E. coli O154:H10 and O113:H21 for up to 24 h.
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Seyahian, E. Abril, Gisela Oltra, Federico Ochoa, Santiago Melendi, Ricardo Hermes, James C. Paton, Adrienne W. Paton et al. „Systemic effects of Subtilase cytotoxin produced by Escherichia coli O113:H21“. Toxicon 127 (März 2017): 49–55. http://dx.doi.org/10.1016/j.toxicon.2016.12.014.
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Rogers, Trisha J., James C. Paton, Hui Wang, Ursula M. Talbot und Adrienne W. Paton. „Reduced Virulence of an fliC Mutant of Shiga-Toxigenic Escherichia coli O113:H21“. Infection and Immunity 74, Nr. 3 (März 2006): 1962–66. http://dx.doi.org/10.1128/iai.74.3.1962-1966.2006.
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ABSTRACT The contribution of flagellin to the virulence of the O113:H21 Shiga-toxigenic Escherichia coli (STEC) strain 98NK2 was investigated in the streptomycin-treated mouse model. Groups of mice were challenged with either the wild-type STEC or a fliC deletion derivative thereof. There was no difference in the level of gut colonization by the two strains, but the fliC mutant was significantly less virulent than its parent; the overall survival rates were 43.7% and 81.2%, respectively (P < 0.025). This is the first report of a nontoxic accessory virulence factor contributing to a fatal outcome of STEC infection in this model. Although H21 FliC is known to be a potent inducer of CXC chemokines, including interleukin 8, there was no obvious difference in the recruitment of polymorphonuclear leukocytes to the intestinal epithelium of mice challenged with either strain. However, immunofluorescence microscopy suggested that the fliC mutant was less capable of forming a close association with the colonic epithelium. This may have reduced the uptake of Stx2 by mice infected with the mutant.
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Lima, Paulo Gomes de, Thalita Martins da Silva, Luciana Maria Ramires Esper, Alice Gonçalves Martins Gonzalez und Robson Maia Franco. „Viabilidade de Escherichia coli O153:H25, O113:H21 e O111:H8 (STEC não-O157) produtoras de toxina Shiga em queijo minas frescal“. Ciência Rural 45, Nr. 1 (Januar 2015): 52–57. http://dx.doi.org/10.1590/0103-8478cr20131678.
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A existência de um reservatório animal é de grande importância na transmissão de Escherichia coli, produtora de toxina shiga (STEC) aos humanos. Epidemiologicamente, o sorotipo O157:H7 tem sido o mais envolvido em surtos de doença humana causada por STEC, porém surtos envolvendo STEC não pertencentes ao sorogrupo O157 (STEC não-O157) têm sido descritos. Inúmeros trabalhos constatam uma elevada ocorrência destes microrganismos em fezes de bovinos no Brasil, entretanto, pouco se sabe sobre a transmissão destes aos produtos de origem animal em nosso país. Neste trabalho, foi avaliada a viabilidade de E.coli O153:H25; O113:H21 e O111:H8 em Queijo Minas Frescal (QMF), produzido com inóculos de STEC não O157: H7 e armazenados a 8ºC. Realizaram-se contagens de E. coli e psicrotróficos totais após o processamento do queijo e com intervalos de sete e quinze dias. Foi observado aumento nas contagens de E. coli STEC não O157: H7 e psicrotróficos totais logo após o processamento do QMF, bem como durante o armazenamento a 8ºC, temperatura máxima recomendada pela legislação brasileira. Demonstra-se que, caso haja contaminação da matéria-prima com STEC não O157: H7 (deste estudo), o processamento do QMF não elimina os microrganismos e a temperatura máxima recomendada pela legislação não inibe a multiplicação bacteriana, mantendo-se o risco à população. Reforça-se, portanto, a atenção à qualidade da matéria-prima, das ferramentas de qualidade no campo e na indústria de alimentos para garantir a inocuidade do produto final
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Hornitzky, Michael A., Kim Mercieca, Karl A. Bettelheim und Steven P. Djordjevic. „Bovine Feces from Animals with Gastrointestinal Infections Are a Source of Serologically Diverse Atypical Enteropathogenic Escherichia coli and Shiga Toxin-Producing E. coli Strains That Commonly Possess Intimin“. Applied and Environmental Microbiology 71, Nr. 7 (Juli 2005): 3405–12. http://dx.doi.org/10.1128/aem.71.7.3405-3412.2005.
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ABSTRACT Shiga toxin-producing Escherichia coli (STEC) and enteropathogenic E. coli (EPEC) cells were isolated from 191 fecal samples from cattle with gastrointestinal infections (diagnostic samples) collected in New South Wales, Australia. By using a multiplex PCR, E. coli cells possessing combinations of stx 1, stx 2, eae, and ehxA were detected by a combination of direct culture and enrichment in E. coli (EC) (modified) broth followed by plating on vancomycin-cefixime-cefsulodin blood (BVCC) agar for the presence of enterohemolytic colonies and on sorbitol MacConkey agar for the presence of non-sorbitol-fermenting colonies. The high prevalence of the intimin gene eae was a feature of the STEC (35 [29.2%] of 120 isolates) and contrasted with the low prevalence (9 [0.5%] of 1,692 fecal samples possessed STEC with eae) of this gene among STEC recovered during extensive sampling of feces from healthy slaughter-age cattle in Australia (M. Hornitzky, B. A. Vanselow, K. Walker, K. A. Bettelheim, B. Corney, P. Gill, G. Bailey, and S. P. Djordjevic, Appl. Environ. Microbiol. 68:6439-6445, 2002). Forty-seven STEC serotypes were identified, including O5:H−, O8:H19, O26:H−, O26:H11, O113:H21, O157:H7, O157:H− and Ont:H− which are known to cause severe disease in humans and 23 previously unreported STEC serotypes. Serotypes Ont:H− and O113:H21 represented the two most frequently isolated STEC isolates and were cultured from nine (4.7%) and seven (3.7%) animals, respectively. Fifteen eae-positive E. coli serotypes, considered to represent atypical EPEC, were identified, with O111:H− representing the most prevalent. Using both techniques, STEC cells were cultured from 69 (36.1%) samples and EPEC cells were cultured from 30 (15.7%) samples, including 9 (4.7%) samples which yielded both STEC and EPEC. Culture on BVCC agar following enrichment in EC (modified) broth was the most successful method for the isolation of STEC (24.1% of samples), and direct culture on BVCC agar was the most successful method for the isolation of EPEC (14.1% samples). These studies show that diarrheagenic calves and cattle represent important reservoirs of eae-positive E. coli.
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Pereira, Maria das Graças C., Barbara A. Byrne, Trân B. H. Nguyen, David J. Lewis und E. Robert Atwill. „The occurrence of subtilase-cytotoxin-encoding genes in environmental Escherichia coli isolated from a Northern California estuary“. Canadian Journal of Microbiology 59, Nr. 6 (Juni 2013): 437–41. http://dx.doi.org/10.1139/cjm-2012-0606.
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The presence of subtilase-cytotoxin-encoding genes was determined in 397 environmental Escherichia coli strains isolated from water, suspended solids, and sediments sampled from different hydrological and environmental conditions in a California estuary. A total of 7 strains (1.76%) were found to harbor subtilase-cytotoxin-encoding genes. Using primers targeting subA only, we generated PCR amplicons from 2 strains; while using primers targeting the 3′ end of SubA downstream to the 5′ end of SubB, amplicons of 232 bp were generated from 5 additional strains. The 556 bp subA sequences were almost identical to that in the subtilase-cytotoxin-positive strain ED 591 (98%), while subAB sequences of 2 non-Shiga-toxigenic strains revealed 100% similarity with the Shiga-toxigenic E. coli O113:H21 strain 98NK2 that was isolated from an outbreak of hemolytic uremic syndrome. Additionally, the serogroup O113:H21 was present in this collection of environmental E. coli, and it was found to harbor stx2d, hra1 that encodes the heat resistant agglutinin 1, and a subAB sequence similar to that in the non-Shiga-toxigenic E. coli subtilase cytotoxin strain ED 591. To further understand potential health risks posed by strains encoding SubAB, future epidemiological studies should consider screening isolates for subAB regardless of the presence of Shiga-toxin-encoding genes.
