Karaca Yilmaz, Cöplü Nilay, Gözalan Ayşegül, Oncül Ozgür, Akin Levent, Esen Berrin
Refik Saydam Hifzissihha Merkezi Başkanligi, Salgln Hastaliklar Araştirma Müdürlügü, Ankara.
Mikrobiyol Bul. 2010 Jan;44(1):35-45.
Serological methods are widely used for the laboratory diagnosis of syphilis or for screening purposes. The aim of this study was to determine an algorithm for the application of laboratory tests that will provide accurate diagnosis of syphilis in a cheap, fast and practical way. A total of 162 serum samples were evaluated by the following tests: VDRL (Venereal Disease Research Laboratory; Omega Diagnostic, UK), TPHA (Treponema pallidum Hemagglutination Test; Omega Diagnostic, UK), ELISA IgG + IgM (Enzyme Linked Immunosorbent Assay; DiaPro Diagnostic Bioprobes, Italy), FTA-ABS (Fluorescent Treponemal Antibody-Absorption; IgG, Euroimmun, Germany) and WB (Western Blot; IgG Euroimmun, Germany). When the gold standard was considered as FTA-ABS test, the sensitivity, specificity, positive and negative predictive values for VDRL were 77.1%, 100% 100% an 80.6%; for TPHA were 92.8%, 98.7%, 98.7% and 92.9%, for ELISA 98.8%, 98.7%, 98.8% and 98.7%, and for WB 98.8%, 100%, 100% and 98.7%, respectively. When the results of screening with VDRL together with TPHA were compared with FTA-ABS, it was observed that if both VDRL and TPHA results were positive, then there was 100% concordance between the tests. However, when both of the test results were negative, 1.3% of them yielded positive result with FTA-ABS. If either one of VDRL or TPHA results were positive (n = 24), 95.8% (n = 23) was positive with FTA-ABS. Therefore, inconsistent results obtained by VDRL and TPHA requires verification by another method. When ELISA or WB tests were used, the borderline results need verification, however, positive or negative results would be reported. The determination of an algorithm for laboratory tests also depend on the number of patients, cost, cost per positive patient and workload of the laboratory. Thus, ELISA could be selected when the number of cases is high and the results should be reported unless they are suspicious. When the number of cases is low, VDRL/TPHA should be selected, and the results should be verified if they are inconsistent. However, the demographic characteristics of patient groups are also important in test selection and work flow. False positive results are troublesome in case of marriage pre-screening and false negative results in sex workers. When all these factors are taken into consideration it may be suggested that either ELISA or VDRL together with TPHA should be performed and the results should be confirmed by a reference test in case of borderline results in ELISA or inconsistency between VDRL and TPHA results. Although screening for syphilis in the setting of blood banking is a matter of debate, if it is to be performed, then ELISA would be better since the work load is high. In case of pregnancy inconsistent VDRL and TPHA results should be verified since no risk could be afforded.
血清学方法广泛用于梅毒的实验室诊断或筛查。本研究的目的是确定一种实验室检测应用算法，以便以廉价、快速且实用的方式准确诊断梅毒。通过以下检测对总共162份血清样本进行了评估：性病研究实验室玻片试验（VDRL；英国欧米茄诊断公司）、梅毒螺旋体血凝试验（TPHA；英国欧米茄诊断公司）、酶联免疫吸附测定IgG + IgM（ELISA；意大利迪亚普罗诊断生物探针公司）、荧光密螺旋体抗体吸收试验（FTA - ABS；德国欧蒙公司IgG）以及免疫印迹法（WB；德国欧蒙公司IgG）。当将FTA - ABS试验视为金标准时，VDRL的灵敏度、特异性、阳性预测值和阴性预测值分别为77.1%、100%、100%和80.6%；TPHA的分别为92.8%、98.7%、98.7%和92.9%，ELISA的分别为98.8%、98.7%、98.8%和98.7%，WB的分别为98.8%、100%、100%和98.7%。当将VDRL与TPHA的筛查结果与FTA - ABS进行比较时，观察到如果VDRL和TPHA结果均为阳性，则检测之间的一致性为100%。然而，当两项检测结果均为阴性时，其中1.3%的样本FTA - ABS检测结果为阳性。如果VDRL或TPHA结果中有一项为阳性（n = 24），FTA - ABS检测结果为阳性的比例为95.8%（n = 23）。因此，VDRL和TPHA获得的不一致结果需要通过另一种方法进行验证。当使用ELISA或WB检测时，临界结果需要验证，但阳性或阴性结果将予以报告。实验室检测算法的确定还取决于患者数量、成本、每个阳性患者的成本以及实验室的工作量。因此，当病例数量较多且结果除非可疑否则应报告时，可选择ELISA。当病例数量较少时，应选择VDRL/TPHA，且如果结果不一致应进行验证。然而，患者群体的人口统计学特征在检测选择和工作流程中也很重要。在婚前筛查中假阳性结果很麻烦，而在性工作者中假阴性结果很麻烦。当考虑到所有这些因素时，可能建议要么进行ELISA，要么进行VDRL与TPHA联合检测，并且如果ELISA出现临界结果或VDRL与TPHA结果不一致，应通过参考检测来确认结果。尽管在血库环境中进行梅毒筛查存在争议，但如果要进行筛查，那么由于工作量大，ELISA会更好。在怀孕情况下，如果VDRL和TPHA结果不一致，应进行验证，因为不能冒任何风险。
