Standard test for syphilis

Ans. a (VDRL) (Ref. Ananthanarayan Microbiology 7th ed., Fig. 36.2, p. 381)Diagnosis of SYPHILIS# Detection of abs in CSF by FTA-Abs is most specific test for neurosyphilis.# Treponemal ab tests (FTA-Abs, MHATP) measures abs reactive with T. pallidum.Serological Tests for SxphilisThese tests form the mainstay of laboratory diagnosis.These are follows:1. Test for antibodies reacting with cardiolipin antigen reagin tests; standard tests for syphilis; STS2. Tests for antibodies reacting with group-specific treponemal arftigen3. Tests for specific antibodies to pathogenic treponema (T. pallidum).Reagen Antibody Tests (VDRL mainly)# These tests use the lipoid or cardiolipin antigens and are known as 'standard tests for syphilis' or STS.# The first of the reagin antibody test was the Wassermann complement fixation test (1906). It is no longer in use now.- The first flocculation test used widely was tube flocculation test of Kahn.- The Kahn test been replaced by the simpler and more rapid VDRL test, which gives more quantitative result.- VDRL test can be used for testing CSF also, but not plasma. CSF need not be heated prior to test.- A number of modifications of the VDRL have been developed, of which the Rapid Plasma Reagin (RPR) test is the most popular.Sensitivity of Serodiagnostic Tests in Untreated SyphilisMean Percentage Positive (Range) at Indicated Stage of DiseaseTestPrimarySecondaryLatentTertiaryVDRL, RPR78 (74-87)10095 (88-100)71 (37-94)FTA-ABS84 (70-100)10010096TP-PA89100100NA