胶体金法评估血清百日咳毒素抗体IgG水平的初步研究

Preliminary study on the colloidal gold method to evaluate the lserum pertussis toxin antibody IgG

目的:评估胶体金法判断血清百日咳毒素抗体IgG(PT-IgG)水平的准确性。方法:按送检倒序时间从首都医科大学附属北京儿童医院冻存于零下30℃的血清样本中连续选取6个月内的PT-IgG浓度结果(ELISA检测)<20 IU/ml和≥20 IU/ml的标本各100份,排除1份标本量不足标本,最终纳入199份标本作为研究对象。两组检测人员分别采用ELISA试剂盒和胶体金法(阳性检测界值分别为20 IU/ml和80 IU/ml)检测PT-IgG浓度,评估后者检测浓度范围与ELISA检测结果的一致性。结果:以ELISA检测结果为参照标准,检测界值为20 IU/ml的胶体金法检测的敏感度和特异度分别为76.2%(80/105)和95.7%(90/94),阳性预测值和阴性预测值分别为95.2%(80/84)和78.3%(90/115),约登指数为0.7。检测界值为80 IU/ml的胶体金法检测的敏感度和特异度分别为100.0%(23/23)和69.9%(123/176),阳性预测值和阴性预测值分别为30.3%(23/76)和100.0%(123/123),约登指数为0.7。结论:以ELISA检测结果为参照标准,以20 IU/ml为检测界值的胶体金法的检测特异度和阳性预测值均较高,阳性结果较为可靠,表明机体有一定水平的百日咳免疫;而检测界值为80 IU/ml的胶体金法检测的敏感度和阴性预测值较高,可结合临床用于排除百日咳急性或近期感染。

Objective:To evaluate the accuracy of colloidal gold method in the determination of serum anti-pertussis toxin IgG(PT-IgG).Methods:Samples with PT-IgG concentration<20 IU/ml(n=100)and≥20 IU/ml(n=100)within 6 months were selected continuously from the serum samples frozen at-30℃from Beijing Children’s Hospital affiliated to Capital Medical University in the reverse order,and one sample with insufficient quantity was excluded.Finally,199 samples were included.ELISA kit and colloidal gold method(the positive detection limit was 20 IU/ml and 80 IU/ml)were used to detect the concentration of PT-IgG in the two groups,respectively,and the consistency between the concentration range of the colloidal gold method and the results of ELISA was evaluated.Results:Taking the results of ELISA as the standard,the sensitivity and specificity of colloidal gold strip with the detection limit of 20 IU/ml were 76.2%(80/105)and 95.7%(90/94),respectively;the positive predictive value and the negative predictive value were 95.2%(80/84)and 78.3%(90/115),and Youden index was 0.7.The sensitivity and specificity of colloidal gold strip with the detection limit of 80 IU/ml were 100.0%(23/23)and 69.9%(123/176);the positive predicted value and the negative predictive value were 30.3%(23/76)and 100.0%(123/123),and Youden index was 0.7.Conclusion:Taking the results of ELISA as the standard,the colloidal gold method with 20 IU/ml as the detection limit has high specificity and positive predictive value,and the positive results are reliable,which indicates that the body has a certain level of pertussis immunity.However,the colloidal gold method with the detection limit of 80 IU/ml has high sensitivity and negative predictive value,which can be used to exclude acute or recent pertussis infection in combination with clinical practice.