Molecular Microbiological Investigation of an Outbreak of Hemolytic-Uremic Syndrome Caused by Dry Fermented Sausage Contaminated with Shiga-Like Toxin-ProducingEscherichia coli (original) (raw)
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Applied and Environmental Microbiology, 1998
In this study we investigated whether the enterohemorrhagic Escherichia coli (EHEC) hemolysin gene ehxA could be used as an indicator of pathogenicity in Shiga-like-toxin-producing Escherichia coli (SLTEC) isolates. The isolates in a collection of 770 SLTEC strains of human and bovine origins were assigned to group 1 (230 human and 138 bovine SLTEC isolates belonging to serotypes frequently implicated in human disease), group 2 (85 human and 183 bovine isolates belonging to serotypes less frequently implicated in disease), and group 3 (134 bovine isolates belonging to serotypes not implicated in disease). PCR amplification was used to examine all of the SLTEC isolates for the presence of ehxA and the virulence-associated genes eae, slt-I, and slt-II. The percentages of human isolates in groups 1 and 2 that were positive for ehxA were 89 and 46%, respectively, and the percentages of bovine isolates in groups 1 to 3 that were positive for ehxA were 89, 51, and 52%, respectively. The percentages of human isolates in groups 1 and 2 that were positive for eae were 92 and 27%, respectively, and the percentages of bovine isolates in groups 1 to 3 that were positive for eae were 78, 15, and 19%, respectively. The frequencies of both ehxA and eae were significantly higher for group 1 isolates than for group 2 isolates. The presence of the ehxA gene was associated with serotype, as was the presence of the eae gene. Some serotypes, such as O117:H4, lacked both eae and ehxA and have been associated with severe disease, but only infrequently. The slt-I genes were more frequent in group 1 isolates than in group 2 isolates, and the slt-II genes were more frequent in group 2 isolates than in group 1 isolates. In a second experiment we determined the occurrence of the ehxA and slt genes in E. coli isolated from bovine feces. Fecal samples from 175 animals were streaked onto washed sheep erythrocyte agar plates. Eight E. coli-like colonies representing all of the morphological types were transferred to MacConkey agar. A total of 1,080 E. coli isolates were examined, and the ehxA gene was detected in 12 independent strains, only 3 of which were positive for slt. We concluded that the ehxA gene was less correlated with virulence than the eae gene was and that EHEC hemolysin alone has limited value for screening bovine feces for pathogenic SLTEC because of presence of the ehxA gene in bovine isolates that are not SLTEC.
Foodborne Pathogens and Disease, 2009
Shiga toxin-producing Escherichia coli (STEC) strains belonging to serogroup O145 are an important cause of hemorrhagic colitis and hemolytic uremic syndrome worldwide. Cattle and other animals are potential reservoirs for this pathogen. To develop PCR assays for detection and identification of E. coli O145, the wzx (O-antigen flippase) and wzy (O-antigen polymerase) genes in the O145 O-antigen gene cluster that are specific for this serogroup were selected as targets. Oligonucleotide primers complementary to regions in the E. coli O145 wzx and wzy genes were designed to perform PCR assays with DNA from strains of E. coli O145, non-O145 E. coli serogroups, and other bacterial genera. The assays were highly specific for E. coli O145. A multiplex PCR assay targeting the E. coli O145 wzx and wzy genes and the Shiga toxin 1 (stx 1 ) and Shiga toxin 2 (stx 2 ) genes and a realtime multiplex PCR assay targeting the O145 wzy, stx 1 , and stx 2 genes were developed for detection of STEC O145. The assays were used for detecting STEC O145 in seeded ground beef, lettuce, and raw milk initially inoculated with ca. 2, 20, or 200 CFU=25 g or 25 mL after 8 or 20 h of enrichment at 428C in modified EC broth containing 20 mg=L of novobiocin. STEC O145 was detected in all samples inoculated with 2 CFU=25 g or 25 mL. The detection limit of the multiplex PCR assays was 7.9Â10 4 CFU=mL, which corresponded to 400 CFU=PCR reaction. The PCR assays can be employed to identify enterohemorrhagic E. coli serogroup O145 and to detect low levels of the pathogen in food.
