金黄色葡萄球菌对万古霉素敏感性试验方法评价

目的比较不同方法检测金黄色葡萄球菌对万古霉素敏感性试验结果。方法将1株从临床标本中分离的异质性耐万古霉素的金黄色葡萄球菌(h-VRSA)在含有不同浓度的万古霉素培养基上连续转种诱导,得到一系列对万古霉素不同程度耐药的菌株,分别用琼脂筛选法、微量肉汤稀释法、E-test法、纸片扩散法和仪器法对万古霉素的敏感性进行检测。结果琼脂筛选法、微量肉汤稀释法和E-test法可以检测出金黄色葡萄球菌对万古霉素中介耐药(VISA),而纸片扩散法和仪器法则不能检出VISA。结论微量肉汤稀释法和E-test法是检测金黄色葡萄球菌对万古霉素敏感性可接受的方法。若以纸片扩散法和仪器法为常规药敏试验的实验室,应增加含6μg／ml的万古霉素脑心浸液琼脂进行筛查,以加强对VRSA和VISA的监测。

Evaluation of methods for detecting susceptibility of Staphylococcus aureus to Vancomycin

Objective To investigate the effective methods for detecting the susceptibility of Staphylococcus aureus to Vancomycin. Methods An isolate of h-VRSA (heterogeneous Vancomycin-resistant Staphylococcus aureus) isolated from clinical specimen was inoculated on the increasing concentration of vancomycin agars. Varied degree of vancomycin of resistant S. aureus were obtained. The susceptibilities of these S. aureus to vancomycin were tested by agar screening test, broth microdilution method, E-test, disk diffusion method and automated methods. Results Agar screening test, broth microdilution method and E-test are effective for detection of vancomycin-intermediate S. aureus VISA, but disk diffusion and automated methods could not detect VISA. Conclusion Broth microdilution method and E-test are acceptable methods for susceptibility testing of S. aureus to vancomycin. The laboratories using automated methods and disk diffusion method as routine susceptibility test should consider adding a vancomycin agar screen plate to enhance detection of VRSA and VISA.