Compiled by Simon Wright NUM Sydney
Sexual Health Centre
The basic test for syphilis is an Elisa Antibody test
which detects antibodies to syphilis. This is a very
sensitive test
Negative Elisa will indicate that the person has not
been infected with syphilis up until three months ago
(there is a window period similar to HIV window period)
The presence of positive Elisa antibodies indicate that the
patient has been infected with Syphilis
The lab will automatically test all new positive Elisa
antibody tests and TPPA, FTa antibody, and RPR test
will be done
Elisa Ab
TPPA
FTa Ab
RPR
Positive
Positive
Positive
Negative
Elisa Ab
TPPA
FTa Ab
RPR
Positive
Positive
Positive
Positive
Elisa Ab
TPPA
FTa Ab
RPR
Positive
Negative
Negative
Negative
Elisa Ab
TPPA
FTa Ab
RPR
Positive
Positive
Positive
Negative
An old infection that has been treated (proven record
of treatment from notes or patient history)
In the absence of any history of previous treatment or
negative syphilis serology in the past two years a
diagnosis of Late Latent Syphilis is made
If there is a proven history of negative syphilis
serology in the past 2 years a diagnosis of
early latent syphilis is made
Late Latent syphilis is treated currently with 3
shots of antibiotics over 3 weeks and no further
follow-up is needed as the RPR is already
negative
As Syphilis infection is only infectious for the first 6
months, PN should go back as far as possible to
ensure as many partners are aware and screened
This will include all current partners who are long-term
partners.
A diagnosis of early latent syphilis can only be made
with a Negative RPR and history of negative syphilis
serology within the past two years.
This will be treated with one shot of antibiotics
and again if RPR is negative, no further
follow-up is needed as the RPR is already
negative
PN should go back two years to ensure as
many sexual partners are informed and are
screened.
There must be proven history of treatment for past
syphilis infection.
WARNING
Re-infection of syphilis can not be ruled out unless regular
Syphilis serology tests are done as re-infection will cause the
RPR to become positive again with high titres but with time
the titres will drop and RPR may go negative again even
without further treatment.
In a very sexually active person with many sexual partners
and no history of resent negative syphilis serology, reinfection must be considered and such cases discussed with
senior doctor
Gay men and commercial sex workers are at risk of reinfection
Syphilis Antibody
TPPA
RPR
FTa Ab
Positive
Positive
Positive (with titres)
Positive
These may be negative
in a primary syphilis
This would indicate resent infection of Syphilis especially if
the RPR titres are high i.e. 1:38
The presents of any symptoms will determine the stage of
infection:
Ulcer or chancre present would possibly
indicate Primary infection of Syphilis
Presents of rash on trunk, hands or soles of
feet might indicate secondary syphilis
infection
Primary Syphilis Infection
Treated with one shot of antibiotics.
PN would need to go back 3 months to
ensure all sexual partners are advised to be
screened.
Patient should be reviewed by the doctor two
weeks post treatment and further blood test
done at one month and repeated monthly
until sero-fast or Negative RPR
Sero-Fast means that the RPR has not changed or
increased over a three month period indicating that
treatment has been successful
What is the significance of an RPR that
remains positive?
If the RPR remains Positive (neat) this is as good as
negative
What are the titres and what are their
significance?
In the case of the RPR test for syphilis, the sample is tested neat
(undiluted) if that is positive it is then diluted with a diluents of the same
volume and if that is still positive it is said to be positive 1:2.
That sample is then diluted again and if remains positive it is said to be
positive 1:4 and so on so could be 1:8, 1:16, 1:32 and so on
If 1:32 is still positive and it is diluted again and this time is negative, the
result will be 1:32 (as 1:64 would mean the sample is too diluted to pick up
and give a positive result
It could be argued that a an RPR that is positive neat is the same as
negative as one dilution is enough to produce a negative result.
EXIT
In the case of Syphilis, the titres that are expressed with the RPR result
indicates the strength of the positive result. The blood is tested neat, if that
is positive, it is diluted with a diluents of the same volume and retested, if
that diluted sample is also neat, the result will be expressed as 1:2, That
sample will then be diluted again and retested and if positive will be
expressed as 1:4 and so on.
Each time the sample is diluted again and remains positive it is expressed
as 1:8, 1:16, 1:32 until the sample is diluted enough to not produce a
positive result. So if at 1:32 is positive and at further dilution of 1:64 was
negative, the result will be 1:32 as 1:64 was too diluted to give a positive
result.
