Search

Shiga toxin (Stx)-producing Escherichia coli (STEC) belonging to the "top 7″ serotypes (i.e. O157:H7, O26:H11, O45:H2, O103:H2, O111:H8, O121:H19 and O145:H28) are considered as the main pathogenic enterohemorrhagic E. coli (EHEC). As ruminants, including calves, are a reservoir of pathogenic STEC, we investigated the prevalence, major virulence genes and genetic relatedness of top7 STEC in veal calves slaughtered in France, through the analysis of 500 fecal samples collected over one year. Thirty top7 STEC isolates were recovered from 28 calves. The two serotypes O103:H2 and O26:H11 accounted for 73% of STEC strains, followed by O145:H28 and O157:H7. STEC super-shedding levels were identified for two calves carrying STEC O103:H2 and O157:H7, respectively. Thirty-nine atypical enteropathogenic E. coli (aEPEC) were also recovered from calves. Overall, a prevalence of 5.6% top7 STEC-positive calves was found, thus higher than that previously determined for the French slaughtered adult cattle (1.8%), confirming the impact of animals age on STEC carriage. Most top7 STEC strains carried the stx1a subtype suggesting a low pathogenicity for humans. Seasonal variation in STEC carriage was also observed, with two peaks of higher prevalence during spring and fall. Genetic similarity of top7 STEC isolates was found for calves originating from the same fattening facilities, reflecting STEC circulation between animals kept in groups. This study indicates that veal calves grown for meat production are at higher risk of shedding top7 STEC compared to adult cattle. They thus represent ideal targets for the implementation of farm interventions aimed at reducing STEC burden in cattle and the food chain., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Metallo-β-lactamases (MBLs), porin OprD, integrons, virulence factors and the clonal relationships were characterized in imipenem-resistant Pseudomonas aeruginosa (IRPA) isolates. Fifty-six IRPA strains were recovered from blood samples of different patients at a Toulouse teaching hospital from 2011 to 2013. Susceptibility testing of 14 antibiotics was performed by the disc diffusion method. Detection and characterization of MBLs, the oprD gene and integrons were studied by PCR and sequencing. Thirteen genes involved in the virulence of P. aeruginosa were analysed. Molecular typing of IRPA strains was performed by PFGE and multilocus sequence typing. In this study, 61 % of the IRPA isolates showed a multi-resistance phenotype. The MBL phenotype, detected in three isolates (5.4 %), was linked to the blaVIM-2 gene. The oprD gene was amplified in 55 (98.2 %) IRPA strains, and variations were observed in 54 of them. Insertion sequences (IS) truncating oprD were detected in eight IRPA strains, with the novel ISPa56 identified in two strains. Class 1 integrons were detected in 24 (42.9 %) IRPA strains. The blaVIM-2 gene was found inside the class 1 integron arrangements. The new integrons In1054 (intI1-aacA56-qacEΔ1-sul1) and In1160 (intI1-aacA4-aacC1d-ISKpn4-gcuE-qacEΔ1-sul1) have been described for the first time, to the best of our knowledge, in this study. A high clonal diversity was found in our strains. Among the variety of sequence types (STs) found, ST175, ST233, ST235, ST244 and ST654 were noteworthy as epidemic clones. In conclusion, 5.4 % of IRPA strains showed an MBL phenotype linked to the blaVIM-2 gene. The identified oprD high polymorphism could be implicated in the variable resistance to carbapenems in IRPA strains. The dissemination of high-risk clones is a cause of concern.

