Risk for public health of multiresistant Shiga toxin-producing Escherichia coli (STEC) in wild boar (Sus scrofa) in Tunisia.

BACKGROUND

Wild boar (Sus scrofa) is increasingly implicated as a reservoir of various pathogens, such as Shiga toxin-producing E. coli (STEC) that are transmissible to other wildlife, domestic animals and humans. This represents risks to both human and animal health by causing food-borne infections. This investigation set out to evaluate the antibiotic resistance profiles and virulence factor rates of STEC strains isolated from wild boars.

MATERIAL AND METHODS

A total of 110 fecal samples were taken from postmortem carcasses of wild boar that were collected during the hunting campaign. PCR was used to check for the presence of the STEC virulence genes stx1, while stx2, eaeA, and ehxA in E. coli isolates. The detection of STEC serogroups was carried out by PCR amplification. Additional virulence genes, phylogenetic groups and integrons were determined in the STEC strains. Antibiotic resistance was assessed in the isolates against 21 antimicrobial agents by disk-diffusion method.

RESULTS

STEC isolates were identified in 10.9 % (12/110) of the E. coli isolates and the serogroups were O157, O145, O45 and O26. Of the strains, 75 % contained the Shiga toxin-1 gene (stx1), stx2 and ehxA were identified in 66.7 % and 33.3 % respectively. Other virulence factors fimH, traT, iutA, cdt3, ibeA, aer and fyuA were found in 100 %, 50 %, 41.7 %, 41.7 %, 33.3 %, 25 % and 8.3 % of the strains, respectively. Integrons classes 1 and 2 were found in 58.3 % and 8.3 % of the strains, respectively. The majority of STEC isolates belonged to phylogroup B1 (58.4 %), followed by E (25 %), A (8.3 %), and D (8.3 %).

CONCLUSIONS

Our findings suggest that wild boars are an important reservoir of STEC isolates. Based on the presence of virulence factors encoding for toxins (stx1 and stx2), adhesins, and invasion among STEC strains in association with integrons as mobile genetic elements, these strains may have a high potential to cause human disease.