Performance of the EUCAST Disk Diffusion Method, the CLSI Agar Screen Method, and the Vitek 2 Automated Antimicrobial Susceptibility Testing System for Detection of Clinical Isolates of Enterococci with Low- and Medium-Level VanB-Type Vancomycin Resistance: a Multicenter Study
Performance of the EUCAST Disk Diffusion Method, the CLSI Agar Screen Method, and the Vitek 2 Automated Antimicrobial Susceptibility Testing System for Detection of Clinical Isolates of Enterococci with Low- and Medium-Level VanB-Type Vancomycin Resistance: a Multicenter Study
复制标题
DOI：
10.1128/jcm.03544-13
复制
发表时间：
2014-05-01
影响因子：
9.4
通讯作者：
Sundsfjord, Arnfinn
中科院分区：
文献类型：
--
作者：
Hegstad, Kristin;Giske, Christian G.;Sundsfjord, Arnfinn
在一项斯堪的纳维亚多中心研究（n = 28）中评价了不同的抗菌药物敏感性试验方法，以检测肠球菌的低水平万古霉素耐药性。在丹麦人（n = 5）、挪威人（n = 13）、和瑞典（n = 10）实验室使用EUCAST纸片扩散法（n = 28）和CLSI琼脂筛选法（n = 18）或Vitek 2系统（bioM rieux）（n = 5）。EUCAST圆盘扩散法（非常重大错误[VME]率，7.0%;灵敏度，0.93;重大错误[ME]率，2.4%;特异性，0.98）和CLSI琼脂筛选VME率6.6%，敏感性0.93%，ME率5.6%，特异性，0.94）明显优于Vitek 2系统（VME率，13%;敏感性，0.87; ME率，0%;特异性，1）。EUCAST纸片扩散法的性能受到万古霉素抑菌圈大小差异以及工作人员将模糊抑菌圈边缘解释为万古霉素耐药性指示的经验的挑战。使用Oxoid琼脂（P < 0.0001）或Merck Mueller-Hinton（MH）琼脂（P = 0.027）进行纸片扩散试验的实验室明显优于使用BBLMHII培养基的实验室。使用Difco脑心浸液（BHI）琼脂进行CLSI琼脂筛选的实验室表现明显优于使用Oxoid BHI琼脂的实验室（P = 0.017）。总之，EUCAST纸片扩散法和CLSI琼脂筛选法在检测低水平耐药的VanB型万古霉素耐药肠球菌中的表现均可接受（灵敏度为0.93;特异性为0.94 - 0.98）。重要的是，使用CLSI琼脂筛选需要仔细监测平板中的万古霉素浓度。此外，圆盘扩散方法要求人员接受解释区域边缘的培训。
Different antimicrobial susceptibility testing methods to detect low-level vancomycin resistance in enterococci were evaluated in a Scandinavian multicenter study (n = 28). A phenotypically and genotypically well-characterized diverse collection of Enterococcus faecalis (n = 12) and Enterococcus faecium (n = 18) strains with and without nonsusceptibility to vancomycin was examined blindly in Danish (n = 5), Norwegian (n = 13), and Swedish (n = 10) laboratories using the EUCAST disk diffusion method (n = 28) and the CLSI agar screen (n = 18) or the Vitek 2 system (bioM rieux) (n = 5). The EUCAST disk diffusion method (very major error [VME] rate, 7.0%; sensitivity, 0.93; major error [ME] rate, 2.4%; specificity, 0.98) and CLSI agar screen (VME rate, 6.6%; sensitivity, 0.93; ME rate, 5.6%; specificity, 0.94) performed significantly better (P = 0.02) than the Vitek 2 system (VME rate, 13%; sensitivity, 0.87; ME rate, 0%; specificity, 1). The performance of the EUCAST disk diffusion method was challenged by differences in vancomycin inhibition zone sizes as well as the experience of the personnel in interpreting fuzzy zone edges as an indication of vancomycin resistance. Laboratories using Oxoid agar (P < 0.0001) or Merck Mueller-Hinton (MH) agar (P = 0.027) for the disk diffusion assay performed significantly better than did laboratories using BBLMHII medium. Laboratories using Difco brain heart infusion (BHI) agar for the CLSI agar screen performed significantly better (P = 0.017) than did those using Oxoid BHI agar. In conclusion, both the EUCAST disk diffusion and CLSI agar screening methods performed acceptably (sensitivity, 0.93; specificity, 0.94 to 0.98) in the detection of VanB-type vancomycin-resistant enterococci with low-level resistance. Importantly, use of the CLSI agar screen requires careful monitoring of the vancomycin concentration in the plates. Moreover, disk diffusion methodology requires that personnel be trained in interpreting zone edges.