Isolation and characterization of antimicrobial resistant Staphylococcus aureus in retail ground meats
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Staphylococcus aureus is commonly present in humans and animals. It can cause a variety of suppurative infections, food intoxication and toxic shock syndrome. Antimicrobial resistant S. aureus, especially methicillin-resistant S. aureus (MRSA), have emerged and are a major public health concern. There is an increasing risk of food production animals serving as a reservoir and transmitting S. aureus and MRSA in community environments. Due to the increased food safety risk posed by MRSA in addition to its multidrug resistance, we were interested in determining the prevalence of S. aureus and MRSA in retail meat and investing the multidrug resistance of the S. aureus isolates. A survey study was conducted, involving 480 retail ground meat samples (231 ground pork and 249 ground beef) collected in the Washington DC area from March 2009 to March 2010. Approximately 42.08% (n = 202) of the samples were identified as S. aureus positive and one MRSA isolate was recovered from a ground beef sample. Antimicrobial resistance testing showed 53.34% of recovered S. aureus isolates exhibited different levels of antimicrobial resistance to CLI, CHL, GEN, LEVO, CIP, SYN and TGC. The MRSA isolate was resistant to 8 of 22 antimicrobials tested. PFGE fingerprinting identified the MRSA isolate as USA300 subtype, which also carried genes of virulence factors PVL and protein A. Our findings indicated that antimicrobial resistant S. aureus strains were common in retail ground beef and port, and that MRSA could also be present in such products that could potentially serve as a reservoir.