The goal of this study was to investigate the involvement of bovine slaughterhouse effluents and biosolids in the risk of environmental dissemination of pathogenic and antibiotic-resistant Escherichia coli. Several samples were collected from one adult cattle and one veal calf slaughterhouse wastewater treatment plant (WWTP). The treatment process had no impact on the percentage of Shiga toxin-producing E. coli (STEC) and on the percentage of atypical enteropathogenic E. coli (aEPEC). A STEC O157:H7 was isolated from the thickened sludge of the adult cattle slaughterhouse. As thickened sludge is intended to be spread on agricultural lands, the detection of this pathogenic strain is a public health issue. The percentage of antibiotic-resistant E. coli was 5.0% and 87.5% in wastewater from the adult cattle and the veal calf slaughterhouse, respectively. These percentages were not significantly different after treatment. Integron-bearing E. coli isolates were only detected in the veal calf slaughterhouse WWTP with percentages above 50.0% for all sampling points whatever the step of the treatment process. Taken together, these findings highlighted the fact that different public health risks might be associated with adult cattle or veal calf slaughterhouses regarding the dissemination of pathogenic and antibiotic-resistant E. coli isolates into the environment., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The main pathogenic enterohemorrhagic Escherichia coli (EHEC) strains are defined as Shiga toxin (Stx)-producing E. coli (STEC) belonging to one of the following serotypes: O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28. Each of these five serotypes is known to be associated with a specific subtype of the intimin-encoding gene (eae). The objective of this study was to evaluate the prevalence of bovine carriers of these “top five” STEC in the four adult cattle categories slaughtered in France. Fecal samples were collected from 1,318 cattle, including 291 young dairy bulls, 296 young beef bulls, 337 dairy cows, and 394 beef cows. A total of 96 E. coli isolates, including 33 top five STEC and 63 atypical enteropathogenic E. coli (aEPEC) isolates, with the same genetic characteristics as the top five STEC strains except that they lacked an stx gene, were recovered from these samples.O157:H7 was the most frequently isolated STEC serotype. The prevalence of top five STEC (all serotypes included) was 4.5% in young dairy bulls, 2.4% in young beef bulls, 1.8% in dairy cows, and 1.0% in beef cows. It was significantly higher in young dairy bulls (P<0.05) than in the other 3 categories. The basis for these differences between categories remains to be elucidated. Moreover,simultaneous carriage of STEC O26:H11 and STEC O103:H2 was detected in one young dairy bull. Lastly, the prevalence of bovine carriers of the top five STEC, evaluated through a weighted arithmetic mean of the prevalence by categories, was estimated to 1.8% in slaughtered adult cattle in France.

We compared the prevalence of pathogenic and extended-spectrum beta-lactamase (ESBL) - producing Escherichia coli in effluents of a municipal wastewater treatment plant (WWTP) receiving wastewater from a slaughterhouse. A total of 1248 isolates were screened for the presence of virulence genes associated with enterohemorrhagic E. coli (EHEC) (stx1, stx2, and eae) and extraintestinal pathogenic E. coli (ExPEC) (sfa/focDE, kpsMT K1, hlyA, papEF, afa/draBC, clbN, f17A and cnf). The prevalence of atypical enteropathogenic E. coli (EPEC) was 0.7%, 0.2% and 0.5% in city wastewater, slaughterhouse wastewater and in the treated effluent, respectively. One stx1a and stx2b-positive E. coli isolate was detected in city wastewater. The prevalence of ExPEC was significantly higher in city wastewater (8.4%), compared to slaughterhouse wastewater (1.2%). Treatment in the WWTP did not significantly impact the prevalence of ExPEC in the outlet effluent (5.0%) compared to city wastewater. Moreover, the most potentially pathogenic ExPEC were isolated from city wastewater and from the treated effluent. ESBL-producing E. coli was also mainly detected in city wastewater (1.7%), compared to slaughterhouse wastewater (0.2%), and treated effluent (0.2%). One ESBL-producing E. coli, isolated from city wastewater, was eae-β1 positive. These results showed that pathogenic and/or ESBL-producing E. coli were mainly detected in human wastewater, and at a lesser extend in animal wastewater. Treatment failed to eliminate these strains which were discharged into the river, and then these strains could be transmitted to animals and humans via the environment., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

