Multiplex PCR for rapid identification of genotypes of Staphylococcal chromosomal cassette mec in methicillin-resistant Staphylococcus aureus strains

Objective To identify the genotypes of Staphylococcal chromosomal cassette mec(SCCmec) in the isolates of methicillin-resistant Staphylococcus aureus(MRSA) by multiplex polymerase chain reaction(PCR). Methods 112 isolates of Staphylococcus aureus were isolated from various clinical specimens from Feb.2005 to Jul.2005 in our hospital. PCR was used for detecting mecA gene in Staphylococcus aureus. The genotypes and subgenotypes of SCCmec were determined by multiplex PCR. The antimicrobial susceptiblity test was proceeded by automated Microbiology Analyzer. Results 72 of 112(64.3%) Staphylococcus aureus were MRSA with mecA gene positive. The positive rates of SCCmecⅢ and SCCmecⅢA were 68.1%(49/72) and 20.8%(15/72). H16 and H56 were SCCmecⅡ. Only one isolate was SCCmecⅣ. 5 MRSA strains were non-typeable. The isolates with SCCmecⅡ、SCCmecⅢ or SCCmecⅢA were multi-resistant to antibiotics.H19 with SCCmecⅣ was susceptible to all antibiotics except β lactams. Conclusion SCCmecⅢ and SCCmecⅢA are major genotypes in MRSA in Wenzhou area, China. Multiplex PCR is rapid, robust and capable of identifying the genotypes and subgenotypes of SCCmec in MRSA. The isolates with SCCmecⅡ, SCCmecⅢ or SCCmecⅢA are multi-resistant to antibiotics.