Interpretation of Results of Serologic Reaction Test for Syphilis
STS
TP antigen
Interpretation of results
RPR〔LA〕, etc.
TP antibody〔LA〕, etc.
(-)
(-)
Non-syphilis Very early syphilis (rare)
(+)
(-)
Very early syphilis (rare)*
Biological false positive (BFP)
(+)
(+)
Active syphilis (requires treatment)
Syphilis in a cured state
(-)
(+)
Syphilis in a cured state
Very early stage syphilis
False positive due to nonspecific reaction of the TP antigen system (rare)
* The investigation regarding the presence of any diseases that present with
BFP or recent opportunities for infection should be performed.
The progression of STS antibody titers should be monitored,
and if a positive reaction to TP antibodies is observed,
early syphilis infection is suspected.
Clinical diagnosis is always prioritized, and serological tests are only auxiliary diagnostics.
[Use and Notes of Serologic Reaction Test for Syphilis]
<STS>
The antibody against cardiolipin antigen. It becomes positive in the early stages of
syphilis infection and often becomes negative after treatment and reflects syphilis symptoms.
It often causes biological false positive reaction (BFP).
<Biological false positive (BFP)>
STS (RPR) has a high rate of biological false positives (BFP),
and in addition to syphilis infection,
false positives can also be seen in liver disease, autoimmune disease,
and in pregnant women.
<TP antibody>
The antibody against treponema antigen which
is the specific antibody observed during syphilis infection.
In the serum of patients who have previously tested positive for syphilis,
antibody titers may remain high for an extended period of time.
Nonspecific reaction is observed in rare cases.
