Genetical and epidemiological analysis of enterococci resistant to vancomycin

本研究旨在评估日本现有的区分万古霉素耐药肠球菌（VRE）和敏感肠球菌（VSE）分离株的检测方法。在所评估的表型检测方法中，使用Mueller-Hinton琼脂中8杯/ ml万古霉素的琼脂筛选方法具有足够的准确性，检测VRE的灵敏度为98.3%，特异性为100%。同时，所有VRE分离株在孵育48小时后读取结果时，通过E试验解释为耐药或中间。然而，两种圆盘扩散试验（Showa圆盘和基于nccls的seni -disc）均无法区分VRE和VSE，特别是无法区分vanB阳性和阴性分离株。自动系统，Vitek GPS-TA产生非常严重的错误的高频率；vanA阳性8.7%，vanB阳性58%。来自日本多个实验室的7个不同种类的1214株肠球菌分离株首次在琼脂筛选试验板上进行了测试，但没有一株分离株表现出表型万古霉素耐药性。

The study was conducted to evaluate the test methods available in Japan to discriminate between the isolates of enterococci resistant to vancomycin (VRE) and those susceptible (VSE). Among the phenotypic test methods evaluated, an agar screening method which utilized 8 mug per ml of vancomycin in Mueller-Hinton agar appeared to have a sufficient accuracy, the results indicating 98.3% of sensitivity and 100% of specificity to detect VRE.Also, all the VRE isolates were interpreted as being resistant or intermediate by the E test when the results were read after 48 hr-incubation. Whereas, two disk diffusion tests, Showa disk and NCCLS-based Sensi-disc, were evaluated, but both failed to discriminate between VRE and VSE,in particular, between the isolates with vanB positive and negative. The automated system, Vitek GPS-TA produced high frequencies of very majior errors ; 8.7% for vanA positives and 58% for vanB positives.A total of 1,214 enterococcal isolates from multisite laboratories in Japan, comprising 7 different species, were first tested onto agar screening test plates, but none of isolates represented phenotypic vancomycin resistance.