Journal of Medical Microbiology, 1994
Summary. Shiga-like toxin-producing (SLT) Escherichia coli, particularly those belonging to serogroup 0 157, are responsible for haemorrhagic colitis, haemolytic uraemic syndrome and some cases of gastro-enteritis. The rapid and reliable diagnosis of all these infections is necessary for correct patient management and for epidemiological reasons, but is rarely possible with present methods. We compared the efficacy of two methods, (i) the culture of faeces in broth that contained mitomycin C followed by enzyme-linked immunosorbent assay (ELISA) for SLTs, and (ii) the culture of faeces on sorbitol MacConkey agar (SMA), in the detection of infections caused by SLT-producing E. coli. SLT-producing E. coli 0 157 strains were isolated on SMA from 42 of 475 faecal samples, but SLTs were detected by ELISA in culture supernates or lysates of 54 of 475 samples. SLT-producing E. coli strains were isolated subsequently from 1 1 of 12 ELISA-positive, SMA culture-negative samples by a colony blot technique. In four cases, SLT-producing E. coli of serogroups other than 0 1 5 7 were isolated and in seven cases E. coli 0 1 5 7 was isolated in small numbers. The ELISA is a rapid and sensitive technique for the diagnosis of SLT-producing E. coli infection, especially where low numbers of the organism are present in faeces and when the infection is caused by a serogroup other than 0157. 17 24 1 J M M 40
Journal of Clinical Microbiology, 1993
In this study, the polymerase chain reaction (PCR) was used in the detection of the attaching and effacing (eae) gene of Shiga-like toxin-producing Escherichia coli (SLT-EC). Oligonucleotide primers, complementary to the 5' portion of the eae gene of the enteropathogenic E. coli E2348/69 (0127:H6) and of SLT-EC CL8 and EDL933 (0157:H7), generated PCR products of the predicted sizes with DNA from the majority of human clinical SLT-EC strains tested from 0 serogroups 5, 26, 103, 111, 121, 128, 145, and 157; all SLT-EC strains of 0 serogroups 5, 26, and 111 from cattle; and a minority of porcine SLT-EC strains (one strain each from O serogroups 107 and 130 and one rough strain). Five HaeUI digestion profiles were obtained for PCR products generated by amplification of a 2.3-kb DNA fragment from the 5' end of eae. The HaeHI profiles for SLT-EC O serogroups, such as 26, 103, and 157, differed from each other but were consistent among strains within these O serogroups. Oligonucleotide primer pairs complementary to the 3' end of either the 0127:H6 E. coli or the 0157:H7 eae nucleotide sequence only amplified DNA from E. coli strains from a few of the SLT-EC 0 serogroups examined. One primer pair with homology to the 3' nucleotide sequence of eae from E. coli 0157:H7 appeared to be relatively specific for this 0 serogroup by PCR. No PCR products were obtained in amplification experiments with the eae primers using DNA from human SLT-EC of 0 serogroups 38 (1 of 1) and 91 (3 of 3), 15 of 15 SLT-EC strains from edema disease, or 29 of 29 non-SLT-EC strains from pigs and calves with diarrhea.
