Ei Richmond Meika, Hoang William, Shuel Michelle, Titus Joshua, Van Caeseele Paul, Stein Derek R, Tsang Raymond Sw
Syphilis Diagnostic Unit, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.
Cadham Provincial Public Health Laboratory, Winnipeg, Manitoba, Canada.
J Assoc Med Microbiol Infect Dis Can. 2024 Jul 19;9(2):82-94. doi: 10.3138/jammi-2023-0035. eCollection 2024 Jun.
Syphilis infections are increasing in Canada, and traditional serological diagnostics pose barriers for vulnerable and marginalized populations at greatest risk. Point-of-care tests (POCTs) offer solutions, yet none were available in Canada until recently. The Chembio Dual Path Platform (DPP) Syphilis Screen & Confirm (SSC) is one of the first POCTs that helps distinguish active infection from non-infectious syphilis. This study evaluates the reliability of the Chembio DPP SSC to diagnose syphilis infection.
One hundred clinical samples with known syphilis serology (chemiluminescent microparticle immunoassay [CMIA] and rapid plasma regain [RPR]) results were used to evaluate the Chembio DPP SSC. CMIA-ve (n = 20), CMIA+ve RPR-ve (n = 40), and CMIA+ve RPR+ve (n = 40) samples represented negative, past, and presumed active infection, respectively. Samples were used in two formats: serum and simulated blood. Two laboratory technicians read the test visually, and with the manufacturer's DPP Micro Reader, in blinded fashion.
Overall sensitivity of the Chembio DPP SSC to distinguish presumed active infection from non-infectious syphilis (past infection and no infection) with visual reads were 52.50% (serum) and 55.00% (simulated blood). Sensitivity increased using the DPP Micro Reader to 90.00% (serum) and 97.50% (simulated blood). Specificity with visual reads were 98.33% (serum) and 95.00% (simulated blood) compared to Micro Reader results of 88.30% (serum) and 80.00% (simulated blood). For the non-treponemal portion of the POCT with visual reads, the sensitivity increased with increasing RPR titers. Low RPR titers <1:4 only had a sensitivity of 42.86% (serum) and 14.29% (simulated blood).
The laboratory evaluation of the Chembio DPP SSC shows promise in detecting active syphilis, particularly in samples with RPR titers >1:4. However, the need for the Micro Reader for more accurate results is a limitation of the POCT, and financial constraints may pose barriers to some users. Further field evaluation is warranted.
梅毒感染在加拿大呈上升趋势，传统血清学诊断方法给风险最高的弱势群体和边缘化人群带来了障碍。即时检验（POCT）提供了解决方案，但直到最近加拿大都没有此类产品。Chembio双路径平台（DPP）梅毒筛查与确认（SSC）检测是首批有助于区分活动性感染与非感染性梅毒的即时检验产品之一。本研究评估了Chembio DPP SSC检测梅毒感染的可靠性。
采用100份梅毒血清学结果已知（化学发光微粒子免疫分析[CMIA]和快速血浆反应素环状卡片试验[RPR]）的临床样本评估Chembio DPP SSC。CMIA阴性（n = 20）、CMIA阳性RPR阴性（n = 40）和CMIA阳性RPR阳性（n = 40）样本分别代表阴性、既往感染和疑似活动性感染。样本采用两种形式：血清和模拟血液。两名实验室技术人员以盲法通过肉眼及使用制造商的DPP微型读数仪读取检测结果。
Chembio DPP SSC通过肉眼读取区分疑似活动性感染与非感染性梅毒（既往感染和未感染）的总体灵敏度在血清样本中为52.50%，在模拟血液样本中为55.00%。使用DPP微型读数仪后，灵敏度在血清样本中提高到90.00%，在模拟血液样本中提高到97.50%。肉眼读取的特异性在血清样本中为98.33%，在模拟血液样本中为95.00%；相比之下，微型读数仪的结果在血清样本中为88.30%，在模拟血液样本中为80.00%。对于POCT的非梅毒螺旋体部分，通过肉眼读取，灵敏度随RPR滴度升高而增加。低RPR滴度<1:4时，血清样本中的灵敏度仅为42.86%，模拟血液样本中的灵敏度仅为14.29%。
对Chembio DPP SSC的实验室评估表明，其在检测活动性梅毒方面具有前景，特别是在RPR滴度>1:4的样本中。然而，需要微型读数仪才能获得更准确的结果是该POCT的一个局限性，财务限制可能会给一些用户带来障碍。有必要进行进一步的现场评估。
