Molecular detection of Shiga toxin and extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates from sheep and goats.

Abstract

The Shiga toxin (Stx)-producing Escherichia coli (STEC) have become important global public health concerns. This study investigated the prevalence, antimicrobial resistance profile, and extended-spectrum beta-lactamase-producing E. coli in sheep and goat faeces. A total of 53 E. coli isolates were confirmed by PCR targeting the uidA [β-D glucuronidase] gene. The Shiga toxin genes stx1 and stx2, as well as bfpA, vir, eaeA, lt and aafII virulence genes, were detected in this study. Of the 53 isolates confirmed to be STEC, 100% were positive for stx2 and 47.2% for stx1. Three isolates possessed a combination of stx1 + stx2 + eaeA, while four isolates harboured stx1 + stx2 + vir virulence genes. The isolates displayed phenotypic antimicrobial resistance against erythromycin (66.04%), colistin sulphate (43.4%), chloramphenicol (9.4%) and ciprofloxacin (1.9%). A total of 28.8% of the strains were phenotypically considered ESBL producers and contained the beta-lactamase blaCTX-M-9 and blaCTX-M-25 gene groups. A larger proportion of the E. coli strains (86.8%) contained the antibiotic sulphonamide resistant (sulII) gene, while 62.3%, 62.3%, 52.8%, 43.4%, 41.5%, 20.8%, 18.9%, 11.3%, 11.3%, 9.4%, 9.4% and 5.7% possessed mcr-4, floR, mcr-1, tet(A), sulI, tet(O), tet(W), parC, mcr-2, ampC 5, qnrS and ermB genes, respectively. Thirteen isolates of the ESBL-producing E. coli were considered multi-drug resistant (MDR). One Shiga toxin (stx2) and two beta-lactamase genes (blaCTX-M-9 and blaCTX-M-25 groups) were present in 16 isolates. In conclusion, the E. coli isolates from the small stock in this study contained a large array of high antibiotic resistance and virulence profiles. Our findings highlight the importance of sheep and goats as sources of virulence genes and MDR E. coli. From a public health and veterinary medicine perspective, the characterization of ESBL producers originating from small livestock (sheep and goats) is crucial due to their close contact with humans.