Molecular characterisation and typing the methicillin resistance of Staphylococcus spp. isolated from raw milk and cheeses in northwest Spain: A mini survey

Abstract During the last decade, the occurrence of methicillin-resistant staphylococci in animals and foods derived from them has been increasingly reported, but the dairy sector still requires further surveillance. For this, 150 samples of raw bovine milk, ovine and caprine chesses were analysed for identification of Staphylococcus spp. isolates based on 16S rRNA gene sequencing and additionally, typing of methicillin resistance (MR) via PCR-targeting of mec -region genes. Accordingly, 84 staphylococci isolates were identified and their 16S rRNA gene sequences were deposited in GenBank. Among these, 2 isolates of each of Staphylococcus chromogenes and Staphylococcus epidermidis were methicillin-resistant. Phenotypically, a variable multidrug-resistance was noticed for the mecA -positive isolates against eleven selected antibiotics. Results demonstrated that coagulase-negative staphylococci can be a carrier for MR, as Staphylococcus aureus does, and could exist in raw milk from lactating animals; which represents a source for MR transmission to the surrounding environment.