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Doughty, Stephen, Joan Sloan, Vicki Bennett-Wood, Marcus Robertson, Roy M. Robins-Browne und Elizabeth L. Hartland. „Identification of a Novel Fimbrial Gene Cluster Related to Long Polar Fimbriae in Locus of Enterocyte Effacement-Negative Strains of Enterohemorrhagic Escherichia coli“. Infection and Immunity 70, Nr. 12 (Dezember 2002): 6761–69. http://dx.doi.org/10.1128/iai.70.12.6761-6769.2002.
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ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) is a food-borne cause of bloody diarrhea and the hemolytic-uremic syndrome (HUS) in humans. Most strains of EHEC belong to a group of bacterial pathogens that cause distinctive lesions on the host intestine termed attaching-and-effacing (A/E) lesions. A/E strains of EHEC, including the predominant serotype, O157:H7, are responsible for the majority of HUS outbreaks worldwide. However, several serotypes of EHEC are not A/E pathogens because they lack the locus of enterocyte effacement (LEE) pathogenicity island. Nevertheless, such strains have been associated with sporadic cases and small outbreaks of hemorrhagic colitis and HUS. Of these LEE-negative organisms, O113:H21 is one of the most commonly isolated EHEC serotypes in many regions. Clinical isolates of LEE-negative EHEC typically express Shiga toxin 2 and carry an ∼90-kb plasmid that encodes EHEC hemolysin, but in the absence of LEE, little is known about the way in which these pathogens colonize the host intestine. In this study we describe the identification of a novel fimbrial gene cluster related to long polar fimbriae in EHEC O113:H21. This chromosomal region comprises four open reading frames, lpfA to lfpD, and has the same location in the EHEC O113:H21 genome as O island 154 in the prototype EHEC O157:H7 strain, EDL933. In a survey of EHEC of other serotypes, homologues of lpfA O113 were found in 26 of 28 LEE-negative and 8 of 11 non-O157:H7 LEE-positive EHEC strains. Deletion of the putative major fimbrial subunit gene, lpfA, from EHEC O113:H21 resulted in decreased adherence of this strain to epithelial cells, suggesting that lpf O113 may function as an adhesin in LEE-negative isolates of EHEC.
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Ballem, Andressa, Soraia Gonçalves, Isidro Garcia-Meniño, Saskia C. Flament-Simon, Jesús E. Blanco, Conceição Fernandes, Maria José Saavedra et al. „Prevalence and serotypes of Shiga toxin-producing Escherichia coli (STEC) in dairy cattle from Northern Portugal“. PLOS ONE 15, Nr. 12 (31.12.2020): e0244713. http://dx.doi.org/10.1371/journal.pone.0244713.
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The prevalence of Shiga toxin (Stx)-producing Escherichia coli (STEC) was determined by evaluating its presence in faecal samples from 155 heifers, and 254 dairy cows in 21 farms at North of Portugal sampled between December 2017 and June 2019. The prevalence of STEC in heifers (45%) was significantly higher than in lactating cows (16%) (p<0.05, Fisher exact test statistic value is <0.00001). A total of 133 STEC were isolated, 24 (13.8%) carried Shiga-toxin 1 (stx1) genes, 69 (39.7%) carried Shiga-toxin 2 (stx2) genes, and 40 (23%) carried both stx1 and stx2. Intimin (eae) virulence gene was detected in 29 (21.8%) of the isolates. STEC isolates belonged to 72 different O:H serotypes, comprising 40 O serogroups and 23 H types. The most frequent serotypes were O29:H12 (15%) and O113:H21 (5.2%), found in a large number of farms. Two isolates belonged to the highly virulent serotypes associated with human disease O157:H7 and O26:H11. Many other bovine STEC serotypes founded in this work belonged to serotypes previously described as pathogenic to humans. Thus, this study highlights the need for control strategies that can reduce STEC prevalence at the farm level and, thus, prevent food and environmental contamination.
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Herold, Sylvia, James C. Paton und Adrienne W. Paton. „Sab, a Novel Autotransporter of Locus of Enterocyte Effacement-Negative Shiga-Toxigenic Escherichia coli O113:H21, Contributes to Adherence and Biofilm Formation“. Infection and Immunity 77, Nr. 8 (01.06.2009): 3234–43. http://dx.doi.org/10.1128/iai.00031-09.
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ABSTRACT Shiga-toxigenic Escherichia coli (STEC) strains cause serious gastrointestinal disease, which can lead to potentially life-threatening systemic complications such as hemolytic-uremic syndrome. Although the production of Shiga toxin has been considered to be the main virulence trait of STEC for many years, the capacity to colonize the host intestinal epithelium is a crucial step in pathogenesis. In this study, we have characterized a novel megaplasmid-encoded outer membrane protein in locus of enterocyte effacement (LEE)-negative O113:H21 STEC strain 98NK2, termed Sab (for STEC autotransporter [AT] contributing to biofilm formation). The 4,296-bp sab gene encodes a 1,431-amino-acid protein with the features of members of the AT protein family. When expressed in E. coli JM109, Sab contributed to the diffuse adherence to human epithelial (HEp-2) cells and promoted biofilm formation on polystyrene surfaces. A 98NK2 sab deletion mutant was also defective in biofilm formation relative to its otherwise isogenic wild-type parent, and this was complemented by transformation with a sab-carrying plasmid. Interestingly, an unrelated O113:H21 STEC isolate that had a naturally occurring deletion in sab was similarly defective in biofilm formation. PCR analysis indicated that sab is present in LEE-negative STEC strains belonging to serotypes/groups O113:H21, O23, and O82:H8. These findings raise the possibility that Sab may contribute to colonization in a subset of LEE-negative STEC strains.
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MASANA, M. O., B. A. D'ASTEK, P. M. PALLADINO, L. GALLI, L. L. DEL CASTILLO, C. CARBONARI, G. A. LEOTTA, E. VILACOBA, K. IRINO und M. RIVAS. „Genotypic Characterization of Non-O157 Shiga Toxin–Producing Escherichia coli in Beef Abattoirs of Argentina“. Journal of Food Protection 74, Nr. 12 (01.12.2011): 2008–17. http://dx.doi.org/10.4315/0362-028x.jfp-11-189.
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The non-O157 Shiga toxin–producing Escherichia coli (STEC) contamination in carcasses and feces of 811 bovines in nine beef abattoirs from Argentina was analyzed during a period of 17 months. The feces of 181 (22.3%) bovines were positive for non-O157 STEC, while 73 (9.0%) of the carcasses showed non-O157 STEC contamination. Non-O157 STEC strains isolated from feces (227) and carcasses (80) were characterized. The main serotypes identified were O178:H19, O8:H19, O130:H11, and O113:H21, all of which have produced sporadic cases of hemolytic-uremic syndrome in Argentina and worldwide. Twenty-two (7.2%) strains carried a fully virulent stx/eae/ehxA genotype. Among them, strains of serotypes O103:[H2], O145:NM, and O111:NM represented 4.8% of the isolates. XbaI pulsed-field gel electrophoresis pattern analysis showed 234 different patterns, with 76 strains grouped in 30 clusters. Nine of the clusters grouped strains isolated from feces and from carcasses of the same or different bovines in a lot, while three clusters were comprised of strains distributed in more than one abattoir. Patterns AREXSX01.0157, AREXBX01.0015, and AREXPX01.0013 were identified as 100% compatible with the patterns of one strain isolated from a hemolytic-uremic syndrome case and two strains previously isolated from beef medallions, included in the Argentine PulseNet Database. In this survey, 4.8% (39 of 811) of the bovine carcasses appeared to be contaminated with non-O157 STEC strains potentially capable of producing sporadic human disease, and a lower proportion (0.25%) with strains able to produce outbreaks of severe disease.
