Prevalence and characteristics of livestock-associated methicillin-susceptible Staphylococcus aureus in the pork production chain in Korea

• Published in: Journal of veterinary science (Suwŏn-si, Korea) Vol. 20; no. 6; p. e69
• Main Authors: Eom, Hong Sik, Back, Seung Hyun, Lee, Haeng Ho, Lee, Gi Yong, Yang, Soo Jin
• Format: Journal Article
• Language: English
• Published: Korea (South) The Korean Society of Veterinary Science 01.11.2019; 대한수의학회
• Subjects: Animal Husbandry; Animals; Methicillin - pharmacology; Methicillin Resistance - genetics; Methicillin-Resistant Staphylococcus aureus - isolation & purification; Original; Prevalence; Republic of Korea - epidemiology; Staphylococcal Infections - epidemiology; Staphylococcal Infections - microbiology; Staphylococcal Infections - veterinary; Swine; Swine Diseases - epidemiology; Swine Diseases - microbiology; 수의학; Republic of Korea; MSSA; zinc resistance; ST398; antimicrobial resistance; pig
• ISSN: 1229-845X; 1976-555X
• DOI: 10.4142/jvs.2019.20.e69

The emergence and prevalence of methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) in livestock animals have become a worldwide public health concern. While the prevalence and genetic profiles of MRSA strains in pigs and pork meat have been actively studied, livestock-associated MSSA strains have only been characterized in a few small-scale studies. In this investigation, we assessed the nationwide prevalence of MSSA in the Korean pig production chain, including pig farms, slaughterhouses, and retail markets. Among the 41 MSSA strains, the predominant clonal lineages were sequence type (ST) 398 (n = 15, 37%) and ST5 (n = 13, 32%). Although the overall prevalence of MSSA (2.58%) was low and mostly restricted to pig farms, ST398 MSSA strains showed higher level of multidrug resistance phenotype versus non-ST398 MSSA strains. In addition to the MDR phenotype, all of the ST398 MSSA strains exhibited resistance to tetracycline as they harbored the (K), (L), and/or (M) genes. However, ST398 MSSA strains did not exhibit increased resistance to zinc compared with the non-ST398 strains. This study is the first to provide evidence of ST398 MSSA emergence in livestock animals in Korea. Further studies are necessary to elucidate the potential of ST398 MSSA strains for human transmission. Our findings suggest that the MDR phenotype and high levels of tetracycline resistance may have played an important role in the emergence and prevalence of ST398 MSSA in pig farms in Korea.