Evaluation of SD BIOLINE Syphilis 3.0 for Rapid Diagnosis of Syphilis: Report from a Regional Sexually Transmitted Infection Reference Laboratory in North India

BACKGROUND: Serology is considered the mainstay of syphilis diagnosis. The limitations of the traditional serological methods and the advent and availability of novel immunochromatographic assays have led to the widespread application of rapid point-of-care procedures as screening tools for syphilis. However, these tests have not been extensively evaluated. This study was designed to evaluate the performance of a rapid syphilis diagnostic test known as SD BIOLINE Syphilis 3.0 (SD Biostandard Diagnostics Private Limited, Gurgaon, Haryana, India). MATERIALS AND METHODS: A panel comprising of 50 venereal disease research laboratory reactive and 50 nonreactive sera was tested using SD BIOLINE Syphilis 3.0. The performance of the test was evaluated using IMMUTREP Treponema pallidum hemagglutination assay (TPHA) (OMEGA Diagnostics Limited, Scotland, United Kingdom) as the reference standard and sensitivity, specificity, and negative and positive predictive values were calculated. RESULTS: The sensitivity, specificity, and positive and negative predictive values of SD BIOLINE Syphilis 3.0 were 92.86% (confidence interval of 95%: 80.52–98.50%), 98.28% (90.76-99.96%), 97.50% (86.84–99.94%), and 95.00% (86.08–98.96%), respectively, compared to TPHA as the gold standard. CONCLUSION: Keeping in view the high sensitivity and specificity of SD BIOLINE Syphilis 3.0, we conclude that the test can be used as a tool for rapid on-site diagnosis of syphilis and as an alternative to TPHA for detection of antibodies to Treponema pallidum.