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Enteropathogenic E. Coli (enteropathogenic + e._coli)
Selected AbstractsDetection and distribution of probiotic Escherichia coli Nissle 1917 clones in swine herds in GermanyJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2006S. Kleta Abstract Aims:, To verify the presence of Escherichia coli Nissle 1917 as a natural isolate in swine and to characterize in vitro probiotic properties as well as in vivo persistence in a feeding experiment. Methods and Results:, During studies on the intestinal microflora of pigs, we isolated E. coli Nissle 1917 sporadically from a pig population over a period of 1 year. The identity of the isolates as E. coli Nissle 1917 was verified by serotyping, Nissle-specific PCR, macrorestriction analysis (pulsed field gel electrophoresis) and the determination of in vitro probiotic properties in invasion and adhesion assays using a porcine intestinal epithelial cell line. Both the E. coli isolates and the E. coli Nissle 1917 strain showed strong reductions in adhesion of porcine enteropathogenic E. coli and invasion of Salmonella typhimurium with epithelial cells in vitro, with a probiotic effect. Screening of five epidemiologically unlinked swine farms and two wild boar groups showed one farm positive for E. coli Nissle 1917. A feeding experiment with four piglets showed viable E. coli Nissle 1917 in the intestine of three animals. Conclusions:, The results of this study suggest that the E. coli Nissle 1917 strain is already partially established in swine herds, but the colonization of individual animals is variable. Significance and Impact of the Study:, We report natural, long-term colonization and transmission of the probiotic E. coli Nissle 1917 strain in a swine herd, characterized individual persistence and colonization properties in swine and established an in vitro porcine intestinal epithelial cell model of probiotic action. The results of this study would have implications in the use of this strain as a probiotic in swine and contribute to a better understanding of the individual nature of intestinal bacterial persistence and establishment. [source] Prevalence of enterohaemorrhagic Escherichia coli from serotype O157 and other attaching and effacing Escherichia coli on bovine carcasses in AlgeriaJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2006A. Chahed Abstract Aims:, Bovine meat is the principal source of human contamination of attaching and effacing Escherichia coli, including enterohaemorrhagic E. coli O157. The aim was to study the prevalence of these strains on bovine carcasses in Algeria. Methods and Results:, Two-hundred and thirty carcasses were swabbed and analysed by classical microbiological methods for total E. coli counts and for the presence of pathogenic E. coli. The E. coli counts were high, with a 75th percentile of 444·75 CFUs cm,2. For pathogenic E. coli, more than 7% of the tested carcasses were positive for E. coli O157. Eighteen E. coli O157 strains were isolated and typed by multiplex PCR. The main isolated pathotype (78%) was eae+ stx2+ ehxA+. In addition to E. coli O157, other attaching and effacing E. coli (AEEC) were also detected from carcasses by colony hybridization after pre-enrichment and plating on sorbitol MacConkey agar using eae, stx1 and stx2 probes. Thirty carcasses (13%) on the 230 analysed harboured at least one colony positive for one of the tested probes. These positive carcasses were different from those positive for E. coli O157. Sixty-six colonies (2·9%) positive by colony hybridization were isolated. The majority (60·6%) of the positive strains harboured an enteropathogenic E. coli -like pathotype (eae+ stx,). Only three enterohaemorrhagic E. coli (EHEC)-like (eae+ stx1+) colonies were isolated from the same carcass. These strains did not belong to classical EHEC serotypes. Conclusions:, In this study, the global hygiene of the slaughterhouse was low, as indicated by the high level of E. coli count. The prevalence of both E. coli O157 and other AEEC was also high, representing a real hazard for consumers. Significance and Impact of the Study:, This is the first study of this type in Algeria, which indicates that the general hygiene of the slaughterhouse must be improved. [source] Use of repetitive DNA sequences to determine the persistence of enteropathogenic Escherichia coli in vegetables and in soil grown in fields treated with contaminated irrigation waterLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2006K. Ibenyassine Abstract Aims:, Fresh fruits and vegetables are increasingly recognized as vectors for food-borne illness. On farm contamination through contaminated irrigation water is considered likely source of the pathogen for several outbreaks. The purpose of this study is to investigate the possible similarity of strains of Escherichia coli isolated from the soil and vegetables irrigated by treated wastewater. Methods and Results:, Seventy-five strains of enteropathogenic Escherichia coli isolated from vegetables, soil and irrigation water were tested for sensitivity to antibiotics and shown to be sensitive. The result of enterobacterial repetitive intergenic consensus (ERIC)-PCR shows similarities between analysed strains isolated from the three different samples. Moreover strains of E. coli isolated from vegetables over different periods of time have the same ERIC-PCR profile. Conclusions:, The isolated strains of enteropathogenic E. coli can persist in soil and in vegetables growing in fields treated with contaminated irrigation water for an extended period of time. Significance and Impact of the Study:, Contaminated irrigation water can transport pathogenic bacteria, which persists in the soil for a long period of time and contaminates the vegetables growing in the field irrigated by this contaminated water. [source] Identification and characterization of NleA, a non-LEE-encoded type III translocated virulence factor of enterohaemorrhagic Escherichia coli O157:H7MOLECULAR MICROBIOLOGY, Issue 5 2004Samantha Gruenheid Summary Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 uses a specialized protein translocation apparatus, the type III secretion system (TTSS), to deliver bacterial effector proteins into host cells. These effectors interfere with host cytoskeletal pathways and signalling cascades to facilitate bacterial survival and replication and promote disease. The genes encoding the TTSS and all known type III secreted effectors in EHEC are localized in a single pathogenicity island on the bacterial chromosome known as the locus for enterocyte effacement (LEE). In this study, we performed a proteomic analysis of proteins secreted by the LEE-encoded TTSS of EHEC. In addition to known LEE-encoded type III secreted proteins, such as EspA, EspB and Tir, a novel protein, NleA (non- LEE-encoded effector A), was identified. NleA is encoded in a prophage-associated pathogenicity island within the EHEC genome, distinct from the LEE. The LEE-encoded TTSS directs translocation of NleA into host cells, where it localizes to the Golgi apparatus. In a panel of strains examined by Southern blot and database analyses, nleA was found to be present in all other LEE-containing pathogens examined, including enteropathogenic E. coli and Citrobacter rodentium, and was absent from non-pathogenic strains of E. coli and non-LEE-containing pathogens. NleA was determined to play a key role in virulence of C. rodentium in a mouse infection model. [source] Enterohaemorrhagic and enteropathogenic Escherichia coli use a different Tir-based mechanism for pedestal formationMOLECULAR MICROBIOLOGY, Issue 6 2001Rebekah DeVinney Enterohaemorrhagic Escherichia coli (EHEC) adheres to the host intestinal epithelium, resulting in the formation of actin pedestals beneath adhering bacteria. EHEC and a related pathogen, enteropathogenic E. coli (EPEC), insert a bacterial receptor, Tir, into the host plasma membrane, which is required for pedestal formation. An important difference between EPEC and EHEC Tir is that EPEC but not EHEC Tir is tyrosine phosphorylated once delivered into the host. In this study, we assessed the role of Tir tyrosine phosphorylation in pedestal formation by EPEC and EHEC. In EPEC, pedestal formation is absolutely dependent on Tir tyrosine phosphorylation and is not complemented by EHEC Tir. The protein sequence surrounding EPEC Tir tyrosine 474 is critical for Tir tyrosine phosphorylation and pedestal formation by EPEC. In contrast, Tir tyrosine phosphorylation is not required for pedestal formation by EHEC. EHEC forms pedestals with both wild-type EPEC Tir and the non-tyrosine-phosphorylatable EPEC Tir Y474F. Pedestal formation by EHEC requires the type III delivery of additional EHEC factors into the host cell. These findings highlight differences in the mechanisms of pedestal formation by these closely related pathogens and indicate that