Staphylococcus em queijo Minas Frescal: ocorrência, perfil de susceptibilidade a antimicrobianos e aspectos da virulência

Abstract

In this study, antimicrobial susceptibility patterns, molecular markers of antimicrobial and biocide-resistance occurrence and virulence-associated characteristics were evaluated in CoNS and S. aureus isolated from soft cheese in Brazil. A total of 246 bacterial isolates were recovered from 35 cheese samples belonging to five batches with seven different trademarks. The bacterial counts ranged from 103 to 107 CFU g1. High antimicrobial resistance percentages were observed for oxacillin, penicillin and erythromycin for both S. aureus and SCN. A low antimicrobial resistance percentage was observed for chloramphenicol, and all of the tested bacteria were susceptible to vancomycin and linezolid. In total, a multiple antibiotic resistance (MAR) index of > 0.2 was observed for 80.6 % and 84.2 % of the isolated CoNS and S. aureus, respectively. However, the MAR index ranged from 50 % to 100 % when only bacterial cheese isolates belonging to the same trademark were considered. Regarding to the prevalence of SCN and S. aureus carrying mecA gene, respectively, 81.5 % e 47,4 % of the isolated strains were mecA+, and 76.2 % and 42.1 % of these were phenotypically resistant to oxacillin. Three isolates carried the enterotoxin A gene (sea), 30.5 % produced biofilm in a laboratory test, and α- or ßhemolysis was observed for 2,8 % and 7.2 %, respectively, for all the Staphylococcus spp.. blaZ, mecA, msrA, msrB, linA, aacA-aphD, and smr were most prevalent molecular markers found both in SCN and S. aureus strains. This study highlights the extent of the antimicrobial resistance phenomenon in neglected foodborne microorganisms and the potential public health risks that are related to the consumption of Staphylococci-contaminated soft cheese.