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Hussein, Hussein S., und Stanley T. Omaye. „Introduction to the Food Safety Concerns of Verotoxin-Producing Escherichia coli“. Experimental Biology and Medicine 228, Nr. 4 (April 2003): 331–32. http://dx.doi.org/10.1177/153537020322800401.
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Verotoxin-producing Escherichia coli (VTEC) have emerged in the past two decades as food-borne pathogens that can cause major outbreaks of human illnesses worldwide. The number of outbreaks has increased in recent years due to changes in food production and processing systems, eating habits, microbial adaptation, and methods of VTEC transmission. The human illnesses range from mild diarrhea to hemolytic uremic syndrome (HUS) that can lead to death. The VTEC outbreaks have been attributed to O157:H7 and non-O157:H7 serotypes of E. coli. These E. coli serotypes include motile (e.g., O26:H11 and O104:H21) and nonmotile (e.g., O111:H–,0145:H–, and O157:H–) strains. In the United States, E. coli O157:H7 has been the major cause of VTEC outbreaks. Worldwide, however, non-O157:H7 VTEC (e.g., members of the 026, O103, O111, O118, O145, and O166 serogroups) have caused approximately 30% of the HUS cases in the past decade. Because large numbers of the VTEC outbreaks have been attributed to consumption of ruminant products (e.g., ground beef), cattle and sheep are considered reservoirs of these food-borne pathogens. Because of the food safety concern of VTEC, a global perspective on this problem is addressed (Exp Biol Med Vol. 228, No. 4). The first objective was to evaluate the known non-O157:H7 VTEC strains and the limitations associated with their detection and characterization. The second objective was to identify the VTEC serotypes associated with outbreaks of human illnesses and to provide critical evaluation of their virulence. The third objective was to determine the rumen effect on survival of E. coli O157:H7 as a VTEC model. The fourth objective was to explore the role of intimins in promoting attaching and effacing lesions in humans. Finally, the ability of VTEC to cause persistent infections in cattle was evaluated.
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Dytoc, M. T., A. Ismaili, D. J. Philpott, R. Soni, J. L. Brunton und P. M. Sherman. „Distinct binding properties of eaeA-negative verocytotoxin-producing Escherichia coli of serotype O113:H21.“ Infection and Immunity 62, Nr. 8 (1994): 3494–505. http://dx.doi.org/10.1128/iai.62.8.3494-3505.1994.
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Pradel, Nathalie, Valérie Livrelli, Christophe De Champs, Jean-Bernard Palcoux, Alain Reynaud, Flemming Scheutz, Jacques Sirot, Bernard Joly und Christiane Forestier. „Prevalence and Characterization of Shiga Toxin-Producing Escherichia coli Isolated from Cattle, Food, and Children during a One-Year Prospective Study in France“. Journal of Clinical Microbiology 38, Nr. 3 (2000): 1023–31. http://dx.doi.org/10.1128/jcm.38.3.1023-1031.2000.
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During a 1-year survey of Shiga toxin-producing Escherichia coli (STEC) prevalence in central France, 2,143 samples were investigated by PCR for Shiga toxin-encoding genes. A total of 330 (70%) of 471 fecal samples collected from healthy cattle at the Clermont-Ferrand slaughterhouse, 47 (11%) of 411 beef samples, 60 (10%) of 603 cheese samples, and 19 (3%) of 658 stool specimens from hospitalized children with and without diarrhea were positive for thestx gene(s). A STEC strain was isolated from 34% (162 of 471) of bovine feces, 4% (16 of 411) of beef samples, 1% (5 of 603) of cheese samples, and 1.5% (10 of 658) of stool specimens. Of the 220 STEC strains isolated, 34 (15%) harbored thestx 1 gene, 116 (53%) harbored thestx 2 gene, and 70 (32%) carried both thestx 1 and stx 2 genes. However, 32 (14.5%) were not cytotoxic for Vero cells. Theeae gene, found in 12 (5%) of the 220 strains, was significantly associated with the stx 1 gene and with isolates from children. Sequences homologous to ehxAwere found in 102 (46%) of the 220 strains. Thirteen serotypes, OX3:H2, O113:H21, O113:H4, OX3:H21, O6:H10, OX178:H19, O171:H2, O46:H38, O172:H21, O22:H16, O91:H10, O91:H21, and O22:H8, accounted for 102 (55%) of 186 typeable isolates, and only one strain (0.5% of the 186 STEC isolates from cattle), belonged to the O157:H7 serotype. We showed that the majority of the STEC isolates from cattle, beef, and cheese were not likely to be pathogenic for humans and that the STEC strains isolated from children in this study were probably not responsible for diarrheal disease. Finally, the strains associated with hemolytic-uremic syndrome in the same geographical area were shown to belong to particular subsets of the STEC population found in the bovine reservoir.
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Beutin, Lothar, Angelika Miko, Gladys Krause, Karin Pries, Sabine Haby, Katja Steege und Nadine Albrecht. „Identification of Human-Pathogenic Strains of Shiga Toxin-Producing Escherichia coli from Food by a Combination of Serotyping and Molecular Typing of Shiga Toxin Genes“. Applied and Environmental Microbiology 73, Nr. 15 (08.06.2007): 4769–75. http://dx.doi.org/10.1128/aem.00873-07.
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ABSTRACT We examined 219 Shiga toxin-producing Escherichia coli (STEC) strains from meat, milk, and cheese samples collected in Germany between 2005 and 2006. All strains were investigated for their serotypes and for genetic variants of Shiga toxins 1 and 2 (Stx1 and Stx2). stx 1 or variant genes were detected in 88 (40.2%) strains and stx 2 and variants in 177 (80.8%) strains. Typing of stx genes was performed by stx-specific PCRs and by analysis of restriction fragment length polymorphisms (RFLP) of PCR products. Major genotypes of the Stx1 (stx 1, stx 1c, and stx 1d) and the Stx2 (stx 2, stx 2d, stx 2-O118, stx 2e, and stx 2g) families were detected, and multiple types of stx genes coexisted frequently in STEC strains. Only 1.8% of the STEC strains from food belonged to the classical enterohemorrhagic E. coli (EHEC) types O26:H11, O103:H2, and O157:H7, and only 5.0% of the STEC strains from food were positive for the eae gene, which is a virulence trait of classical EHEC. In contrast, 95 (43.4%) of the food-borne STEC strains carried stx 2 and/or mucus-activatable stx 2d genes, an indicator for potential high virulence of STEC for humans. Most of these strains belonged to serotypes associated with severe illness in humans, such as O22:H8, O91:H21, O113:H21, O174:H2, and O174:H21. stx 2 and stx 2d STEC strains were found frequently in milk and beef products. Other stx types were associated more frequently with pork (stx 2e), lamb, and wildlife meat (stx 1c). The combination of serotyping and stx genotyping was found useful for identification and for assignment of food-borne STEC to groups with potential lower and higher levels of virulence for humans.
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Hauser, Elisabeth, Alexander Mellmann, Torsten Semmler, Helen Stoeber, Lothar H. Wieler, Helge Karch, Nikole Kuebler et al. „Phylogenetic and Molecular Analysis of Food-Borne Shiga Toxin-Producing Escherichia coli“. Applied and Environmental Microbiology 79, Nr. 8 (15.02.2013): 2731–40. http://dx.doi.org/10.1128/aem.03552-12.
