Molecular Characterization, Antibiotic Resistance, and Virulence Factors of Methicillin-ResistantStaphylococcus aureusStrains Isolated from Imported and Domestic Meat in Korea

During a nationwide surveillance in Korea, 13 methicillin-resistant Staphylococcus aureus (MRSA) strains were isolated from imported and domestic meat between 2009 and 2011. The predominant MRSA genotype was SCCmec type V, and only two agr types (I and II) were found. Unexpectedly, sequence type ST72 comprised more than 50% of the isolates; this is the first instance of type ST72 in food from Canada. Two Spanish pork isolates were ST398, which caused human disease in Europe, and they carried leukotoxin genes, lukS, lukF, and lukE-lukD. Furthermore, P71 and P6 harbored all of the known leukocidin genes, lukS-lukF-lukE-lukD-lukM. Our collected MRSA strains were multidrug resistant with various antimicrobial and heavy-metal resistance genes. Toxin genes that are commonly found in clinical MRSA also were detected in our meat strains. One MRSA strain exhibited an uncommon type of enterotoxin, sec-see-seg-sei-sel-sem-sen-seo-sep. Plasmids (1.5-15.0 kb) were found in 12 of the 13 MRSA isolates. Repetitive sequence-based polymerase chain reaction of the genomic DNA showed 3 clusters with 95% similarity. The presence of multidrug-resistant and toxigenic MRSA in meat products suggests that comprehensive surveillance should be continued for imported meats in Korea.