Characterization of Shiga Toxin Gene ( stx )-Positive and Intimin Gene ( eae )-Positive Escherichia coli Isolates from Wastewater of Slaughterhouses in France

Abstract

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.

Prevalence of pathogenic and antibiotics resistant Escherichia coli from effluents of a slaughterhouse and a municipal wastewater treatment plant in Dakar

“…In contrast, the E. coli strains were absent after treatment of effluent at the WWTP. These results are opposed to those obtained in several studies conducted in France and elsewhere (Vernozy-Rozand et al, 2002;Loukiadis et al, 2006). This difference could be justified by the various methods of wastewater treatment used in a wastewater treatment plant and the final destination of the treated water.…”

“…Other studies showed the presence of eae-positive E. coli isolates in effluents from human and animal origin (Holler et al, 1999;Vernozy-Rozand et al, 2004;Garcia-Aljaro, 2005;Awais et al, 2007;Ayaz et al, 2014). Loukiadis et al (2006) detected 54 eaepositive E. coli isolates among 5,001 isolates from various effluents from 12 slaughterhouses in France. Here, it was confirmed that the prevalence of eae-positive E. coli isolates in effluents was very low.…”

Evaluation of Major Types of Shiga Toxin 2e-Producing Escherichia coli Bacteria Present in Food, Pigs, and the Environment as Potential Pathogens for Humans

“…Stx2e-producing strains also frequently occur in pigs (16), in the environment of pig farms (46), and as contaminants of wastewater from abattoirs (26). The low incidence of Stx2e strains in human patients could indicate that most of these strains cannot colonize or may infect but do not cause disease in humans.…”

Distribution, Functional Expression, and Genetic Organization of Cif, a Phage-Encoded Type III-Secreted Effector from Enteropathogenic and EnterohemorrhagicEscherichia coli

“…As populations of E. coli from environmental and animal origins may be important natural reservoirs of phages (at least of Stx-encoding phages) that infect E. coli (14,18,23,24), we next investigated the distribution of cif-encoding prophages in a large collection of E. coli isolates from human, animal, and environmental origins. The Cif-encoding prophages were found ubiquitously in E. coli isolates from different origins, countries, and time periods and were always found associated with the LEE.…”