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ABSTRACTSeventy-five food-associated Shiga toxin-producingEscherichia coli(STEC) strains were analyzed by molecular and phylogenetic methods to describe their pathogenic potential. The presence of the locus of proteolysis activity (LPA), the chromosomal pathogenicity island (PAI) PAI ICL3, and the autotransporter-encoding genesabAwas examined by PCR. Furthermore, the occupation of the chromosomal integration sites of the locus of enterocyte effacement (LEE),selC,pheU, andpheV, as well as the Stx phage integration sitesyehV,yecE,wrbA,z2577, andssrA, was analyzed. Moreover, the antibiotic resistance phenotypes of all STEC strains were determined. Multilocus sequence typing (MLST) was performed, and sequence types (STs) and sequence type complexes (STCs) were compared with those of 42 hemolytic-uremic syndrome (HUS)-associated enterohemorrhagicE. coli(HUSEC) strains. Besides 59 STs and 4 STCs, three larger clusters were defined in this strain collection. Clusters A and C consist mostly of highly pathogeniceae-positive HUSEC strains and some related food-borne STEC strains. A member of a new O26 HUS-associated clone and the 2011 outbreak strainE. coliO104:H4 were found in cluster A. Cluster B comprises onlyeae-negative food-borne STEC strains as well as mainlyeae-negative HUSEC strains. Although food-borne strains of cluster B were not clearly associated with disease, serotypes of important pathogens, such as O91:H21 and O113:H21, were in this cluster and closely related to the food-borne strains. Clonal analysis demonstrated eight closely related genetic groups of food-borne STEC and HUSEC strains that shared the same ST and were similar in their virulence gene composition. These groups should be considered with respect to their potential for human infection.
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Montero, David, Paz Orellana, Daniela Gutiérrez, Daniela Araya, Juan Carlos Salazar, Valeria Prado, Ángel Oñate, Felipe del Canto und Roberto Vidal. „Immunoproteomic Analysis To Identify Shiga Toxin-Producing Escherichia coli Outer Membrane Proteins Expressed during Human Infection“. Infection and Immunity 82, Nr. 11 (25.08.2014): 4767–77. http://dx.doi.org/10.1128/iai.02030-14.
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ABSTRACTShiga-toxin producingEscherichia coli(STEC) is the etiologic agent of acute diarrhea, dysentery, and hemolytic-uremic syndrome (HUS). There is no approved vaccine for STEC infection in humans, and antibiotic use is contraindicated, as it promotes Shiga toxin production. In order to identify STEC-associated antigens and immunogenic proteins, outer membrane proteins (OMPs) were extracted from STEC O26:H11, O103, O113:H21, and O157:H7 strains, and commensalE. colistrain HS was used as a control. SDS-PAGE, two-dimensional-PAGE analysis, Western blot assays using sera from pediatric HUS patients and controls, and matrix-assisted laser desorption ionization–tandem time of flight analyses were used to identify 12 immunogenic OMPs, some of which were not reactive with control sera. Importantly, seven of these proteins have not been previously reported to be immunogenic in STEC strains. Among these seven proteins, OmpT and Cah displayed IgG and IgA reactivity with sera from HUS patients. Genes encoding these two proteins were present in a majority of STEC strains. Knowledge of the antigens produced during infection of the host and the immune response to those antigens will be important for future vaccine development.
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Feng, Peter C. H., und Shanker Reddy. „Prevalences of Shiga Toxin Subtypes and Selected Other Virulence Factors among Shiga-Toxigenic Escherichia coli Strains Isolated from Fresh Produce“. Applied and Environmental Microbiology 79, Nr. 22 (30.08.2013): 6917–23. http://dx.doi.org/10.1128/aem.02455-13.
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ABSTRACTShiga-toxigenicEscherichia coli(STEC) strains were isolated from a variety of fresh produce, but mostly from spinach, with an estimated prevalence rate of 0.5%. A panel of 132 produce STEC strains were characterized for the presence of virulence and putative virulence factor genes and for Shiga toxin subtypes. About 9% of the isolates were found to have theeaegene, which encodes the intimin binding protein, and most of these belonged to known pathogenic STEC serotypes, such as O157:H7 and O26:H11, or to serotypes that reportedly have caused human illness. Among theeae-negative strains, there were three O113:H21 strains and one O91:H21 strain, which historically have been implicated in illness and therefore may be of concern as well. TheehxAgene, which encodes enterohemolysin, was found in ∼60% of the isolates, and thesaaandsubABgenes, which encode STEC agglutinating adhesin and subtilase cytotoxin, respectively, were found in ∼30% of the isolates. However, the precise roles of these three putative virulence factors in STEC pathogenesis have not yet been fully established. Thestx1aandstx2asubtypes were present in 22% and 56%, respectively, of the strains overall and were the most common subtypes among produce STEC strains. Thestx2dsubtype was the second most common subtype (28% overall), followed bystx2c(7.5%), and only 2 to 3% of the produce STEC strains had thestx2eandstx2gsubtypes. Almost half of the produce STEC strains had only partial serotypes or were untyped, and most of those that were identified belonged to unremarkable serotypes. Considering the uncertainties of some of these Stx subtypes and putative virulence factors in causing human illness, it is difficult to determine the health risk of many of these produce STEC strains.
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Bando, Iamashita, Silva, Costa, Abe, Bertonha, Guth, Fujita und Moreira-Filho. „Dynamic Gene Network Analysis of Caco-2 Cell Response to Shiga Toxin-Producing Escherichia coli-Associated Hemolytic–Uremic Syndrome“. Microorganisms 7, Nr. 7 (08.07.2019): 195. http://dx.doi.org/10.3390/microorganisms7070195.
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Shiga toxin-producing Escherichia coli (STEC) O113:H21 strains are associated with human diarrhea and some strains may cause hemolytic–uremic syndrome (HUS). In Brazil, these strains are commonly found in cattle but, so far, were not isolated from HUS patients. Here, a system biology approach was used to investigate the differential transcriptomic and phenotypic responses of enterocyte-like Caco-2 cells to two STEC O113:H21 strains with similar virulence factor profiles (i.e. expressing stx2, ehxA, epeA, espA, iha, saa, sab, and subA): EH41 (Caco-2/EH41), isolated from a HUS patient in Australia, and Ec472/01 (Caco-2/Ec472), isolated from bovine feces in Brazil, during a 3 h period of bacteria–enterocyte interaction. Gene co-expression network analysis for Caco-2/EH41 revealed a quite abrupt pattern of topological variation along 3 h of enterocyte–bacteria interaction when compared with networks obtained for Caco-2/Ec472. Transcriptional module characterization revealed that EH41 induces inflammatory and apoptotic responses in Caco-2 cells just after the first hour of enterocyte–bacteria interaction, whereas the response to Ec472/01 is associated with cytoskeleton organization at the first hour, followed by the expression of immune response modulators. Scanning electron microscopy showed more intense microvilli destruction in Caco-2 cells exposed to EH41 when compared to those exposed to Ec472/01. Altogether, these results show that EH41 expresses virulence genes, inducing a distinctive host cell response, and is likely associated with severe pathogenicity.
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Gerhardt, Elizabeth, Mariana Masso, Adrienne W. Paton, James C. Paton, Elsa Zotta und Cristina Ibarra. „Inhibition of Water Absorption and Selective Damage to Human Colonic Mucosa Are Induced by Subtilase Cytotoxin Produced by Escherichia coli O113:H21“. Infection and Immunity 81, Nr. 8 (03.06.2013): 2931–37. http://dx.doi.org/10.1128/iai.00287-13.
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ABSTRACTShiga toxin-producingEscherichia coliO157:H7 (STEC) is by far the most prevalent serotype associated with hemolytic uremic syndrome (HUS) although many non-O157 STEC strains have been also isolated from patients with HUS. The main virulence factor of STEC is the Shiga toxin type 2 (Stx2) present in O157 and non-O157 strains. Recently, another toxin, named subtilase cytotoxin (SubAB), has been isolated from several non-O157 strains and may contribute to the pathogenesis of HUS. Here, we have demonstrated that an O113:H21 STEC strain expressing SubAB and Stx2 inhibits normal water absorption across human colon and causes damage to the surface epithelium, necrosis, mononuclear inflammatory infiltration, edema, and marked mucin depletion. This damage was less marked, but nevertheless significant, when purified SubAB orE. coliO113:H21 expressing only SubAB was assayed. This is the first study showing that SubAB may directly participate in the mechanisms of diarrhea in children infected with non-O157 STEC strains.
