ACTA VETERINARIA ET ZOOTECHNICA SINICA ›› 2014, Vol. 45 ›› Issue (5): 853-858.doi: 2013-11-11

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Antimicrobial Susceptibility,Virulence Factors and Molecular Typing of Methicillin-resistant Staphylococcus aureus ST9 from Dairy Cow and Swine

ZHANG Qiang1, XING Xiao-nan1, WANG Xin1*, WANG Xiao2, YU Ying2, WU Cong-ming3, SHEN Jian-zhong3   

  1. (1.College of Food Science and Engineering, Northwest A & F University, Yangling 712100, China;2.College of Animal Science and Technology, China Agricultural University, Beijing 100193, China;3.Department of Pharmacology & Toxicology, College of Veterinary Medicine,
    China Agricultural University, Beijing 100193, China)
  • Received:2013-11-11 Online:2014-05-23 Published:2014-05-23

Abstract:

The aim of this study was to investigate antimicrobial resistance and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) ST 9 from dairy herds and swine.MRSA ST9 isolates were characterized by antimicrobial susceptibility test,pulsed-field gel electrophoresis (PFGE),spa typing,and SCCmec typing,and were examined by PCR for genes encoding enterotoxins,exfoliative toxins,Panton-Valentine leukocidin (PVL),and toxic shock syndrome toxin 1 (Tsst-1).All MRSA ST9 isolates were sensitive to vancomycin.But they showed resistance against other 31 antibiotics to various degrees ranging from 5.6% to 100%.In addition,100% of isolates were positive for one or more toxin genes tested.The four most predominant toxin genes were seg (94.4%),seb (83.3%),sed (72.2%) and PVL (55.6%),followed by sei (11.1%) and,sea (5.6%).ETs,Tsst-1, sec,see,seh and sej genes were not detected.MRSA ST9 isolates belonged to ST9-SCCmec IVb-t899 (94.4%) and ST9-SCCmec II-t899 (5.6%).PFGE suggested potential transmission of MRSA ST9 strains in different farms.Many MRSA ST9-SCCmec IVb-t899 isolates harbored multiple toxin genes and exhibited multiple antimicrobial resistance.The presence of MRSA ST9 strains in these animals poses a potential threat to animal and human health.

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