Bacterial Genomic DNA Extraction and PCR Detection

Genomic DNA from each bacterial isolate was extracted by using a lysostaphin-based extraction protocol with the Genomic Mini Kit (A&A Biotechnology, Gdansk, Poland). Detection of the genes blaZ, mecA and mecC was performed by PCR reaction in a total volume of 15 µL, containing 7.5 µL REDTaq^® ReadyMix™ PCR Reaction Mix (Merck, Darmstadt, Germany) and 1 µL of bacterial genomic DNA, by using specific primers (Table S1) and temperature–time procedures as previously published [12 (link),32 ]. The following controls were included in all amplification reactions: S. aureus ATCC 29213 (blaZ-positive S. aureus), S. aureus ATCC BAA-1707 (mecC-positive S. aureus), S. aureus ATCC 25923 (mecA, blaZ-negative S. aureus), S. epidermidis ATCC 12228 (mecA, mecC-negative S. epidermidis) and negative control (water).