尿素解离法纠正化学发光法检测梅毒螺旋体抗体假阳性结果的效能评价

Efficiency of urea dissociation method on correcting false-positive anti-Treponema pallidum detected by chemiluminescence assay

目的观察化学发光法检测梅毒螺旋体抗体(anti-Treponema pallidum,anti-TP)假阳性结果的分布情况,探讨尿素解离法纠正化学发光法检测假阳性结果的效能。方法化学发光法检测血清anti-TP为1.00~<20.00 COI并行梅毒螺旋体明胶颗粒凝集试验、甲苯胺红不加热血清试验检测的血清样本409份,随机选取21份血清样本为实验组(8份既往梅毒感染患者血清样本,7份活动期梅毒感染患者血清样本和6份anti-TP假阳性血清样本),余388份为验证组(161份既往梅毒感染患者血清样本,177份活动期梅毒感染患者血清样本和50份anti-TP假阳性血清样本)。采用尿素解离法联合化学发光法检测实验组血清样本anti-TP含量,确定最佳尿素解离浓度,计算样本亲和指数(avidity index,AI)。以含0 mol/L和最佳尿素解离浓度的化学发光法anti-TP检测试剂盒检测验证组血清样本anti-TP含量,计算AI并确定AI阈值。以梅毒螺旋体明胶颗粒凝集试验为金标准,计算尿素解离法联合化学发光法诊断anti-TP阳性的灵敏度和特异度。结果anti-TP假阳性结果分布于1.00~<15.00 COI范围内,且假阳性率随anti-TP检测值降低而逐渐升高。尿素解离浓度为6.0 mol/L时,验证组既往梅毒感染患者血清样本的AI为0.370~0.714,活动期梅毒感染患者血清样本的AI为0.351~0.809,anti-TP假阳性患者血清样本的AI为0.028~0.360。以0.350为AI阈值,尿素解离法联合化学发光法诊断anti-TP阳性的灵敏度为100.00%,特异度为96.00%。结论尿素解离法可纠正化学发光法检测anti-TP假阳性结果。

Objective To investigate the distribution of false-positive anti-Treponema pallidum(anti-TP)detected by chemiluminescence assay(CLIA),and to evaluate the efficiency of urea dissociation method on correcting CLIA false-positive anti-TP.Methods Totally 409 serum samples with anti-TP of 1.00 to<20.00 COI detected by CLIA were subjected to TP particle agglutination test(TPPA)and tolulized red unheated serum test,and were divided into 21 serum samples(training group)including 8 samples from patients with previous syphilis infection,7 serum samples from patients with active syphilis infection and 6 false-positive anti-TP serum samples,and 388 serum samples(validation group)including 161 serum samples from patients with previous syphilis infection,177 serum samples from patients with active syphilis infection and 50 false-positive anti-TP serum samples.The level of serum anti-TP in training group was detected by urea dissociation method combined with CLIA to determine the optimal urea dissociation concentration and calculate the sample avidity index(AI).The levels of anti-TP in serum of validation group were detected with anti-TP test kits containing 0 mol/L and the optimal urea dissociation concentration,the AI was calculated and the AI threshold was determined.Taking TPPA as the gold standard,the sensitivity and specificity of urea dissociation method combined with CLIA in the diagnosis of anti-TP positive were calculated.Results The false-positive anti-TP was distributed in the range of 1.00 to<15.00COI,and the false-positive rate increased gradually with the decrease of anti-TP detection value.When the urea dissociation concentration was 6.0mol/L,the AI of serum from patients with previous syphilis infection in validation group was 0.370to 0.714,from patients with active syphilis infection was 0.351to 0.809,and from patients with false positive anti-TP was 0.028 to 0.360.Taking 0.350as the AI threshold,the sensitivity and specificity of urea dissociation combined with CLIA in the diagnosis of anti-TP were 100.00% and 96.00%,respectively.Conclusion Urea dissociation method can effectively correct false-positive anti-TP detected by CLIA.