Antimicrobial resistance features and molecular typing of clinically isolated methicillinresistant Staphylococcus aureus

Abstract:

ObjectiveTo study antimicrobial resistance and genotyping of methicillinresistant Staphylococcus aureus (MRSA). MethodsA total of 967 norepetitive strains of Staphylococcus aureus (S. aureus) isolated from a hospital between January 2014 and November 2015 were collected, antimicrobial susceptibility testing, mecA gene, and PantonValentine leukocidin gene (PVL gene) were detected; staphylococcal cassette chromosome mec（SCCmec） typing, multilocus sequence typing（MLST）, S. aureus protein A（spa） gene typing, and S. aureus accessory gene regulator(agr) typing were performed with multiplex polymerase chain reaction. ResultsOf 967 strains of S. aureus，210 (21.72%) were MRSA; detection rate of MRSA from sputum specimen was higher than that of skin and soft tissue specimen(68.09% vs 11.83%, P<0.05); vancomycin and linezolidresistant S. aureus strains were not found, susceptibility rates of MRSA to gentamicin, tetracycline, erythromycin, clindamycin, levofloxacin, ciprofloxacin, moxifloxacin, nitrofurantoin, and rifampicin were all lower than those of methicillinsensitive Staphylococcus aureus (MSSA), differences were all statistically significant（all P＜0.05）；antimicrobial susceptibility rate of MRSA to compound sulfamethoxazole was higher than MSSA, difference was significant(P<0.05). Susceptibility rates of MRSA isolated from skin and soft tissue to gentamicin, levofloxacin, ciprofloxacin, moxifloxacin, and rifampicin were 86.90%-95.24%，while MRSA isolated from sputum were only 1.56%-15.63%. Of 967 strains of S. aureus, 210 harbored mecA gene, 10 harbored PVL gene, 8(3.81％) of 210 MRSA strains weren’t typed. The main types of MLST, SCCmec, spa, and agr were ST 239 (n=177 strains), type Ⅲ(n=177 strains), t 030 (n=177 strains), and typeⅠ(n=196 strains) respectively. ConclusionThe main epidemic clone of MRSA strain in this hospital is ST239MRSASCCmec IIIt030, antimicrobial resistance is serious, monitoring on drugresistant strains in hospital should be strengthened.