Suspected MRSP isolates, based on resistance to oxacillin,20 were confirmed to carry the mecA gene by PCR.16 (link) All confirmed isolates were stored at −80°C until further studied. To detect clonal clusters, all MRSP isolates stored in 2010–14 were digested by SmaI macrorestriction (New England BioLabs, USA) and separated by PFGE21 (link) with modifications.15 (link) Isolates that were non-typeable by SmaI were digested using AscI (New England BioLabs, USA). PFGE clusters were illustrated with GelCompar II (v. 6.5; Applied Maths NV, Belgium) by UPGMA-based analysis using the Dice similarity coefficient with an 80% similarity cut-off; optimization and position tolerance were set at 1.2% and 1.3%, respectively. At least one isolate from each PFGE cluster was selected for further characterization by MLST and staphylococcal cassette chromosome mec (SCCmec) typing,22 (link),23 (link) with modifications.16 (link) For some isolates, the MLST sequencing result for the tuf gene was poor with published primers.22 (link) Therefore, the primers were modified as follows: tuf 19F, 5′-GTCCAATGCCACAAACTCG-3′; and tuf 19R, 5′-CCAGCTTCAGCGTAGTCTA-3′. MLST results for isolates were extrapolated to all members of the PFGE cluster. Isolates for which data had previously been published were included in the study.15 (link),16 (link)