Implementation of the reverse screening syphilis algorithm in a clinical laboratory

Abstract

Background: Syphilis remains a public health concern worldwide, the accuracy of diagnostic tests is critical for its successful control. Currently, there are two approaches to the diagnosis of syphilis using serological tests: the traditional algorithm and the reverse algorithm. Aim: The goal of this study was to analyse the advantages and disadvantages in the implementation of the syphilis reverse-screening algorithm in an outpatient clinical laboratory. Methods: An observational cross-sectional study was carried out analyzing 246 reactive sera from a total of 14700 requests for syphilis serology. Chemiluminescent assay ARCHITECT Syphilis TP, V.D.R.L. and FTA-Abs were performed. Results: Among 246 reactive sera by ARCHITECT Syphilis TP, 129 were reactive and 117 were non-reactive by V.D.R.L. the last mentioned resulted in 97 reactive and 20 non-reactive by FTA-Abs, suggesting false positives (0.13%).Two patients with primary infection were detected, that were not detected by V.D.R.L. and one pregnant woman with primary infection with a high value S/CO and V.D.R.L.:1 dils. Conclusions: Among the advantages of using a reverse algorithm were greater sensitivity in the detection of patients with primary syphilis; automation, complete traceability of the samples; objective interpretation and conclusive results.