Abstract
Background: Our study aimed to reveal the seroprevalence of syphilis in HIV-positive patients in our center and to reveal the diagnostic performance of the reverse sequence algorithm
Materials and Methods: The study data were obtained retrospectively. Statistical analyses were carried out using SPSS version 20.0. Screening for syphilis was performed by reverse sequence algorithm using chemiluminescent microparticle immunoassay (CMIA), Rapid Plasma Reagin and T.pallidum hemagglutination tests.
Results: A total of 91 HIV-positive patients were included in the study. Of these patients, 15 (16.48%) had never been tested for syphilis, and the rate of the patients who have a proper follow-up for syphilis was only 36.17%. Nineteen patients were diagnosed with syphilis; the overall syphilis rate was 20.88%. The mean time to the diagnosis of syphilis was 9.89±13.5 months, ranging from 0 to 48 months. Of the 76 patients screened for syphilis, 19 (25%) had CMIA positivity with concurrent RPR positivity. Concurrent TP-HA testing was performed in 54 (71.05%) of the 76 patients and 17 (89.4%) of 19 patients with CMIA positivity, and all of these patients with CMIA positivity revealed positive TP-HA results.
Conclusions: Syphilis co-infection rate in HIV-positive patients in our hospital was high. However, there are still deficiencies in the screening of syphilis, and it has been shown that a specific screening algorithm is not adopted by the clinicians who follow-up HIV-positive patients. Besides, non-treponemal and treponemal tests in the reverse sequence algorithm revealed reliable results in the diagnosis of syphilis in HIV-infected patients.

Key words: HIV, syphilis, reverse sequence diagnostic algorithm, chemiluminescent immunoassay, RPR, Treponema pallidum hemagglutination assay