Journal of Research in Veterinary Medicine, 2019
This research investigated the presence of virulence genes encoding F41, K99, eae, Stx1, Stx2 and STa and the antimicrobial resistance of animal Escherichia coli (E. coli) isolates. Clinical isolates (n:233) were evaluated from fecal samples of cattle, sheep, goats, horses, cats and dogs collected between the years of 2010 to 2015 from Turkey. Enterohaemorrahic E.coli (EHEC) O157:H7 was detected by using cefixime tellurite sorbitol MacConkey agar (CT-SMAC) and Wellcollex E. coli (Remel®). The Kirby-Bauer disc diffusion test was performed to detect the resistance pattern of the isolates to ampicillin, Amoxycilin/clavulanic acid, enrofloxacin, ceftiofur, trimethoprim/sulfamethoxazole and tetracycline. The results showed that 40% of the ruminant isolates were identified as Shiga-toxin producing Escherichia coli (STEC). Enterotoxigenic E. coli (ETEC) was detected in samples from cattle (0.9%) and sheep (12%). Enteropathogenic E.coli (EPEC) was detected in samples from cattle (0.9%) and dogs (11.4%). EHEC O157:H7 was not detected any of the isolate. Among all E.coli isolates that carried at least one virulence gene, 8 (19%) were resistant to more than three antimicrobials, 7 (16.7%) were resistant to at least one antimicrobial and 27 (64.3%) were susceptible to all antimicrobials.
Journal of Clinical Microbiology, 1993
A single pair of oligonucleotide primers was used for polymerase chain reaction amplification of a 212- or 215-bp region of Escherichia coli Shiga-like toxin (SLT) genes from crude fecal culture extracts. Genes were typed by hybridization of the polymerase chain reaction products to SLT-I- or SLT-II-specific oligonucleotide probes. The procedure was capable of detecting fewer than 10 SLT-producing E. coli organisms per ml of culture against a background of more than 10(9) other organisms per ml and provides a rapid and sensitive means of screening primary fecal cultures for the presence of such strains. When this procedure was used to test primary cultures from gut contents or feces from various patient groups, including apparently healthy infants, approximately half of all samples yielded positive results for SLT-I and/or SLT-II sequences.
Research Square (Research Square), 2023
Background: Enterohemorrhagic Escherichia coli (EHEC) O157 is implicated in serious food and water-borne diseases as hemorrhagic colitis (HC), and the potentially fatal hemolytic uremic syndrome (HUS). However, new players of non-O157 EHEC have been implicated in serious infections worldwide. This work aims at analyzing serotype and genotypic-based virulence pro le of EHEC local isolates. Methods: A total of 335 samples from various clinical and environmental sources in Egypt. E. coli were isolated and subjected to serotyping. Non-O157 EHEC were subjected to PCR to detect virulence genes, phenotypic examination, phylogenetic typing, and molecular investigation by ERIC typing and MLST to disclose genetic relatedness of isolates. A heat map was used to identify potential associations between the origin of the isolates and their phenotypic and genotypic characteristics. Results: A total of 105 out of 335 isolates were identi ed as E. coli. Surprisingly, 49.5% of these isolates were EHEC, where O111, O91, O26 and O55 were the most prevalent serotypes including 38.46% from stool, 21.15% urine, 23.1% cheese, 9.62% meat products, 3.85% from both yogurt and sewage water. Screening 15 different virulence genes revealed that sheA, stx2 and eaeA were the most prevalent with abundance rates of 85%, 75% and 36%, respectively. Fifteen pro les of virulence gene association were identi ed, where the most abundant one was stx2/sheA(19%) followed by stx2/stx2g/sheA/eae (11.5%). Both stx2/sheA/eae and stx2/stx2g/sheA were equally distributed in 9.6% of total isolates. Phylogenetic typing revealed that pathogenic phylogroups B2 and D were detected among clinical isolates only. Forty-six different patterns were detected by ERIC genotyping. MLST resolved three sequence types of ST70, ST120 and ST394. The heat map showed that 21 isolates were of 70% similarity, 9 groups were of 100% clonality. Conclusions: The prevalence of non-O157 EHEC pathotype was marginally higher among the environmental isolates compared to the clinical ones. The endemic ST120 was detected in cheese, necessitating crucial measures to prevent the spread of this clone. Clinical EHEC isolates exhibited a higher score and combination of virulence genes compared to environmental isolates, thereby posing a signi cant public health concern due to limited treatment options.