Drug resistance of Staphylococcus aureusin 2011

OBJECTIVE To investigate the drug resistance of Staphylococcus aureus in 2011 so as to provide basis for the rational use of antibiotics.METHODS The antimicrobial susceptibility testing was carried out by means of Kirby-bauer(KB),the minimum inhibitory concentration(MIC) of vancomycin for methicillin-resistant S.aureus(MRSA) was determined by using E-test,and the data were analyzed by Whonet 5.6 software according to CLSI 2010 breakpoint.RESULTS A total of 255 strains of S.aureus were isolated,among which the MRSA strains accounted for 51.4%.The highest prevalence of MRSA was found in neurosurgery ward(85.4%)and ICU(80.1%),the lowest in outpatient department(15.2%).The methicillin-sensitive S.aureus(MSSA) strains showed high degree of resistance to penicillin,and 41.7% to erythromycin,highly sensitive to the rest of antibacterial drugs with the drug susceptibility rate higher than 70.0%.The resistance rate of the MRSA was significantly higher than that of the MSSA.The MRSA strains showed 100.0% susceptible to vancomycin,linezolid and teicoplanin,followed by 92.0% to sulfamethoxazole-trimethoprim and 80.4% to rifampicin.The E-test results showed that the MIC50 and MIC90 of vancomycin against the MRSA strains were 1.0μg/ml and 2.0 μg/ml,respectively.44.3% of the MRSA strains had a vancomycin MIC more than 1.0 μg/ml,but no strains of vancomycin-sensitive strains were found.CONCLUSION Neurosurgery ward and ICU have high prevalence of MRSA infection,MRSA strains were highly resistant to most antibiotic agents,the monitoring of vancomycin MIC for MRSA should be paid more attention.