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Objective:96 strains of methicillin-resistant Staphylo-coccus aureus(MRSA)were genotyped by multiplex PCR so as to identify the epidemiological characteristics of MRSA isolated from the hospital.It will be helpful to study on the pathogenesis of MRSA.Materials and Methods:96 strains of MRSA isolated consecutively in first affiliated municipal hospital from July 2006 to December 2007 were studied.They were collected from sputus(74strains),blood(3strains),asictes(Istrain),wounds(15stra ins)and pus(istrain).All of the MRSA strains were identified by using commonly phenotypic procedure and antimicrobial susceptibility tests were performed on all of the strains by K-B method.MICs of oxacillin were determined by agar dilution method. Multiplex PCR was used to genotype Staphylo-coccal chromosomal cassette mec(SCCmec) element and its variants and to reflect the correlation and homology among the isolates using clustering anasysis at the same time.Results:The phenotyping results denoted that all MRSA strains were susceptible to vancomycin and resistant to ciprofloxacin and penicillin.The resistance rate to erythromycin,tetracycline, trimethoprimsulfamethoxazole,clindamycin were 98.9%,98.9%,94.7% and 100%,respectively.These 96 strains could be divided into three types,that is,SCCmec-Ⅲ(91 strains),SCCmec-ⅢA(1 strain), SCCmec-Ⅳ(2 strains),SCCmec-Ⅰ(1 strain)and nontypeable SCCmec type (SCCmec-NT,1strain),respectively.Genotypic and antimicrobial resistance properties of MRSA strains from 96 patients in our hospital were showed in tableⅠin the end of the paper.As a whole,it seems that SCCmec-Ⅲof MRSA is the predominant strain in the hospital.Conclusions:The predominant strain of MRSA isolates was SCCmec-Ⅲgenotype.It suggests strongly that more extensive survey of MRSA should be done and cross-infection control procedure should be reinforced.SCCmec genotyping by multiplex PCR is the powerful epidemiological tool to study the genotyping of MRSA with high sensibility and resolution.
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