Isolation and characterization of methicillin-resistant Staphylococcus aureus from swine and workers in China.

OBJECTIVES: The objectives of this study were to determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization in livestock and related workers in four Chinese provinces and the characteristics of these isolates.

METHODS: Nasal swabs were collected from animals and farm workers in four Chinese provinces. MRSA isolates were recovered and characterized by PFGE, Panton-Valentine leucocidin PCR, staphylococcal chromosomal cassette (SCC) mec typing, spa typing, multilocus sequence typing, antimicrobial susceptibility testing and testing for inducible clindamycin resistance.

RESULTS: A total of 60 MRSA isolates were recovered from swine and swine workers. Two predominant multidrug resistance profiles were identified: ciprofloxacin/clindamycin/erythromycin/cefoxitin/gentamicin/tetracycline/chloramphenicol and ciprofloxacin/clindamycin/erythromycin/cefoxitin/gentamicin/tetracycline. All isolates were determined to be spa type t899, contained the group III SCCmec element and were Panton-Valentine leucocidin negative. Multilocus sequence type ST9 (n = 46) was identified as the dominant sequence type. One dominant PFGE cluster and a dominant strain type were identified.

CONCLUSIONS: MRSA from Chinese pigs and farm workers (ST9) differed from the European pig-associated clone (ST398) with regard to clonal type, SCCmec content and resistance profile.