27-28th Page Flashcards
(88 cards)
What do treponemal tests detect?
Detect antibodies directed against the T. pallidum organism or against specific treponemal antigens.
Are treponemal tests easy to perform?
No, treponemal tests are more difficult to perform and time-consuming.
What type of antibodies are predominantly found in early or untreated early latent syphilis?
predominantly IgM antibodies.
What follows the early immune response to T. pallidum infection?
ppearance of IgG antibodies, which soon become predominant.
When is the greatest elevation in IgG concentration seen?
in secondary syphilis.
What is the Treponema Pallidum Immobilization Test (TPI)?
The TPI uses patient serum with live, actively motile T. pallidum extracted from testicular chancre of rabbit and complement.
positive TPI
Positive: >50% of treponemes are immobilized.
negative TPI
Negative: If fewer than 20% are immobilized.
doubtful TPI
Doubtful: Ranges 20 - 50% are immobilized.
What is the principle of the Fluorescent Treponemal Antibody Absorption Test (FTA-ABS)?
FId
indirect immunofluorescence
What is nonpathogenic treponemes in FTA-ABS
Reiter
What happens to the patient serum in the FTA-ABS test?
The patient serum is heat-inactivated and treated with a sorbent to remove cross-reactivity with treponemes other than T. pallidum.
How is the intensity of fluorescence reported in the FTA-ABS test?
green color is reported on a scale of 0 to 4.
reactive FTA-ABS
Reactive: 2+ to 4+.
negative FTA-ABS
Negative: No fluorescence.
FTA-ABS test is minimally reactive
If minimally reactive (1+), the test must be repeated with a second specimen drawn in 1 to 2 weeks.
what strain of T.pallidum is fixed to slides that is used for the test?
Nichol
TPHA test (TPHA (T. pallidum hemagglutination assay)
uses tanned sheep RBCs coated with antigen from the Nichols strain.
TAPA test? TAPA (T. pallidum particle agglutination assay)
uses gel particles sensitized with T. pallidum sonicate.
MHA-TP (micro hemagglutination assay for T. pallidum)
using formalinized, tanned sheep RBCs sensitized with antigen from the Nichols strain.
performed using microtiter plates
HATTS (Hemagglutination Treponemal test for Syphilis)
using glutaraldehyde stabilized turkey RBC.
What is the MONOSPOT TEST?
A rapid differential slide test that uses horse RBCs as an indicator.
More sensitive compared to the Davidson differential test.
positive result in the MONOSPOT TEST?
Dark clumps against a blue-green background, distributed uniformly throughout the test circle.
negative result in the MONOSPOT TEST?
No agglutination but may have fine granularity against a brown-tan background.