Impact of polymorphisms in blaZ, blaR1 and blaI genes and their relationship with β-lactam resistance in S. aureus strains isolated from bovine mastitis.

There is not a consensus between the presence of the genotypic resistance marker gene and the phenotypic resistance to β-lactams in Staphylococcus aureus, which means, positive S. aureus blaZ isolates demonstrating sensitivity to β-lactams. The present study aimed to characterize the blaZ, blaR1 and blaI genes, identify and evaluate single nucleotide polymorphisms (SNPs) and their relationship with β-lactam resistance in samples of Staphylococcus aureus obtained from cases of bovine mastitis.