Resistant enterococci isolated from raw sheep’s milk and cheeses from South region of Brazil

Abstract

Enterococci have been used as sentinel organisms for monitoring antimicrobial resistance in food, humans, and other animals. In this sense, the present study evaluated the antimicrobial susceptibility profile and the presence of genes associated with resistance to erythromycin (msrC and ermB) and tetracycline [tet(M) and/or tet(L)] in enterococci isolated from raw sheep’s milk and cheeses (colonial, feta-, and pecorino-type) from South region of Brazil. A total of 156 enterococci were isolated from milk (n=80) and cheese (n=76) samples, identified by MALDI-TOF. Enterococcus faecalis (50.6%; n=79) was the most frequent species isolated from both samples. According to in vitro susceptibility tests, enterococci strains were not susceptible to the most commonly antimicrobial agents used in human and veterinary medicine. The frequency of MDR strains in enterococci isolated from milk (53.7%) was higher than those from cheese (24.2%). The tet(M) gene was the most commonly detected among tetracycline not-susceptible strains. The present study provided the first evidence of antimicrobial not-susceptible enterococci in raw sheep’s milk and cheeses in South Brazil. Drug-resistant strains, particularly those that are MDR, constitute a One Health issue.