Genotyping and Drug Resistance Analysis of Methicillin-resistant Staphylococcus Aureus SCCmec

OBJECTIVE To analyse genotyping and drug resistance of methicillin-resistant Staphylococcus aureus (MRSA) SCCmec isolated in Taizhou Traditional Chinese and Western Medicine Hospital, and to provide reference for diagnosis and treatment of clinical MRSA infection. METHODS The 297 strains of Staphylococcus aureus(SA) isolated from clinical specimens in hospital where author work in were studied from January 2017 to December 2018, and MRSA were screened according to the drug sensitivity test of cefoxitin. The MRSA and SCCmec were identified and genotyped by PCR. The resistance of different SCCmec genotypes was analyzed by K-B disk diffusion method. RESULTS The 127 strains were positive by MRSA screening test in 297 SA strains. The positive rate of primary screening test was 42.76%. There were 121 positive strains in 127 primary screening positive strains by mecA gene test. The positive rate of MRSA confirmation test was 40.74%, and the coincidence rate of phenotype and genotype detection was 95.28%. SCCmec typing of MRSA:77 strains were SCCmec type Ⅲ, 34 strains were SCCmec type Ⅱ, and 3 strains were SCCmec type Ⅳ. Seven strains could not be classified by this method. Drug susceptibility test showed that SCCmec type Ⅱ and SCCmec type Ⅲ strains were 100% sensitive to vancomycin and teicoplanin, but 100% resistant to beta-lactam antibiotics. The resistance rate of SCCmec type Ⅲ strain to quinolones, macrolides, tetracyclines and lincomycin was significantly higher than that of SCCmec type Ⅱ strain, and the difference was statistically significant. CONCLUSION The main epidemic strain of MRSA isolated from clinical specimens in hospital where author work in is SCCmec type Ⅲ. The drug resistance of MRSA is serious, manifesting as multi-drug resistance.