Study on SCCmecmolecular epidemiology of methicillin-resistant coagulase-negative Staphylococci

OBJECTIVE To investigate the distribution of chromosome mec gene cassette of coagulase-negative Staphylococci isolated from the hospital so to provide the reasonable basis for the clinical molecular epidemiological investigations of coagulase-negative Staphylococci.METHODS A total of 98 strains of coagulase-negative Staphylococci were isolated from various clinical specimens from Jun 2011 to Jun 2012.MecA gene was also determined by PCR.The antimicrobial susceptibility was measured by agar diffusion method.SCCmec typing was conducted using a novel multiplex PCR assay allowing for concomitant detection of methicillin resistance(mecA gene) to facilitate detection and classification of all currently described SCCmec typesⅠ,Ⅱ,Ⅲ,Ⅳa,b,c,d andⅤ.RESULTS MecA gene was positive in all the strains.Among the 98 methicillin-resistant isolates,there were 40 Staphylococcus epidermidis isolates,32 Staphylococcus haemolyticus isolates,21 Staphylococcus hominis isolates,and 5 Staphylococcus cohnii isolates.There were 24(60.0%) SCCmec Ⅴtype,9(22.5%) SCCmec Ⅳ type and 6(15.0%) SCCmec Ⅰ type among 40 S.epidermidis isolates,including 5 SCCmec IVa types and 4 SCCmec IVb types.A strain of S.epidermidis was untyped.There were 16(68.75%) SCCmec Ⅴtype,6(15.0%) SCCmec Ⅲ type,and 10(31.25%) SCCmec Ⅳ type in 32 methicillin-resistant S.hemolytic isolates,including 5 SCCmec Ⅳa types and SCCmec Ⅳb types.SCCmec Ⅴwas identified in all methicillin-resistant S.hominis and S.cohnii isolates.CONCLUSION SCCmecⅤ and SCCmec Ⅳ are the major genotypes of MRCNS in the hospital.There are several different SCCmec types among several kinds MRCNS.