Detection of β-lactamase, blaZ and mecA in penicillin-resistant Staphylococcus aureus isolated from bovine mastitis in Garanhuns, Brazil

Abstract

There are few reports in the literature about genetic determinants of resistance to β-lactams in Staphylococcus aureus isolated from dairy cattle located in the municipality of Garanhuns, state of Pernambuco, Brazil. Thus, this study aimed to investigate the production of β-lactamase and the presence of the blaZ and mecA genes in penicillin-resistant S. aureus isolated from cases of subclinical bovine mastitis in the city of Garanhuns. Forty-six strains of penicillin-resistant S. aureus were evaluated using the nitrocefin disc test and duplex PCR. The results revealed that 45 strains (97.8%) were positive for β-lactamase production and 44 (95.7%) carried the blaZ gene. Among the latter, 43 (97.7%) were β-lactamase producers and only one (2.3%) was not. The mecA gene was not detected in any of the isolates investigated. The results suggest that enzymatic inactivation is the main β-lactam resistance mechanism expressed by S. aureus in the herds analyzed.