Prevalence and characterization of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus isolated from retail yak butter in Tibet, China

This study aimed to investigate the prevalence, molecular characteristics and antibiotic resistance of Staphylococcus aureus isolates from yak butter in Tibet, China. A total 218 samples were collected retail stores Tibet screened for Staph. aureus. Furthermore, virulence genes, antimicrobial susceptibility, typing [pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, staphylococcal protein (spa) typing] detected. The results showed that 12.4% contaminated with aureus, including 5 positive methicillin-resistant (MRSA). Among all isolates, 96.3% harbored one or more classical (sea sec), novel enterotoxin-encoding genes (seh, sek, sel, seq), hemolysin (hla hld). All resistant at least 2 different classes, most commonly sulfonamides, β-lactams, erythromycin. For blaZ (74.1%) was frequently detected, followed by dfrG (51.9%), erm(B) (22.2%), mecA (18.5%), tet(K) (14.8%), aph(2″)-Ia, aph(3′)-III, ant(6)-Ia (11.1% each), erm(C) (7.4%). We detected 8 spa types, 6 types (ST), clonal complex (CC) types. In addition, 1 isolate nontypeable. found CC1-ST1-t559 (55.6%) predominant clone, CC59-ST59-t437 (11.1%), CC5-ST5-t002 (7.4%), CC1-ST1, CC1-ST1-t114, CC1-ST573-t4938, CC1-ST573-t8915, CC30-ST30-t021, CC25-ST25-t167 (3.7% each). PFGE a clusters 15 pulsotypes generated, some indistinguishable pulsotypes. Our findings suggest produced China, could be strains, MRSA carrying various representing multiple phenotypes. presence potentially virulent antibiotic-resistant strains poses potential threat consumers, appropriate measures need taken production chain reduce occurrence butter.