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Rogers, Trisha J., Cheleste M. Thorpe, Adrienne W. Paton und James C. Paton. „Role of Lipid Rafts and Flagellin in Invasion of Colonic Epithelial Cells by Shiga-Toxigenic Escherichia coli O113:H21“. Infection and Immunity 80, Nr. 8 (11.06.2012): 2858–67. http://dx.doi.org/10.1128/iai.00336-12.
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ABSTRACTShiga-toxigenicEscherichia coli(STEC) O113:H21 strains that lack the locus of enterocyte effacement (LEE) efficiently invade eukaryotic cellsin vitro, unlike LEE-positive O157:H7 strains. We used afliCdeletion mutant of the O113:H21 STEC strain 98NK2 (98NK2ΔfliC) to show that invasion of colonic epithelial (HCT-8) cells is heavily dependent on production of flagellin, even though adherence to the cells was actually enhanced in the mutant. Flagellin binds and signals through Toll-like receptor 5 (TLR5), but there was no evidence that either TLR5, the adaptor protein myeloid differentiation primary response gene 88 (MyD88), or the serine kinase interleukin-1 receptor-associated kinase (IRAK) were required for invasion of HCT-8 cells by strain 98NK2, as judged by transfection, RNA knockdown, or inhibitor studies. However, pretreatment of cells with anti-asialo-GM1 significantly decreased 98NK2 invasion (by 40.8%), while neuraminidase treatment (which cleaves terminal sialic acid residues, thus converting GM1 into asialo-GM1) significantly increased invasion (by 70.7%). Pretreatment of HCT-8 cells with either the cholesterol-depleting agent methyl-β-cyclodextrin (MβCD) or the tyrosine kinase inhibitor genistein significantly decreased invasion by 98NK2, indicating a potential role for lipid rafts in the invasion mechanism. Confocal microscopy also showed invading 98NK2 colocalized with lipid raft markers caveolin-1 and GM1. Interestingly, anti-asialo-GM1, neuraminidase, MβCD, and genistein have similar effects on the vestigial level of STEC invasion seen for STEC strain 98NK2ΔfliC, indicating that lipid rafts mediate a common step in flagellin-dependent and flagellin-independent cellular invasion.
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Cicuta, M. E., N. L. Deza, W. R. Roibón, O. R. Arzú und M. C. Barceló. „Escherichia coli productor de toxina Shiga en carnes molidas y chacinados embutidos de Corrientes, Argentina“. Revista Veterinaria 20, Nr. 1 (01.01.2009): 11. http://dx.doi.org/10.30972/vet.2011875.
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<p>Escherichia coli productor de toxina Shiga (STEC) causa casos esporádicos y brotes de diarrea con o sin sangre y síndrome urémico hemolítico. El serotipo O157:H7 es prevalente, pero existen otros serotipos como O26:H11; O103:H2;O111:NM; O121:H19 y O145:NM asociados a enfermedad humana severa. Los rumiantes en general y el ganado vacuno en particular, han sido señalados como los principales reservorios de STEC, y los alimentos de origen cárnico como el vehículo más frecuente. Entre octubre de 2006 y noviembre de 2008 se analizaron bacteriológicamente 246 muestras (206 de carne molida bovina y 40 de chacinados embutidos). Luego de la caracterización bioquímica de las colonias de E. coli se realizó la técnica de PCR múltiple, para detección de los genes stx1/stx2 y rfbO157. La caracterización genotípica de los factores de virulencia accesorios eae y exhA también se realizó por PCR. Se identificaron 172 cepas E. coli (139 de 88 muestras de carne molida y 33 de 19 embutidos); sólo en una muestra de carne molida se aisló E. coli STEC O174:H21, stx2, eae negativo y exhA positivo, sensible a los antibióticos ensayados. A partir de una muestra de carne molida también se detectó una cepa O157:NM no toxigénica siendo sus factores de virulencia accesorios eae y ehxA negativos. Cepas stx2 como la de este trabajo, han sido predominantes en varios estudios llevados a cabo en Argentina sobre bovinos y sus productos, en especial carnes molidas y hamburguesas.</p>
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Paton, Adrienne W., Potjanee Srimanote, Matthew C. Woodrow und James C. Paton. „Characterization of Saa, a Novel Autoagglutinating Adhesin Produced by Locus of Enterocyte Effacement-Negative Shiga-ToxigenicEscherichia coli Strains That Are Virulent for Humans“. Infection and Immunity 69, Nr. 11 (01.11.2001): 6999–7009. http://dx.doi.org/10.1128/iai.69.11.6999-7009.2001.
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ABSTRACT The capacity of Shiga toxigenic Escherichia coli(STEC) to adhere to the intestinal mucosa undoubtedly contributes to pathogenesis of human disease. The majority of STEC strains isolated from severe cases produce attaching and effacing lesions on the intestinal mucosa, a property mediated by the locus of enterocyte effacement (LEE) pathogenicity island. This element is not essential for pathogenesis, as some cases of severe disease, including hemolytic uremic syndrome (HUS), are caused by LEE-negative STEC strains, but the mechanism whereby these adhere to the intestinal mucosa is not understood. We have isolated a gene from the megaplasmid of a LEE-negative O113:H21 STEC strain (98NK2) responsible for an outbreak of HUS, which encodes an auto-agglutinating adhesin designated Saa (STEC autoagglutinating adhesin). Introduction of saacloned in pBC results in a 9.7-fold increase in adherence of E. coli JM109 to HEp-2 cells and a semilocalized adherence pattern. Mutagenesis of saa in 98NK2, or curing the wild-type strain of its megaplasmid, resulted in a significant reduction in adherence. Homologues of saa were found in several unrelated LEE-negative STEC serotypes, including O48:H21 (strain 94CR) and O91:H21 (strain B2F1), which were also isolated from patients with HUS. Saa exhibits a low degree of similarity (25% amino acid [aa] identity) with YadA of Yersinia enterocolitica and Eib, a recently described phage-encoded immunoglobulin binding protein fromE. coli. Saa produced by 98NK2 is 516 aa long and includes four copies of a 37-aa direct repeat sequence. Interestingly, Saa produced by other STEC strains ranges in size from 460 to 534 aa as a consequence of variation in the number of repeats and/or other insertions or deletions immediately proximal to the repeat domain.
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Rogers, Trisha J., Adrienne W. Paton, Shaun R. McColl und James C. Paton. „Enhanced CXC Chemokine Responses of Human Colonic Epithelial Cells to Locus of Enterocyte Effacement-Negative Shiga-Toxigenic Escherichia coli“. Infection and Immunity 71, Nr. 10 (Oktober 2003): 5623–32. http://dx.doi.org/10.1128/iai.71.10.5623-5632.2003.
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ABSTRACT There is increasing evidence that by facilitating translocation of Shiga toxin (Stx) across the intestinal epithelium and by transporting bound toxin to remote sites such as the renal endothelium, polymorphonuclear leukocytes (PMNs) play a key role in the pathogenesis of Shiga-toxigenic Escherichia coli (STEC) disease. Plasma levels of PMN-attracting CXC chemokines such as interleukin-8 (IL-8) also appear to correlate in humans with the severity of disease. Thus, the capacity of STEC strains to elicit CXC chemokine responses in intestinal epithelial cells may be a crucial step in pathogenesis. Accordingly, we attempted to determine which STEC factors are responsible for CXC chemokine induction in human colonic epithelial cells. Infection of Hct-8 cells with locus for enterocyte effacement (LEE)-negative STEC strains isolated from patients with severe STEC disease resulted in up-regulation of IL-8, macrophage inflammatory protein 2α (MIP-2α), MIP-2β, and ENA-78 mRNA significantly higher and earlier than that elicited by several LEE-positive STEC strains, including the O157:H7 strain EDL933. Similarly, levels of IL-8 protein in LEE-negative STEC-infected Hct-8 culture supernatants were significantly higher than in LEE-positive STEC-infected culture supernatants. The difference in responses could not be attributed to the expression or nonexpression of LEE genes, the presence or absence of an STEC megaplasmid, or differences in O serogroups or in the type or amount of Stx produced. Interestingly, however, several of the LEE-negative STEC strains eliciting the strongest chemokine responses belonged to flagellar serotype H21. Incubation of Hct-8 cells with isolated H21 flagellin elicited IL-8 and MIP-2α responses similar to those seen in the presence of the most potent LEE-negative STEC strains. Deletion of the fliC gene, but not the stx 2 gene, largely abolished the capacity of O113:H21 LEE-negative STEC strain 98NK2 to elicit IL-8 and MIP-2α responses in Hct-8 cells. Taken together, these data suggest that although Stx is capable of inducing CXC chemokine responses, the elevated responses seen in cells infected with certain STEC strains are largely attributable to the production of flagellin.
