应用ROC曲线评价耐甲氧西林葡萄球菌的检测方法

目的：通过对耐甲氧西林葡萄球菌（MRS）的常用检测方法及实验条件进行评价，选择特异性和敏感性较好的方法和理想的实验条件。方法：以PCR法检测葡萄球菌的mecA基因为“金标准”，比较PBP2a胶乳凝集试验法、头孢西丁（FOX）琼脂筛选法、苯唑西林（OXA）琼脂稀释法（MIC）、FOX纸片扩散法、OXA琼脂筛选法、OXA纸片扩散法检测MRS的敏感性和特异性。同时应用ROC曲线对实验方法及不同的实验条件进行评价。结果：PCR法共检出79株mecA基因阳性菌株，阳性率为73．8％。以PCR法为“金标准”，上述6种方法的ROC曲线下面积分别为0．994，0．964，0．955，0．946，0．932，0．862。结论：选择最佳实验条件，用两种表型检测方法作平行检测，对可疑结果用PBP2a胶乳凝集试验或PCR法确诊。

Application of ROC curve in the evaluation of the methods for detection of methicillin-resistant strains of staphylococci

Objective: To evaluate of six tests for detection of methicillin-esistant strains of staphylococci.Then choosed the better methods and conditions for clinical experiment.Methods: To compare the sensitivity and the specificity of the PBP2a latex agglutination method,efoxitin agar screening method,oxacillin agar dilution method(MIC),cefoxitin disk diffusion method,oxacillin agar screening test and oxacillin disk diffusion method for detecting of MRS using PCR amplification mecA gene as "gold standard".Receiver operating characteristic(ROC)curve was drawn,and the area under the curve was calculated. Results: There were 79 isolates showing mecA-positive among 107 staphylococcal isolates by PCR,the rate was 73.8%.The area under ROC curve of the six methods was 0.994,0.964,0.955,0.946,0.932,0.862 respectively. Conclusion: For advancing the sensitivity and the specificity,two methods should be tested simultaneously.If the results were conflicting,the PCR assay or PBP2a latex agglutination test for detection of MRS should be operated.