金黄色葡萄球菌临床分离株对万古霉素敏感性的监测

Susceptibility of clinical Staphylococcus aureus isolates to vancomycin

目的检测金黄色葡萄球菌（金葡菌）对万古霉素药物敏感情况，以监控对万古霉素敏感性降低金葡菌[vaneomyein-intermediate Staphylococcus aureus（S．aureus），VISA]或耐万古霉素金葡菌（vancomycin-resistant S．aureus，VRSA）的出现，防止其暴发流行。方法对石家庄市区2家三级甲等医院分离自痰液、支气管肺泡灌洗液等临床标本的55株金葡菌应用苯唑西林纸片和头孢西丁纸片检测是否为耐甲氧西林的金葡菌（methieilin-resistant S．aureus，MRSA）；对检出的MRSA，再用胶乳凝集试验检测青霉素结合蛋白2a（PBp-2a）进一步确认。应用Kirb-Bauer纸片法和琼脂稀释法测定万古霉素对55株金葡菌的抑菌环大小和最低抑菌浓度（MIC值），并比较MRSA与对甲氧西林敏感的金葡菌（methieilin-suseeptibility S．aureus，MSSA）的MIC差异。同时对2004～2005年河北医科大学第二医院分离金葡菌的耐药性状况进行了回顾分析。结果55株金葡菌的万古霉素抑菌环直径15～21mm，MIC≤1mg／L，且MRSA与MSSA两组之间差异无统计学意义（P〉0．05）。河北医科大学第二医院2004年、2005年MRSA的检出率分别为56．8％和64．5％。结论石家庄市区医院分离的55株金葡菌中未检出VISA或VRSA，但部分菌株已经接近耐药折点，应密切关注其发展动向；MRSA的耐药机制可能与金葡菌对糖肽类抗生素耐药无直接相关性。

Objective To inspect the emergence of vancomycin-resistant S. aureus （VRSA） or vancomycinintermediate S. aureus（VISA） in Shijiazhuang. And to detect the susceptibility of vancomycin against Staphylococcus aureus（S, aureus） including methicillin-resistant S. aureus（MRSA）. Methods Fifty-five S. aureus strains were isolated from clinical specimen,such as sputum,cerebrospinal fluid from two hospitals in Shijiazhuang city. Thirty strains were selected for MRSA by Kirby-Bauer disk diffusion method with oxacillin and cefoxitin out of 55 isolates and identified by latex agglutination test for the detection of penicillin-blinding protein 2a （PBP 2a）. Minimal inhibitory concentration （MIC） of vancomycin against S. aureus was determined by agar dilution test. In the meantime,all the S. aureus isolated from the hospital during 2004 to 2005 were analyzed for the distribution and isolated rate of MRSA. Results MRSA and methicillin-sensitive S. aureus were all susceptible to vancomycin with a MIC ≤ 1 mg/L. The zone diameter of vancomycin against all 55 trains was from 15-21 mm. There was no significant difference of MIC between 30 MRSA strains and 25 MSSA strains. The occurrence of MRSA was 56.8% in 2004 and 64.5% in 2005, respectively. Conclusion VISA or VRSA are not found in the strains; however, the zone diameter and MIC value are close to the breakpoint. MRSA might not be related to the mechanism of vancomycin resistance.