Genetical and epidemiological analysis of enterococci resistant to vancomycin

本研究旨在评估日本可用于区分耐万古霉素肠球菌(VRE)和敏感肠球菌(VSE)的检测方法。在所评价的表型试验方法中，在Mueller-Hinton琼脂中使用每毫升8杯万古霉素的琼脂筛选方法似乎具有足够的准确性，检测VRE的敏感性为98.3%，特异性为100%。此外，当培养48小时后读取结果时，所有VRE分离物被E试验解释为耐药或中间。然而，两种纸片扩散试验，Showa纸片和基于NCCLS的Sensi-Disc，都未能区分VRE和VSE，特别是对vanB阳性和阴性的分离株。自动化系统VITEK GPS-TA产生高频率的主要错误；VANA阳性8.7%，VANA阳性58%。来自日本多个实验室的包括7个不同物种的1214株肠球菌首次在琼脂筛选板上进行检测，但没有一株分离株表现出对万古霉素的耐药性。

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.