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

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.

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.

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.

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.