EPEC and EHEC modulate different signalling pathways to affect the host actin cytoskeleton. [source] Virulence genes, serobiotypes and antibiotic resistance profile of Escherichia coli strains isolated from aquaculture and other sourcesAQUACULTURE RESEARCH, Issue 7 2010Surendraraj Alagarsamy Abstract In order to determine the prevalence of pathogenic Escherichia coli, a total number of 155 E. coli isolates from aquaculture, clinical and veterinary sources were screened for seven pathogenic virulence markers and a house-keeping gene by a polymerase chain reaction. The targeted virulence genes included eaeA of enteropathogenic E. coli, elt and est of enterotoxigenic E. coli (ETEC), ipaH of enteroinvasive E. coli, pCVD432 of enteroaggregative E. coli, stx, hlyA and eaeA of shigatoxigenic E. coli (STEC) and Enterohaemorrhagic E. coli. All the isolates were positive for phoA, the house-keeping gene for E. coli. Among the 155 isolates, seven numbers (4.5%) harboured the virulence markers belonging to the pathogenic group ETEC and STEC. The virulent genes detected in these groups were elt, est, hlyA and stx. The sources of these virulence genes were fish (hlyA), shrimp (elt), feeder canal water (hlyA and elt) of aquaculture origin and from diarrhoea affected cow (hlyA, est and stx). The isolates with pathogenic traits belonged to the serogroups O6 or O29 and the remaining could not be typed. They showed resistance to two to four antibiotics out of the 12 antibiotics tested. Biotyping revealed that three isolates belonged to a single biotype (7333) and the remaining isolates were of diverse types. In conclusion, a molecular tool such as PCR proves as more effective tool for detection of this pathogen than the conventional methods. Detection of these emerging pathogens in aquaculture samples warrants for strict adherence to hygienic handling at retail outlets and proper cooking by the consumer before consumption. [source] Enterohaemorrhagic Escherichia coli Tir requires a C-terminal 12-residue peptide to initiate EspFU -mediated actin assembly and harbours N-terminal sequences that influence pedestal lengthCELLULAR MICROBIOLOGY, Issue 9 2006Kenneth G. Campellone Summary Enterohaemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) both utilize type III secretion systems that translocate the effector protein Tir into the plasma membrane of mammalian cells in order to stimulate localized actin assembly into ,pedestals'. The Tir molecule that EPEC delivers is phosphorylated within its C-terminus on tyrosine-474, and a clustered 12-residue phosphopeptide encompassing this residue initiates an efficient signalling cascade that triggers actin polymerization. In addition to Y474, tyrosine-454 of EPEC Tir is phosphorylated, although inefficiently, and promotes actin polymerization at low levels. In contrast to EPEC Tir, EHEC Tir lacks Y474 and triggers pedestal formation in a phosphotyrosine-independent manner by interacting with an additional effector protein, EspFU. To identify EHEC Tir sequences that regulate localized actin assembly, we circumvented the strict requirements for type III translocation and directly expressed Tir derivatives in mammalian cells by transfection. Infection of Tir-expressing cells with a Tir-deficient EHEC strain demonstrated that ectopically expressed Tir localizes to the plasma membrane, is modified by mammalian serine-threonine kinases and is fully functional for actin pedestal formation. Removal of portions of the cytoplasmic N-terminus of Tir resulted in the generation of abnormally long pedestals, indicating that this region of EHEC Tir influences pedestal length. In the presence of the entire N-terminal domain, a 12-residue peptide from the C-terminus of EHEC Tir is both necessary and sufficient to recruit EspFU and initiate actin pedestal formation. This peptide encompasses the portion of EHEC Tir analogous to the EPEC Tir-Y454 region and is present within the Tir molecules of all pedestal-forming bacteria, suggesting that this sequence harbours a conserved signalling function. [source] Attaching and effacing pathogen-induced tight junction disruption in vivoCELLULAR MICROBIOLOGY, Issue 4 2006Julian A. Guttman Summary Diarrhoea is a hallmark of infections by the human attaching and effacing (A/E) pathogens, enterohaemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC). Although the mechanisms underlying diarrhoea induced by these pathogens remain unknown, cell culture