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Occurrence and characterization of stx and/or eae-positive Escherichia coli isolated from wildlife, including a typical EPEC strain from a wild boar.

Research paper by Carla Andrea CA Alonso, Azucena A Mora, Dafne D Díaz, Miguel M Blanco, David D González-Barrio, Francisco F Ruiz-Fons, Carmen C Simón, Jorge J Blanco, Carmen C Torres

Indexed on: 02 Aug '17Published on: 02 Aug '17Published in: Veterinary Microbiology



Abstract

Shiga toxin-producing E. coli (STEC) and enteropathogenic E. coli (EPEC) strains are food-borne pathogens associated with acute diarrhea. Haemolytic-uremic syndrome (HUS) is often a complication of STEC infection. In order to examine the occurrence, serotypes, virulence and antimicrobial-resistance profiles of STEC and EPEC in wildlife, 326 faecal E. coli strains from 304 clinically healthy animals were analyzed. For this approach stx1, stx2 and eae genes, as well as accessory virulence determinants (ehx, hlyA, saa, tia, bfp, subAB) were PCR-screened and sequenced. Serotyping was performed employing all available O (O1-O185) and H (H1-H56) antisera. Genetic diversity was analyzed by XbaI-PFGE and phylotyping. Thirteen STEC (4.3%) and 10 EPEC (3.3%) were identified among 12 deer, 3 mouflon, 6 wild boars and 2 birds. Nine STEC showed seropathotypes B (O145:[H28]) and C (O22:H8, O128:[H2]) associated with HUS, and D (O110:H28, O146:H21, O146:[H28], ONT:H8) associated with human diarrhea. Although most isolates harbored stx2b and stx1c variants, stx2a and stx1a (related with severe disease) were also detected. Additionally, the eae gene was present in one stx2a-positive O145:[H28] STEC from a deer and 11 STEC harbored subAB genes (mainly the subAB2 variant). EPEC isolates showed 7 different intimin variants (β1, β2, γ1, ε1, ζ1, ι1-A, κ). Interestingly, the O49:[H10] eae-κ EPEC isolated from a wild boar was bfpA-positive showing a combination of serotype/virulence profile previously detected among human clinical tEPEC. Based on present results, wild ruminants, wild boars and to a lesser extent birds would be carriers of potentially pathogenic STEC and EPEC strains.

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