Treponemal Tests for Syphilis Immunology Review 398
Detects
Reagent(s)
Positive reaction
Specimen(s)
Reactivity during
disease
ANTIBODY CAPTURE ENZYME-
LINKED IMMUNOSORBENT
ASSAY (ELISA)
Antibody to T. pallidum.
Enzyme-labeled treponemal ag.
Color development following addition
of substrate.
Serum
High sensitivity in primary syphilis.
Decreases in later stages.
FLUORESCENT TREPONEMAL
ANTIBODY ABSORPTION
(FTA-ABS)
Antibody to T. pallidum
Sorbent (nonpathogenic tre-
ponemes—Reiter strain),
slides with Nichols strain of T.
pallidum, fluorescein-labeled
antihuman globulin
Fluorescence
Serum, CSF
Usually pos before reagin tests.
Some false negs in primary
syphilis. Usually pos for life
TREPONEMA PALLIDUM
PARTICLE AGGLUTINATION
(TP-PA)
Antibody to T. pallidum
Colored gelatin particles
coated with treponemal ag
Agglutination of sensitized
gel particles. Smooth mat
over surface of well
Serum
Not as sensitive in primary
syphilis as FTA. Sensitivity
close to 100% in secondary
syphilis. Usually pos in late
stages
continued...
