Virulence profile of antimicrobial-resistant Escherichia coli circulating in cattle slaughtered in southern Brazil.

This study evaluated the occurrence and antimicrobial resistance profile of generic E. coli from cattle slaughtered in Southern Rio Grande do Sul, Brazil. Isolates presenting phenotypic resistance to antimicrobials were further characterized regarding genetic determinants of resistance and virulence, aiming to identify the antimicrobial resistance and virulence profiles of E. coli circulating in cattle in the region. Samples were collected from cattle carcasses (n = 300) and feces (n = 100) at two slaughterhouses. The E. coli isolates were evaluated for antimicrobial susceptibility. In isolates with phenotypic resistance to at least one antimicrobial, the presence of resistance genes for six antimicrobials classes and genetic virulence markers for Diarrheagenic Escherichia coli (DEC) and the Big Six serogroups (O26, O45, O103, O111, O121, and O145) were evaluated. Isolates were also classified according to the Clermont phylogenetic classification. Generic E. coli was detected in 110 (27.5 %) samples. Fifty-one isolates (14.24 %) showed antimicrobial resistance (AMR), and 10 (2.79 %) were multidrug-resistant (MDR). Regarding virulence, 14 (27.45 %) AMR E. coli were identified as non-O157 STEC, including one (1.96 %) enterohemorrhagic E. coli (EHEC), and two (3.92 %) belonging to the O111 serogroup. Two isolates (3.92 %) were atypical enteropathogenic E. coli (aEPEC). AMR E. coli were mainly grouped in phylogroup B1 (74.5 %). Therefore, cattle in the evaluated region are a reservoir of pathogenic and antimicrobial-resistant E. coli, which can spread in the slaughterhouse environment through feces and hides, posing a direct or indirect risk of meat contamination and threatening food safety.