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Srimanote, Potjanee, Adrienne W. Paton und James C. Paton. „Characterization of a Novel Type IV Pilus Locus Encoded on the Large Plasmid of Locus of Enterocyte Effacement-Negative Shiga-Toxigenic Escherichia coli Strains That Are Virulent for Humans“. Infection and Immunity 70, Nr. 6 (Juni 2002): 3094–100. http://dx.doi.org/10.1128/iai.70.6.3094-3100.2002.
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ABSTRACT The majority of Shiga-toxigenic Escherichia coli (STEC) strains isolated from humans with gastrointestinal disease carry large (approximately 90-kb) plasmids. We have been analyzing the megaplasmid (designated pO113) from an O113:H21 STEC strain (98NK2). This strain lacks the locus for enterocyte effacement (LEE) and yet was responsible for an outbreak of hemolytic uremic syndrome. In the present study, we demonstrate that pO113 carries a novel type IV pilus biosynthesis locus (pil) related to those of the IncI plasmids R721, R64, and ColIb9. The pO113 pil locus consists of 11 closely linked genes (pilL through pilV) with an additional separately transcribed upstream gene (pilI). It directs the expression of long thin pili on the 98NK2 surface and the hemagglutination of guinea pig erythrocytes. We also demonstrate that pO113 can be transferred by conjugation. However, the type IV pilus encoded by pO113 does not appear to be involved in the adherence of 98NK2 to HEp-2 or Hct-8 cells in vitro. Homologues of the pO113 pil locus were present in several other LEE-negative STEC strains but not in LEE-positive STEC strains belonging to serogroup O26, O111, or O157.
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Paton, Adrienne W., Potjanee Srimanote, Ursula M. Talbot, Hui Wang und James C. Paton. „A New Family of Potent AB5 Cytotoxins Produced by Shiga Toxigenic Escherichia coli“. Journal of Experimental Medicine 200, Nr. 1 (28.06.2004): 35–46. http://dx.doi.org/10.1084/jem.20040392.
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The Shiga toxigenic Escherichia coli (STEC) O113:H21 strain 98NK2, which was responsible for an outbreak of hemolytic uremic syndrome, secretes a highly potent and lethal subtilase cytotoxin that is unrelated to any bacterial toxin described to date. It is the prototype of a new family of AB5 toxins, comprising a single 35-kilodalton (kD) A subunit and a pentamer of 13-kD B subunits. The A subunit is a subtilase-like serine protease distantly related to the BA_2875 gene product of Bacillus anthracis. The B subunit is related to a putative exported protein from Yersinia pestis, and binds to a mimic of the ganglioside GM2. Subtilase cytotoxin is encoded by two closely linked, cotranscribed genes (subA and subB), which, in strain 98NK2, are located on a large, conjugative virulence plasmid. Homologues of the genes are present in 32 out of 68 other STEC strains tested. Intraperitoneal injection of purified subtilase cytotoxin was fatal for mice and resulted in extensive microvascular thrombosis, as well as necrosis in the brain, kidneys, and liver. Oral challenge of mice with E. coli K-12–expressing cloned subA and subB resulted in dramatic weight loss. These findings suggest that the toxin may contribute to the pathogenesis of human disease.
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Gilmour, Matthew W., Adam B. Olson, Ashleigh K. Andrysiak, Lai-King Ng und Linda Chui. „Sequence-based typing of genetic targets encoded outside of the O-antigen gene cluster is indicative of Shiga toxin-producing Escherichia coli serogroup lineages“. Journal of Medical Microbiology 56, Nr. 5 (01.05.2007): 620–28. http://dx.doi.org/10.1099/jmm.0.47053-0.
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Serogroup classifications based upon the O-somatic antigen of Shiga toxin-producing Escherichia coli (STEC) provide significant epidemiological information on clinical isolates. Each O-antigen determinant is encoded by a unique cluster of genes present between the gnd and galF chromosomal genes. Alternatively, serogroup-specific polymorphisms might be encoded in loci that are encoded outside of the O-antigen gene cluster. Segments of the core bacterial loci mdh, gnd, gcl, ppk, metA, ftsZ, relA and metG for 30 O26 STEC strains have previously been sequenced, and comparative analyses to O157 distinguished these two serogroups. To screen these loci for serogroup-specific traits within a broader range of clinically significant serogroups, DNA sequences were obtained for 19 strains of 10 additional STEC serogroups. Unique alleles were observed at the gnd locus for each examined STEC serogroup, and this correlation persisted when comparative analyses were extended to 144 gnd sequences from 26 O-serogroups (comprising 42 O : H-serotypes). These included O157, O121, O103, O26, O5 : non-motile (NM), O145 : NM, O113 : H21, O111 : NM and O117 : H7 STEC; and furthermore, non-toxin encoding O157, O26, O55, O6 and O117 strains encoded distinct gnd alleles compared to STEC strains of the same serogroup. DNA sequencing of a 643 bp region of gnd was, therefore, sufficient to minimally determine the O-antigen of STEC through molecular means, and the location of gnd next to the O-antigen gene cluster offered additional support for the co-inheritance of these determinants. The gnd DNA sequence-based serogrouping method could improve the typing capabilities for STEC in clinical laboratories, and was used successfully to characterize O121 : H19, O26 : H11 and O177 : NM clinical isolates prior to serological confirmation during outbreak investigations.
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Dallman, T., G. P. Smith, B. O'Brien, M. A. Chattaway, D. Finlay, K. A. Grant und C. Jenkins. „Characterization of a Verocytotoxin-Producing Enteroaggregative Escherichia coli Serogroup O111:H21 Strain Associated with a Household Outbreak in Northern Ireland“. Journal of Clinical Microbiology 50, Nr. 12 (03.10.2012): 4116–19. http://dx.doi.org/10.1128/jcm.02047-12.
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Herold, Sylvia, James C. Paton, Potjanee Srimanote und Adrienne W. Paton. „Differential effects of short-chain fatty acids and iron on expression of iha in Shiga-toxigenic Escherichia coli“. Microbiology 155, Nr. 11 (01.11.2009): 3554–63. http://dx.doi.org/10.1099/mic.0.029454-0.
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Shiga-toxigenic Escherichia coli (STEC) colonizing the bowel are exposed to a variety of short-chain fatty acids (SCFAs), including acetate, propionate and butyrate, produced by gut microflora. However, the total concentrations and relative amounts of SCFAs in the lumen vary with intestinal niche. Here we report that conditions simulating SCFA concentrations present in the human gut trigger expression of the iha gene, which encodes an adherence-conferring outer-membrane protein of pathogenic E. coli. We show that growth under conditions simulating colonic, but not ileal, SCFA concentrations increases iha expression in three tested STEC strains, with the strongest expression detected in LEE-negative STEC O113:H21 strain 98NK2. Expression of iha is known to be subject to Fur-mediated iron repression in O157:H7 STEC, and the same occurs in 98NK2. However, exogenous iron did not repress iha expression in the presence of colonic SCFAs in either 98NK2 or the O157:H7 strain EDL933. Moreover, exposure to the iron chelator 2,2′-dipyridyl caused no further enhancement of iha expression over that induced by colonic SCFAs. These findings indicate that SCFAs regulate iha expression in STEC independently of iron. Increased expression of iha under colonic but not ileal SCFA conditions possibly may contribute to preferential colonization of the human colon by STEC.
