Confirmatory test for Syphilis is:
September 2010 March 2013
a) VDRL
b) Rapid plasma reagin test
c) FT-ABS
d) All of the above
Correct Answer - C
Ans. C: FT-ABS
T. pallidum cannot be grown in vitro
Diagnostic tests for syphilis: Tests include serologic tests for syphilis
(STS), which consist of screening (reaginic) and confirmatory
(treponemal) tests, and dark field microscopy.
Reaginic tests use lipid antigens (cardiolipin from bovine hearts) to
detect reagin (human antibodies that bind to lipids). The Venereal
Disease Research Laboratory (VDRL) and rapid plasma reagin
(RPR) tests are sensitive, simple, and inexpensive reaginic tests that
are used for screening but are not specific for syphilis. Results may
be presented qualitatively (e.g., reactive, weakly reactive, borderline,
or nonreactive) and quantitatively as titers (e.g., positive at 1:16
dilution).
Many disorders other than treponemal infections (e.g., SLE,
antiphospholipid antibody syndromes) can produce a positive
(biologically false-positive) reagin test result. CSF
reaginic tests are reasonably sensitive for early disease but less so
for late neurosyphilis. CSF reagin tests can be used to diagnose
neurosyphilis or to monitor response to treatment by measuring
antibody titers.
Treponemal tests detect antitreponemal antibodies qualitatively
and are very specific for syphilis. They include the following:
Fluorescent treponemal antibody absorption (FTA-ABS) test
Microhemagglutination assay for antibodies to T. pallidum (MHA-TP)
T. pallidum hemagglutination assay (TPHA)