Kirby Institute, University of New South Wales, Sydney.
Victorian Infectious Diseases Reference Laboratory, Melbourne.
Clin Infect Dis. 2015 Jul 15;61(2):184-91. doi: 10.1093/cid/civ243. Epub 2015 Mar 25.
Most syphilis point-of-care (POC) tests detect treponemal antibodies, which persist after successful treatment. Subsequent POC tests are positive, despite no active infection, and can lead to unnecessary treatment. We evaluated a new POC test, incorporating a nontreponemal component, to distinguish active from past infection.
Sera stored at 2 Australian laboratories were tested with DPP Screen and Confirm Assay. Treponemal and nontreponemal test lines were compared to corresponding conventional treponemal and nontreponemal reference test results: immunoassays and rapid plasma reagin (RPR), respectively, with RPR quantification by endpoint titration. POC test outcome concordance with conventional test results was assessed according to serological and clinical categories.
Among 1005 serum samples tested, DPP treponemal line sensitivity was 89.8% (95% confidence interval [CI], 87.3%-91.9%) and specificity was 99.3% (95% CI, 97.0%-99.9%). DPP nontreponemal line sensitivity was 94.2% (95% CI, 91.8%-96.0%) and specificity was 62.2% (95% CI, 57.5%-66.6%). DPP test outcome (pair of test lines) was concordant with both reference test results for 94.3% of 404 high-titer infections, 90.1% of 121 low-titer infections, 27.5% of 211 past/treated infections, and 78.1% of 242 infections classified as not syphilis. Among 211 past/treated infections, 49.8% were incorrectly identified as active infection and a further 22.8% as not syphilis.
DPP test use would result in identification of >93% of active syphilis infections, whereas just over half of past infections would be diagnosed as past or not syphilis, avoiding unnecessary treatment compared with other POC tests. This may be at the expense of missing some active infections; thus, its potential benefits will depend on the prevalence of past vs active infection in a population.
大多数梅毒即时检测（POC）检测方法都能检测到梅毒螺旋体抗体，而这些抗体在成功治疗后仍会持续存在。尽管没有活动性感染，但随后的 POC 检测仍为阳性，可能导致不必要的治疗。我们评估了一种新的 POC 检测方法，该方法结合了非梅毒螺旋体成分，以区分活动性感染和既往感染。
我们对澳大利亚两个实验室储存的血清进行了 DPP Screen 和 Confirm 检测。比较了梅毒螺旋体和非梅毒螺旋体检测线与相应的传统梅毒螺旋体和非梅毒螺旋体参考检测结果：分别为免疫测定和快速血浆反应素（RPR），RPR 定量采用终点滴定法。根据血清学和临床分类，评估 POC 检测结果与传统检测结果的一致性。
在检测的 1005 份血清样本中，DPP 梅毒螺旋体检测线的敏感性为 89.8%（95%置信区间[CI]，87.3%-91.9%），特异性为 99.3%（95%CI，97.0%-99.9%）。DPP 非梅毒螺旋体检测线的敏感性为 94.2%（95%CI，91.8%-96.0%），特异性为 62.2%（95%CI，57.5%-66.6%）。在 404 例高滴度感染、121 例低滴度感染、27.5%既往/治疗感染和 78.1%非梅毒感染的 242 例感染中，DPP 检测结果（检测线对）与两种参考检测结果的一致性分别为 94.3%、90.1%、27.5%和 78.1%。在 211 例既往/治疗感染中，49.8%被错误地诊断为活动性感染，另有 22.8%被诊断为非梅毒。
与其他 POC 检测方法相比，DPP 检测方法的使用将能识别出超过 93%的活动性梅毒感染，而超过一半的既往感染将被诊断为既往感染或非梅毒，从而避免不必要的治疗。但这可能会导致错过一些活动性感染；因此，其潜在的益处将取决于人群中既往感染与活动性感染的流行率。
