An investigation of staphylococcal chromosomal cassette mec typing of methicillin-resistant Staphylococcus aureus clinical isolates

Objective To investigate the distribution characteristics of staphylococcal chromo- somal cassette mec(SCCmec)typing of methicillin-resistant Staphylococcus aureus(MRSA)clinical isolates in our country.Methods Two hurdred and sixty six strains of S.aureus were collected from 17 hospitals in China.The minimal inhibitory concentrations(MIC)of 23 antimicrobial agents were determined by agar dilution method.SCCmec typing was conducted by multiplex polymerase chain reaction(PCR).Results All isolates showed different resistant phenotypes to various antimicrobial agents.One hurdred and sixty strains(60.2%)were MRSA.SCCmec typing results showed that one strain was SCCmec typeⅡ(0.6%),4 were SCCmec typeⅡsubtype(2.5%),108 were SCCmec typeⅢ(67.5%)with another 342 bp(dcs)amplification bands,20 were SCCmec typeⅢ(12.5%),11 were SCCmec typeⅢA(6.9%),and 16(10%)couldn't be typed,No typeⅠand typeⅣwere detected.Conclusion The major SCCmec type of MRSA in China is SCCmec typeⅢ-dcs,which are multidrug resistant strains,and different from SCCmec typeⅢand SCCmec typeⅢA.