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Girardeau, Jean Pierre, Yolande Bertin und Christine Martin. „Genomic analysis of the PAI ICL3 locus in pathogenic LEE-negative Shiga toxin-producing Escherichia coli and Citrobacter rodentium“. Microbiology 155, Nr. 4 (01.04.2009): 1016–27. http://dx.doi.org/10.1099/mic.0.026807-0.
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Shiga toxin-producing Escherichia coli (STEC) causes a spectrum of human illnesses such as haemorrhagic colitis and haemolytic–uraemic syndrome. Although the locus of enterocyte effacement (LEE) seems to confer enhanced virulence, LEE-negative STEC strains are also associated with severe human disease, suggesting that other unknown factors enhance the virulence potential of STEC strains. A novel hybrid pathogenicity island, termed PAI ICL3, has been previously characterized in the LEE-negative O113 : H21 STEC strain CL3. Screening for the presence of PAI ICL3 elements in 469 strains of E. coli, including attaching and effacing (A/E) pathogens [enteropathogenic E. coli (EPEC) and enterohaemorrhagic E. coli (EHEC)], non-A/E pathogens [LEE-negative STEC, extra-intestinal pathogenic E. coli (ExPEC), enterotoxigenic E. coli (ETEC) and enteroaggregative E. coli (EAEC)] and commensal E. coli isolates, showed that PAI ICL3 is unique to LEE-negative STEC strains linked to disease, providing a new marker for these strains. We also showed that a PAI ICL3-equivalent gene cluster is present in the genome of Citrobacter rodentium, on a 53 kb genomic island inserted into the pheV tRNA locus. While the C. rodentium PAI ICL3 shows high similarities at the nucleotide level and in organization with the E. coli PAI ICL3, the genetic context of the integration differs completely. In addition, blast searches revealed that other E. coli pathotypes (O157 : H7 EHEC, ExPEC, EPEC and EAEC) possess incomplete PAI ICL3 elements that contain only the genes located at the extremities of the island. Six of the 16 sequenced E. coli genomes showed deleted PAI ICL3 gene clusters which are carried on mobile genetic elements inserted into pheV, selC or serW tRNA loci, which is compatible with the idea that the PAI ICL3 gene cluster entered E. coli and C. rodentium at multiple times through independent events. The phylogenetic distribution of the PAI ICL3 variants suggests that a B1 genetic background is necessary for the maintenance of the full complement of PAI ICL3 genes in E. coli.
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Newton, Hayley J., Joan Sloan, Vicki Bennett-Wood, Louise M. Adams, Roy M. Robins-Browne und Elizabeth L. Hartland. „Contribution of Long Polar Fimbriae to the Virulence of Rabbit-Specific Enteropathogenic Escherichia coli“. Infection and Immunity 72, Nr. 3 (März 2004): 1230–39. http://dx.doi.org/10.1128/iai.72.3.1230-1239.2004.
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ABSTRACT Enteropathogenic Escherichia coli (EPEC) is a major of cause of diarrhea among children in developing countries. Although EPEC is a human specific pathogen, some related strains are natural pathogens of animals, including laboratory-bred rabbits. We have identified two chromosomal loci in rabbit-specific EPEC (REPEC) O15:H− strain 83/39, which are predicted to encode long polar fimbriae (LPF). lpfR154 was identical to a fimbrial gene cluster, lpfO113 , identified previously in enterohemorrhagic E. coli (EHEC) O113:H21. The second locus, lpfR141 , comprised a novel sequence with five predicted open reading frames, lpfA to lpfE, that encoded long fine fimbriae in nonfimbriated E. coli ORN103. The predicted products of lpfR141 shared identity with components of the lpfABCC′DE gene cluster from EHEC O157:H7, and the fimbriae were similar in morphology and length to LPF from EHEC O157:H7. Interruption of lpfR141 resulted in significant attenuation of REPEC 83/39 for rabbits with respect to the early stages of colonization and severity of diarrhea. However, there was no significant difference in the number of bacteria shed at later time points or in overall body weight and mortality rate of rabbits infected with lpfR141 mutant strains or wild-type REPEC 83/39. Although rabbits infected with the lpfR141 mutants did not develop severe diarrhea, there was evidence of attaching and effacing histopathology, which was indistinguishable in morphology, location, and extent compared to rabbits infected with wild-type REPEC 83/39. The results suggested that lpfR141 contributes to the early stages of REPEC-mediated disease and that this is important for the development of severe diarrhea in susceptible animals.
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ATALLA, HEBA NASHED, ROGER JOHNSON, SCOTT MCEWEN, R. W. USBORNE und C. L. GYLES. „Use of a Shiga Toxin (Stx)-Enzyme-Linked Immunosorbent Assay and Immunoblot for Detection and Isolation of Stx-Producing Escherichia coli from Naturally Contaminated Beef“. Journal of Food Protection 63, Nr. 9 (01.09.2000): 1167–72. http://dx.doi.org/10.4315/0362-028x-63.9.1167.
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The purpose of this study was to evaluate an enzyme-linked immunosorbent assay (ELISA) and an immunoblot procedure for detection and isolation of Shiga toxin-producing Escherichia coli (STEC) from beef, and to correlate the presence of STEC in beef with E. coli and total coliform counts. A total of 120 samples of boneless beef supplied to a meat processor in southern Ontario were tested for the presence of STEC, E. coli, and total coliforms. Following enrichment in modified tryptic soy broth, samples were screened for Shiga toxin (Stx) by a Stx-ELISA and a Vero cell assay (VCA). Samples that were positive in the Stx-ELISA were subjected to the Stx-immunoblot for STEC isolation. Overall, 33.3% of samples were positive in the VCA, and 34.2% were positive in the Stx-ELISA. There was almost complete agreement between the Stx-ELISA and the VCA results (kappa = 0.98). The sensitivity and specificity of the Stx-ELISA with respect to the VCA were 100% and 98.75%, respectively. STEC were isolated by the Stx-immunoblot from 87.8% of the samples that were positive in the Stx-ELISA. The STEC isolates belonged to 19 serotypes, with serotype O113:H21 accounting for 10 of 41 isolates. No STEC of serotype O157:H7 were isolated. There was a significant correlation between E. coli counts and total coliform counts (Spearman correlation coefficient = 0.68, P < 0.01). The E. coli count was positively correlated with detection of STEC by both the Stx-ELISA and the VCA (P < 0.01).
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Paton, Adrienne W., Austen Y. Chen, Hui Wang, Lauren J. McAllister, Florian Höggerl, Ulrike Beate Mayr, Lucy K. Shewell et al. „Protection against Shiga-Toxigenic Escherichia coli by Non-Genetically Modified Organism Receptor Mimic Bacterial Ghosts“. Infection and Immunity 83, Nr. 9 (22.06.2015): 3526–33. http://dx.doi.org/10.1128/iai.00669-15.
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Shiga-toxigenicEscherichia coli(STEC) causes severe gastrointestinal infections in humans that may lead to life-threatening systemic sequelae, such as the hemolytic uremic syndrome (HUS). Rapid diagnosis of STEC infection early in the course of disease opens a window of opportunity for therapeutic intervention, for example, by administration of agents that neutralize Shiga toxin (Stx) in the gut lumen. We previously developed a recombinant bacterium that expresses a mimic of the Stx receptor globotriaosyl ceramide (Gb3) on its surface through modification of the lipopolysaccharide (A. W. Paton, R. Morona, and J. C. Paton, Nat Med6:265–270, 2000,http://dx.doi.org/10.1038/73111). This construct was highly efficaciousin vivo, protecting mice from otherwise fatal STEC disease, but the fact that it is a genetically modified organism (GMO) has been a barrier to clinical development. In the present study, we have overcome this issue by development of Gb3 receptor mimic bacterial ghosts (BGs) that are not classified as GMOs. Gb3-BGs neutralized Stx1 and Stx2in vitrowith high efficiency, whereas alternative Gb3-expressing non-GMO subbacterial particles (minicells and outer membrane blebs) were ineffective. Gb3-BGs were highly efficacious in a murine model of STEC disease. All mice (10/10) treated with Gb3-BGs survived challenge with a highly virulent O113:H21 STEC strain and showed no pathological signs of renal injury. In contrast, 6/10 mice treated with control BGs succumbed to STEC challenge, and survivors exhibited significant weight loss, neutrophilia, and histopathological evidence of renal damage. Thus, Gb3-BGs offer a non-GMO approach to treatment of STEC infection in humans, particularly in an outbreak setting.
