Sorted By Test Name - Mayo Medical Laboratories

SYPHG
81814
point in the past, but does not distinguish between treated and untreated infections. This is because
treponemal tests (eg, EIA, multiplex flow immunoassay, or fluorescent treponemal antibody-absorbed)
may remain reactive for life, even following adequate therapy. Therefore, the results of a nontreponemal
assay, such as rapid plasma reagin, are needed to provide information on a patient's disease state and
history of therapy.
Reference Values:
Negative
Clinical References: Tramont EC: Treponema pallidum (Syphilis). In Principles and Practice of
Infectious Diseases. 5th edition. Edited by GL Mandell, JE Bennet, R Dolin. New York, Churchill
Livingstone, 2000, pp 2474-2491
Syphilis IgG Antibody with Reflex RPR, Serum
Clinical Information: Syphilis is a disease caused by infection with the spirochete Treponema
pallidum. The infection is systemic and the disease is characterized by periods of latency. These features,
together with the fact that Treponema pallidum cannot be isolated in culture, mean that serologic
techniques play a major role in the diagnosis and follow-up of treatment for syphilis. Historically, the
serologic testing algorithm for syphilis included an initial nontreponemal screening test, such as the rapid
plasma reagin (RPR) or the venereal disease research laboratory (VDRL) tests. Because these tests
measure the host's antibody response to nontreponemal antigens, they lack specificity. Therefore, a
positive result by RPR or VDRL requires confirmation by a treponemal-specific test, such as the
fluorescent treponemal antibody-absorbed (FTA-ABS) or microhemagglutination assay (MHA-TP).
Although the FTA-ABS and MHA-TP are technically simple to perform, they are labor intensive and
require subjective interpretation by testing personnel. Recently, EIA and multiplex flow immunoassays
(MFI) were introduced to assess serologic response to Treponema pallidum. The Bio-Rad BioPlex
Syphilis IgG assay is an example of MFI technology, which utilizes specific, treponemal antigens coated
on microspheres for the detection of IgG-class antibodies to Treponema pallidum. The BioPlex Syphilis
IgG assay is highly sensitive and specific (see Supportive Data), and allows for an objective interpretation
of results. Due to several factors including the low prevalence of syphilis in the United States, the
increased specificity of treponemal assays, and the objective interpretation of MFI and EIA technology,
initial serologic testing by a treponemal-specific assay (eg, EIA or MFI) is now commonly performed in
clinical laboratories. Specimens testing positive by the treponemal-specific assay are then tested by RPR
to provide supplementary serologic data, as well as to provide an indication of the patient's disease state
and history of treatment. During early primary syphilis, the first antibodies to appear are of the IgM-class,
with IgG-class antibodies reaching significant titers later in the primary phase. As the disease progresses
into the secondary phase, IgG-class antibodies to Treponema pallidum reach peak titers, and may persist
indefinitely regardless of the disease state or prior therapy. For prenatal syphilis screening, the IgG test is
recommended. IgM testing should not be performed during routine pregnancy screening unless clinically
indicated. Treponema pallidum IgG antibodies persist indefinitely, regardless of the course of the disease.
If treatment of an original Treponema pallidum infection was not monitored, a diagnosis of reinfection
may actually represent either a resurgence of an inadequately treated earlier infection or persistent IgG
antibodies from a resolved infection.
Useful For: An aid in the diagnosis of active Treponema pallidum infection Routine prenatal screening
Interpretation: A positive IgG treponemal test suggests infection with Treponema pallidum at some
point in the past, but does not distinguish between treated and untreated infections. This is because
treponemal tests (eg, EIA, multiplex flow immunoassays, or fluorescent treponemal antibody-absorbed
[FTA-ABS]) may remain reactive for life, even following adequate therapy. Therefore, the results of a
nontreponemal assay, such as rapid plasma reagin (RPR), are needed to provide information on a
patientâ€s disease state and history of therapy. Interpretation of results for syphilis IgG and RPR:
-IgG-positive and RPR-positive: Untreated syphilis unless ruled out by treatment history. Patients who
have been treated in the past may be considered to have new syphilis infection if RPR titers show 4-fold,
or greater, increase between acute- and convalescent-phase specimens. -IgG-positive and RPR-negative:
Past, successfully treated syphilis in patients with history of appropriate therapy. In those patients without
a history of treatment, a second treponemal assay (eg, FTA-ABS) should be performed to determine if the
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