万古霉素对金黄色葡萄球菌体外抗菌活性研究

Survey on resistance of the isolates of Staphylococcus aureus to Vancomycin in vitro

目的调查万古霉索对金黄色葡萄球菌的体外抗菌活性。方法收集温州医学院附属第一医院2005年2～7月从临床各种标本分离的金黄色葡萄球菌112株，PCR检测mecA基因确定MRSA，采用琼脂稀释法和全自动微生物分析仪检测金黄色葡萄球菌万古霉素MIC值，使用4mg／L万古霉索脑心浸液琼脂（BHIA）筛选异质性耐万古霉素金黄色葡萄球菌（hVRSA）。结果MRSA的检出率为64．3％，万古霉素的MIC大多数≤2mg／L，MIC。为2mg／L，有2株菌在4mg／L万古霉素BHIA平皿上生长，经菌群分析法证实非hVRSA。仪器法检测的万古霉素MIC值与琼脂稀释法的符合率只有35．7％，琼脂稀释法万古霉索MIC高于仪器法，仪器法检测的2株万古霉素中介耐药的菌株经琼脂稀释法和K-B法证实为敏感株。有6株对万古霉索的MIC为4mg／L，按美国NCCLS／CLSI2006年的标准被确定为万古霉素中介耐药株。结论万古霉素对金黄色葡萄球菌具有较强的体外抗菌活性，未发现耐药株，但MIC值较大。仪器法检测金黄色葡萄球菌对万古霉素的敏感性结果不可靠。按NCCLS／CLSI2006年的标准临床上能检测到对万古霉素中介耐药的金黄色葡萄球菌临床分离株。

Objective To investigate the anti-bacterial activity of vancomycin to the isolates of Staphylococcus aureus. 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. Posititve for mecA gene was referred as MRSA. The MICs of vancomycin were determined by agar dilution test and automated microbiology analyzer. HVRS were screened by population analysis method. Results 72 of 112（ 64.3% ） Staphylococcus aureus were referred as MRSA. The MICs of most of them were ≤2 mg/L. MIC90 of vancomycin to the isolates was 2 mg/L. 2 isolates grew on BHIA medium containing 2 mg/L. But they were not hVRSA. The concordance rates of the MICs of agar dilution test and automated microbiology analyzer was 35. 7%. The MICS of vancomycin to 13 isolates were 4 mg/L. 13 isolates above were intermediated to vancomycin NCCLS/CLSI. Conclusions Vancomycin had high anti -bacteria activity to multiresistant Staphylococcus aureus. No isolate of Staphylococcus aureuz was reststant to vancomycin. Automated microbiology analyzer could not determine MICs of vancomycin to Staphylococcus aureus correctly.