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Imuta, Naoko, Tadasuke Ooka, Kazuko Seto, Ryuji Kawahara, Toyoyasu Koriyama, Tsuyoshi Kojyo, Atsushi Iguchi et al. „Phylogenetic Analysis of Enteroaggregative Escherichia coli (EAEC) Isolates from Japan Reveals Emergence of CTX-M-14-Producing EAEC O25:H4 Clones Related to Sequence Type 131“. Journal of Clinical Microbiology 54, Nr. 8 (01.06.2016): 2128–34. http://dx.doi.org/10.1128/jcm.00711-16.
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EnteroaggregativeEscherichia coli(EAEC) causes acute or persistent diarrhea. TheaggRgene is widely used as a marker for typical EAEC. The heterogeneity of EAEC is well known; however, there are few reports on the phylogenetic relationships of EAEC. Recently, CTX-M extended-spectrum β-lactamase (ESBL)-producing EAEC strains have been reported worldwide. To characterize EAEC strains in Japan, we investigated the population structure of EAEC. A total of 167aggR-positive strains isolated from stool specimens from diarrheal patients in Kagoshima (139 strains) and Osaka (28 strains), Japan, between 1992 and 2010 were examined for the prevalence of EAEC virulence markers, theblaCTX-Mgene, and the capacity to form biofilms. Multilocus sequence typing was also conducted. EAEC strains were widely distributed across four majorE. coliphylogroups. Strains of O111:H21/clonal group 40 (CG40) (30 strains), O126:H27/CG200 (13 strains), and O86a:H27/CG3570 (11 strains) in phylogroup B1 are the historical EAEC clones in Japan, and they exhibited strong biofilm formation. Twenty-nine strains of EAEC O25:H4/CG131 were identified in phylogroup B2, 79% of which produced CTX-M-14. This clone has emerged since 2003. The clone harbored plasmid-encoded EAEC virulence genes but not chromosomal virulence genes and had lower biofilm-forming capacity than historical EAEC strains. This clone most likely emerged from a pandemic uropathogenic O25:H4/sequence type 131 clone by acquiring an EAEC virulence plasmid from canonical EAEC. Surveillance of the horizontal transfer of both virulence and ESBL genes amongE. colistrains is important for preventing a worldwide increase in antimicrobial drug resistance.
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Goldwater, P. N., N. Giles und K. A. Bettelheim. „An unusual case of microangiopathic haemolytic anaemia associated with enterohaemorrhagic Escherichia coli O113:H21 infection, a verocytotoxin-2/shiga toxin-2 producing serotype“. Journal of Infection 37, Nr. 3 (November 1998): 302–4. http://dx.doi.org/10.1016/s0163-4453(98)92324-6.
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Leyton, Denisse L., Joan Sloan, Rebecca E. Hill, Steven Doughty und Elizabeth L. Hartland. „Transfer Region of pO113 from Enterohemorrhagic Escherichia coli: Similarity with R64 and Identification of a Novel Plasmid-Encoded Autotransporter, EpeA“. Infection and Immunity 71, Nr. 11 (November 2003): 6307–19. http://dx.doi.org/10.1128/iai.71.11.6307-6319.2003.
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ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) is a prominent, food-borne cause of diarrhea, bloody diarrhea, and the hemolytic uremic syndrome in industrialized countries. Most strains of EHEC carry the locus for enterocyte effacement (LEE) pathogenicity island, but a proportion of isolates from patients with severe disease do not carry LEE and very little is known about virulence factors in these organisms. LEE-negative strains of EHEC typically express Shiga toxin 2 and carry a large plasmid that encodes the production of EHEC hemolysin. In this study, we determined the nucleotide sequence of the transfer region of pO113, the large hemolysin plasmid from LEE-negative EHEC O113:H21 (EH41). This 63.9-kb region showed a high degree of similarity with the transfer region of R64, and pO113 was capable of self-transmission at low frequencies. Unlike R64 and the related dot/icm system of Legionella pneumophila, however, pO113 was unable to mobilize RSF1010. In addition, the pO113 transfer region encoded a novel high-molecular-weight serine protease autotransporter of Enterobacteriaceae (SPATE) protein, termed EpeA. Like other SPATEs, EpeA exhibited protease activity and mucinase activity, but expression was not associated with a cytopathic effect on epithelial cells. Analysis of a second high-molecular-weight secreted protein revealed that pO113 also encodes EspP, a cytopathic SPATE identified previously in EHEC O157:H7. The nucleotide sequences encoding the predicted β-domains of espP and epeA were identical and also shared significant homology with a third SPATE protein, EspI. Both espP and epeA were detected in several LEE-negative clinical isolates of EHEC and thus may contribute to the pathogenesis of this subset of EHEC.
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Jandu, Narveen, Peter J. M. Ceponis, Seiichi Kato, Jason D. Riff, Derek M. McKay und Philip M. Sherman. „Conditioned Medium from Enterohemorrhagic Escherichia coli-Infected T84 Cells Inhibits Signal Transducer and Activator of Transcription 1 Activation by Gamma Interferon“. Infection and Immunity 74, Nr. 3 (März 2006): 1809–18. http://dx.doi.org/10.1128/iai.74.3.1809-1818.2006.
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ABSTRACT Gamma interferon (IFN-γ) is a cytokine important to host defense which can signal through signal transducer and activator of transcription 1 (Stat1). Enterohemorrhagic Escherichia coli (EHEC) modulates host cell signal transduction to establish infection, and EHEC serotypes O113:H21 and O157:H7 both inhibit IFN-γ-induced Stat1 tyrosine phosphorylation in vitro. The aim of this study was to delineate both bacterial and host cell factors involved in the inhibition of Stat1 tyrosine phosphorylation. Human T84 colonic epithelial cells were challenged with direct infection, viable EHEC separated from T84 cells by a filter, sodium orthovanadate, isolated flagellin, bacterial culture supernatants, and conditioned medium treated with proteinase K, trypsin, or heat inactivation. Epithelial cells were then stimulated with IFN-γ and protein extracts were analyzed by immunoblotting. The data showed that IFN-γ-inducible Stat1 tyrosine phosphorylation was inhibited when EHEC adhered to T84 cells, but not by bacterial culture supernatants or bacteria separated from the epithelial monolayer. Conditioned medium from T84 cells infected with EHEC O157:H7 suppressed Stat1 activation, and this was not reversed by treatment with proteinases or heat inactivation. Use of pharmacological inhibitors showed that time-dependent bacterial, but not epithelial, protein synthesis was involved. Stat1 inhibition was also independent of bacterial flagellin, host proteasome activity, and protein tyrosine phosphatases. Infection led to altered IFN-γ receptor domain 1 subcellular distribution and decreased expression in cholesterol-enriched membrane microdomains. Thus, suppression of host cell IFN-γ signaling by production of a contact-dependent, soluble EHEC factor may represent a novel mechanism for this pathogen to evade the host immune system.
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Shen, Songhai, Mariola Mascarenhas, Kris Rahn, James B. Kaper und Mohamed A. Karmali. „Evidence for a Hybrid Genomic Island in Verocytotoxin-Producing Escherichia coli CL3 (Serotype O113:H21) Containing Segments of EDL933 (Serotype O157:H7) O Islands 122 and 48“. Infection and Immunity 72, Nr. 7 (Juli 2004): 4330. http://dx.doi.org/10.1128/iai.72.7.4330.2004.
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