results have suggested that these pathogens may target tight junctions. Tight junctions in the colon function as physical intercellular barriers that separate and prevent mixing of the luminal contents with adlumenal regions of the epithelium. Consequently, it is thought that the disruption of intestinal epithelial tight junctions by A/E pathogens could result in a loss of barrier function in the alimentary tract; however, this remains unexamined. Here we demonstrate for the first time that A/E pathogen infection results in the morphological alteration of tight junctions during natural disease. Tight junction alteration, characterized by relocalization of the transmembrane tight junction proteins claudin 1, 3 and 5, is a functional disruption; molecular tracers, which do not normally penetrate uninfected epithelia, pass across pathogen-infected epithelia. Functional junction disruption occurs with a concomitant increase in colon luminal water content. The effects on tissue are dependent upon the bacterial type III effector EspF (E. coli secreted protein F), because bacteria lacking EspF, while able to colonize, are defective for junction disruption and result in decreased proportions of water in the colon compared with wild-type infection. These results suggest that the diarrhoea induced by A/E pathogens occurs as part of functional tight junction disruption. [source] Emergence of a ,hyperinfectious' bacterial state after passage of Citrobacter rodentium through the host gastrointestinal tractCELLULAR MICROBIOLOGY, Issue 8 2005Siouxsie Wiles Summary Citrobacter rodentium belongs to a family of human and animal enteric pathogens that includes the clinically significant enterohaemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC). These pathogens exploit attaching and effacing (A/E) lesions to colonize the host gastrointestinal tract. However, both EHEC and EPEC are poorly pathogenic in mice. In contrast, C. rodentium, which is genetically highly related to E. coli, relies on A/E lesion formation as an essential step in both colonization and infection of the murine mucosa, providing an excellent in vivo model. In this study we have used bioluminescence imaging (BLI) to investigate the organ specificity and dynamics of colonization of mice by LB-grown and mouse-passaged C. rodentium in situ and in real time. We have demonstrated the appearance of a ,hyperinfectious' state after passage of C. rodentium through the murine gastrointestinal tract. The ,hyperinfectious' state was found to dramatically reduce the dose required to infect secondary individuals, and also influenced the tissue distribution of colonizing bacteria, removing the requirement for primary colonization of the caecal patch. In addition, the ,hyperinfectious' phenotype was found to be transient with one overnight passage in rich medium sufficient to return C. rodentium to ,culture' infectivity. [source] A method for fast and simple detection of major diarrhoeagenic Escherichia coli in the routine diagnostic laboratoryCLINICAL MICROBIOLOGY AND INFECTION, Issue 5 2007S. Persson Abstract A multiplex PCR was developed for the detection of the following genes characteristic of diarrhoeagenic Escherichia coli (DEC): verocytotoxins 1 (vtx1) and 2 (vtx2), characteristic of verocytotoxin-producing E. coli (VTEC); intimin (eae), found in enteropathogenic E. coli (EPEC), attaching and effacing E. coli and VTEC; heat-stable enterotoxin (estA) and heat-labile enterotoxin (eltA), characteristic of enterotoxigenic E. coli (ETEC); and invasive plasmid antigen (ipaH), characteristic of enteroinvasive E. coli (EIEC) and Shigella spp. The method allowed the simultaneous identification of all six genes in one reaction, and included a 16S rDNA internal PCR control. When applied to pure cultures from a reference strain collection, all virulence genes in 124 different DEC strains and 15 Shigella spp. were identified correctly, and there were no cross-reactions with 13 non- E. coli species. The detection limit of the method was 102,103 DEC CFU/PCR in the presence of 106 non-target cells. When the multiplex PCR was tested with colonies from plate cultures of clinical stool samples, it was a faster, more sensitive, less expensive and less laborious diagnostic procedure than DNA hybridisation. When used with DNA purified from spiked stool samples (by two different commercial kits), the method had a detection limit of 106 CFU/mL stool sample. [source] | ||||||||||