2. T pallidum cannot be cultivated in vitro and is too small to be seen
under the light microscope. Serologic testing is considered the
standard method of detection for all stages of syphilis.
The traditional approach has been to first perform non-
treponemal serology screening using the Venereal Disease
Research Laboratory (VDRL), Rapid Plasma Reagin (RPR) or the
recently developed ICE Syphilis recombinant antigen test.
Sensitivity of the VDRL and RPR tests are estimated to be 78-
86% for detecting primary syphilis, 100% for detecting
secondary syphilis, and 95-98% for detecting tertiary syphilis.
Specificity ranges may be reduced in individuals who have
coexisting conditions (ie, collagen vascular disease,
pregnancy, intravenous drug use, advanced malignancy,
tuberculosis, malaria, viral and rickettsial diseases)
3. Results turn positive 1-2 weeks after chancre formation.
Non-treponemal tests usually become nonreactive with
time after treatment. Serology values in patients with HIV
infection may take longer to fall. Some non-treponemal
antibodies can persist, sometimes for life, a conditioned
referred to as ”serofast.”
Because of the possibility of false-positive results,
confirmation for any positive or equivocal non-
treponemal test result should follow with a treponemal
test -Fluorescent Treponemal Antibody-ABSorption (FTA-
ABS), Micro Hemagglutination Assay T pallidum (MHA-
TP), T pallidum Hemagglutination (TPHA), and T
pallidum particle agglutination (TPPA) tests. Treponemal
enzyme immunoassay (EIA) for IgG and IgM.
4. Blood is drawn from a vein (venipuncture), usually from the
inside of the elbow or the back of the hand.
The Wassermann test or Wassermann reaction is an antibody test for syphilis,
named after the bacteriologist August Paul von Wassermann, based on
complement fixation. It was the first blood test for syphilis and the first in the
nontreponemal test category.
5.
6. Doctors also routinely screen pregnant women for syphilis
using an RPR test.
States used to require that people who are applying for a
marriage certificate get a screening test for syphilis.
Doctors obtain blood for the RPR test with a simple procedure
called a venipuncture.
This is very similar to VDRL and has the same disadvantages.
7. FTA-ABS is commonly used as a confirmatory test. It has a
sensitivity of 84% for detecting primary syphilis infection and
almost 100% sensitivity for detecting syphilis infection in other
stages. Its specificity is 96%. [18]
Some labs have adopted reverse sequence screening in order
to reduce time, labor, and costs. Reverse screening test sera
first by automatable treponemal enzyme and
chemiluminescence immunoassays (EIA/CIA), followed by
testing of reactive sera with a non-treponemal test.
8.
9. Dark field microscopy is a possible mode of evaluating moist
cutaneous lesions, such as the chancre of primary syphilis or
the condyloma lata of secondary syphilis.
If darkfield microscopy is not available, direct fluorescent
antibody T pallidum [DFA-TP].
Both procedures detect at a rate of approximately 85-92%.
Slit-lamp examination and ophthalmic assessment can be
used to differentiate between acquired and congenital syphilis
(presence of interstitial keratitis) in patients with latent
infection of uncertain duration.
10.
11. CSF laboratory abnormalities are common in persons with
early syphilis, even when clinical neurological findings are
absent. If clinical evidence of neurological involvement is
found, a CSF examination should be performed.
There is no single test available for the definitive diagnosis of
neurosyphilis; rather, the clinical symptoms, serology, and CSF
values (CSF cell count or protein and a reactive CSF-VDRL)
must be used.
CSF abnormalities include elevated
protein levels and pleocytosis, which are
found in up to 70% of patients.
12. Treponemal tests (ie, TPPA, FTA-ABS, EIA, CIA) using neonatal
serum are not recommended owing to passive transfer of IgG
antibodies, which react with the reagents in these tests. All
infants born to mothers with syphilis should be evaluated with
a quantitative nontreponemal serologic test (RPR or VDRL)
performed using the neonate’s serum.
