Profiles of Non-aureus staphylococci in retail pork and slaughterhouse carcasses: prevalence, antimicrobial resistance, and genetic determinant of fusidic acid resistance

As commensal colonizers in livestock, there has been little attention on staphylococci, especially non-aureus staphylococci (NAS), contaminating meat production chain. To assess prevalence of staphylococci in retail pork and slaughterhouse carcass samples in Korea, we collected 578 samples from Korean slaughterhouses (n = 311) and retail markets (n = 267) for isolation of staphylococci and determined antimicrobial resistance phenotypes in all the isolates. The presence of and prevalence of fusB-family genes (fusB, fusC, fusD, and fusF) and mutations in fusA and fusE genes were examined in fusidic acid resistant isolates. A total of 47 staphylococcal isolates of 4 different species (S. aureus, n = 4; S. hyicus, n = 1; S. epidermidis, n = 10; M. sciuri, n = 32) were isolated. Fusidic acid resistance were confirmed in 9/10 S. epidermidis and all of the 32 Mammaliicoccus sciuri (previously Staphylococcus sciuri) isolates. Acquired fusidic acid resistance genes were detected in all the resistant strains; fusB and fusC in S. epidermidis and fusB/C in M. sciuri. MLST analysis revealed that ST63 (n =10, 31%) and ST30 (n =8, 25%) genotypes were most prevalent among fusidic acid resistant M. sciuri isolates. In conclusion, the high prevalence of fusB family genes in S. epidermidis and M. sciuri strains isolated from pork meat indicated that NAS might act as a reservoir for fusidic acid resistance gene transmissions in pork production chains.