In order to improve the identification of avian pathogenic Escherichia coli (APEC) strains, an extensive characterization of 1,491 E. coli isolates was conducted, based on serotyping, virulence genotyping, and experimental pathogenicity for chickens. The isolates originated from lesions of avian colibacillosis (n = 1,307) or from the intestines of healthy animals (n = 184) from France, Spain, and Belgium. A subset (460 isolates) of this collection was defined according to their virulence for chicks. Six serogroups (O1, O2, O5, O8, O18, and O78) accounted for 56.5% of the APEC isolates and 22.5% of the nonpathogenic isolates. Thirteen virulence genes were more frequently present in APEC isolates than in nonpathogenic isolates but, individually, none of them could allow the identification of an isolate as an APEC strain. In order to take into account the diversity of APEC strains, a statistical analysis based on a tree-modeling method was therefore conducted on the sample of 460 pathogenic and nonpathogenic isolates. This resulted in the identification of four different associations of virulence genes that enables the identification of 70.2% of the pathogenic strains. Pathogenic strains were identified with an error margin of 4.3%. The reliability of the link between these four virulence patterns and pathogenicity for chickens was validated on a sample of 395 E. coli isolates from the collection. The genotyping method described here allowed the identification of more APEC isolates with greater reliability than the classical serotyping methods currently used in veterinary laboratories.

Wastewater samples from 12 slaughterhouses located in different regions in France were tested for the presence of stx-positive and eae-positive Escherichia coli isolates, and characteristics of the isolates obtained were determined. A total of 224 wastewater samples were collected in wastewater treatment plants at different stages of wastewater processing. Altogether, 5,001 E. coli isolates were obtained by colony counting and screened for the presence of stx and eae genes by multiplex PCR. stx-positive and eae-positive E. coli isolates were detected in 25% of the samples collected; they were found in 13% and 3% of the samples obtained from treated effluent and sludge, respectively, suggesting that they could be spread into the environment. Screening of the samples collected by immunomagnetic separation allowed us to isolate 31 additional E. coli serogroup O157 isolates. Four of these isolates harbored stx and eae genes. All stx-positive and eae-positive E. coli isolates were analyzed for eae and stx genetic variants, as well as for additional virulence factors and serotypes. Our results suggest that the majority of the stx- and eae-positive E. coli isolates from wastewater have low virulence for humans. However, the diversity of the enterohemorrhagic E. coli-associated virulence factors in the strains indicates that the environment may play an important role in the emergence of new pathogenic enterohemorrhagic E. coli strains.

A collection of 1601 extraintestinal and intestinal Escherichia coli isolated from chickens, turkeys and ducks, in Belgium, France and Spain, was hybridised with gene probes specific for fimbrial and afimbrial adhesins (F17, F18, S , Bfp, Afa, Cs31A, Intimin , Aida-1) of intestinal, urinary and invasive E. coli of mammals and with a probe specific for the P (Pap/Prs) fimbrial adhesin of urinary and invasive E. coli of mammals and birds. Three hundred and eighty-three strains (23.9%) were P-positive, 76 strains (4.8%) were Afa-positive, 75 strains (4.7%) were F17-positive, 67 strains (4.2%) were S-positive, 23 (1.4%) were Intimin-positive, and all were F18-, Cs31A-, Aida1- and Bfp-negative. The 75 F17-positive strains harboured different major subunit A-encoding gene variants, but the f17Ac variant was the most frequent (52 strains, 69.3%) and seven strains (9.3%) were not typeable. The f17G gene variant coding for the GII adhesin was the most frequent (56 strains, 75.0%), whereas the f17GI gene variant was present in four strains (5%) and 15 strains (20.0%) were not typeable. All Afa-positive strains harboured the afa-8 variant. The 23 Intimin-positive E. coli tested positive for the beta-variant (16 strains; 69.6%) or for the gamma-variant (seven strains; 30.4%) of the eae gene. Chicken and turkey E. coli were more frequently probe-positive (43.6 and 43.1%, respectively) than duck E. coli (31.5%) and extraintestinal E. coli were also more frequently probe-positive (48.4%) than intestinal strains (18.5%). Different combinations of probe positive hybridisation results were observed in 72 of the 540 probe-positive E. coli (13.3%). The most frequent combinations were between AfaE-8 and F17 probes (47 strains; 8.7%) and between P and S probes (13 strains; 2.4%). Although f17- and afa-8-related DNA sequences can be plasmid-located in mammalian E. coli, they were not in avian E. coli. Besides the P fimbrial adhesins, F17 and S fimbrial and Afa-VIII and Intimin afimbrial adhesins may thus represent colonisation factors of avian pathogenic E. coli.