Verma Shiva, Panda Pragyan Swagatika, Muralidhar Sumathi, Rajan Santhosh, Khunger Niti
Department of Microbiology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India.
Department of Microbiology, Era's Lucknow Medical College, Lucknow, Uttar Pradesh, India.
Indian J Sex Transm Dis AIDS. 2025 Jan-Jun;46(1):25-30. doi: 10.4103/ijstd.ijstd_132_24. Epub 2025 Jun 9.
Syphilis diagnosis can be confirmed by two testing algorithms. In the traditional algorithm, a nontreponemal test is used as a screening test to rule out syphilis which, if reactive, is confirmed by a treponemal test. In the reverse algorithm, a treponemal test is used as a screening test, which, if positive, is confirmed by a nontreponemal test. If the nontreponemal is negative, a second treponemal assay of a different principle is performed to resolve the discordant result. The aim of this study was to compare the traditional and reverse algorithms for the diagnosis of syphilis in a National Referral Apex Centre for Sexually Transmitted Infections.
A retrospective study was done on samples received from male and female sexually transmitted infection clinics for syphilis testing. All samples were tested simultaneously using the Venereal Disease Research Laboratory (VDRL), hemagglutination assay (TPHA), and fluorescent treponemal antibody absorption (FTA-Abs) test. The results of syphilis serological testing were interpreted using the traditional and reverse algorithms. The traditional algorithm used VDRL as the screening test and TPHA as the confirmatory test. In the reverse algorithm, TPHA was the screening test, and reactive results were confirmed with VDRL. Discordant samples were confirmed with the FTA-Abs test.
The reverse algorithm showed a significantly higher seroprevalence of syphilis than the traditional algorithm (62.4% vs. 40.8%, < 0.0001). The traditional algorithm had a high missed serodiagnosis rate (34.6%) and showed a higher false-positive rate of the screening test (6.8%) as compared to the reverse algorithm (0.6%).
This study supports the use of reverse algorithms for diagnosing syphilis in high-prevalence populations.
梅毒诊断可通过两种检测算法来确认。在传统算法中，非梅毒螺旋体试验用作筛查试验以排除梅毒，若结果呈反应性，则通过梅毒螺旋体试验进行确认。在反向算法中，梅毒螺旋体试验用作筛查试验，若结果为阳性，则通过非梅毒螺旋体试验进行确认。如果非梅毒螺旋体试验为阴性，则采用另一种原理的梅毒螺旋体检测法来解决结果不一致的问题。本研究的目的是在一家全国性性传播感染转诊顶尖中心比较传统算法和反向算法在梅毒诊断中的应用。
对从男性和女性性传播感染诊所接收的用于梅毒检测的样本进行了一项回顾性研究。所有样本同时使用性病研究实验室（VDRL）试验、血凝试验（TPHA）和荧光梅毒螺旋体抗体吸收（FTA-Abs）试验进行检测。梅毒血清学检测结果采用传统算法和反向算法进行解读。传统算法使用VDRL作为筛查试验，TPHA作为确证试验。在反向算法中，TPHA是筛查试验，反应性结果用VDRL进行确认。结果不一致的样本用FTA-Abs试验进行确认。
反向算法显示的梅毒血清流行率显著高于传统算法（62.4%对40.8%，<0.0001）。传统算法的血清学漏诊率较高（34.6%），且与反向算法（0.6%）相比，其筛查试验的假阳性率更高（6.8%）。
本研究支持在高流行人群中使用反向算法诊断梅毒。