If the sample is positive neat and with one dilution 1:2 is negative
this indicates a very weak positive and could argued to be the
same as negative,
What are the tests for Syphilis?
•
Syphilis Antibody Elisa Assay
•
TPPA Treponema Palladium Particle Agglutination
•
(TPHA) Treponema Pallidum Haemagglutination Assay (no longer in use)
•
RPR Rapid Plasma Regain (often expressed as titres)
•
FTA Ab Fluorescent Treponemal Antibody Absorption Test
TPPA & FTA Ab in the vast majority of patients infected and treated for Syphilis will
remain positive for life, but a very small number of patients may lose these positive
markers
The Elisa Antibody test is very sensitive and will nearly always remain positive for
life
Primary Syphilis Signs & Symptom
1.
Chancre, usually a solitary, painless, clean ulcer with an indurated base.
2.
Regional lymphadenopathy, discrete, painless, rubbery
Diagnosis
1.
Dark ground microscopy x 3 to identify Trepnema pallidum spirochaetes
2.
Serological tests for syphilis (STS). May be negative at this stage
Treatment & Management
1.
Benzathine penicillin 2.4 MU IM - single dose
2.
Doxycycline P.O. 100 mg bd for 14 days (contraindicated in pregnancy)
Procaine penicillin IM 600,000 units daily for 10 days
3.
Complications of treatment
1.
Painful injection
2.
Jarisch-Herxheimer reaction. Warn patients; advise bed rest, paracetamol or aspirin
or ibuprofen. This is caused by toxins released from dead spirochetes causing an
immune response and high fever and malaise
Secondary Syphilis, Signs & Symptoms
1.
2.
3.
4.
Skin lesions, non-itchy macular papular rash, may involve palms and soles of
feet. Pink or copper coloured condylomata in moist areas. Pustular lesions and
patchy alopecia.
Mucous membrane lesions, painless erosions on genitals or in mouth
Generalised lymphadenopathy
Fever , malaise, arthralgia
Diagnosis
1.
Dark ground microscopy from mucous patches
2.
Syphilis serology, all tests likely to be positive
Treatment & Management
1.
1 shot of antibiotics
2.
All patients to see HA for PN going back 3-4 months
3.
Review by doctor 2 weeks post treatment
4.
Monthly blood test to ensure successful treatment until RPR is negative or serofast
Classic symptoms of Secondary Syphilis
Classic symptoms of Secondary Syphilis
Some classic chancres seen in primary syphilis
Spirochetes as seen at dark ground microscopy
Syphilis Antibody
TPPA
RPR
FTa Ab
Positive
Positive
Negative
Positive
The above serology result could indicate the following:
1. A past treated infection (documentation of past treatment should be made)
2. An old infection that has not been treated (no past history of syphilis treatment) This
will be diagnosed as either Early Latent or Late Latent Syphilis
*
It is important to remember that if a patient has been treated for syphilis many years ago but has
not had regular Syphilis serology done, it is possible that the patient may have been re-infected
at some time and possibly gone undiagnosed and the RPR has returned to negative over the
passage of time. This is particularly worth thinking about in a patient who is very sexually active
(Gay men are more at risk of syphilis infection)
How is a diagnosis of Early or late latent syphilis made?
Early or Late
Latent Syphilis?
•
In the absence of any symptoms such as Chancre or Rash indicating primary or
secondary Syphilis and serology consistent with infection being present for some time
i.e. Negative RPR (or positive with titre of neat), a diagnosis or early latent or late
latent has to be made.
•
For a diagnosis of Early Latent Syphilis to be made, there must be proven
negative serology within the past 2 years. If the patient was negative 2 or less years
ago, then we know that this infection was acquired since the last negative serology.
•
Late Latent Syphilis will be made if there is no proven negative serology within the
past 2 years. This means that it is very difficult to pinpoint when the infection was
acquired and therefore how long the patient has been infected.
Syphilis Antibody
TPPA
RPR
FTa Ab
Positive
Negative
Negative
Negative
The above serology could mean one of the following:
1.
A false biological positive. This test must be repeated and blood may be sent to
the reference laboratory for definitive diagnosis. (The serology lab will make the
decision about sending specimens to the reference lab).
2.
In some cases, a person who has had Syphilis in the past, may lose their positive
TPPA and Fta Ab, it is unusual but not impossible. It is for this reason these results
must be checked and followed up carefully. The Antibody test is very sensitive and
is more reliable than TPPA and Fta Ab.
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