Syphilis Serology

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Syphilis Serology

• Michael Addidle

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Immigration medical on a 35 yr old Tongan
nationalwho is pregnant and has history of
rheumatoid arthritis.RPR ve titre 116TPPA
ve titre 1 1280

• A) Does this patient have syphilis?

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Treponema pallidum

• Spirochaete
• 4 sub-species
• Pallidum-syphilis
• Endemicun- bejel
• Pertenue- yaws
• Carateum- pinta
• Impossible to differentiate serologically

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Transmission of syphilis

• Sexual (including oro-genital and anogenital)
• Congenital
• Needlestick/blood transfusion

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There was a young man from Back Bay Who thought
syphilis just went away. He believed that a
chancre Was only a canker That healed in a week
and a day. But now he has "acne vulgaris -- (Or
whatever they call it in Paris) On his skin it
has spread From his feet to his head, And his
friends want to know where his hair is. There's
more to his terrible plight His pupils won't
close in the light His heart is cavorting, His
wife is aborting, And he squints through his
gun-barrel sight. Arthralgia cuts into his
slumber His aorta's in need of a plumber But
now he has tabes And saber-shinned babies While
of gummas he has quite a number. He's been
treated in every known way, But his spirochetes
grow day by day He's developed paresis Has
long talks with Jesus, And thinks he's the Queen
of the May
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Background

• Early non-treponemal serological tests developed
  1906 (Wassermann)
• Prevalence in big cities (Paris, New York) showed
  positive serology in 8-14 of the population.
• Treatment in the early 20th century usually
  involved either arsenic or mercury.
• Tuskegee study (1932-62)- trigger for
  establishing trial ethics

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Ways to diagnose syphilis

• Serology
• Dark field microscopy
• PCR
• Clinical
• Treponemes cannot be cultured in vitro

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Indications for testing.

• Screening attendees at antenatal clinics
• Screening attendees at SH clinics
• Screening donated blood samples
• Confirmation of positive screening tests
• Diagnostic testing in those with suggestive
  clinical features.
• Monitoring the therapeutic response

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How can we test for Syphilis?

• Non-Specific Treponemal Tests
• VDRL (lecithins)/RPR(cardiolipin)
• Good for monitoring Rx
• Specific Treponemal Tests.
• FTA (gold standard, subjective)
• TPPA/TPHA (very sensitive)
• Immunoblot (Innolia) (good but still early
  days)
• Treponemal IgM/IgG EIA (good commercial
  automated screening test)
• Treponemal IgM (detected very early)
• Stay positive therefore useless for diagnosing
  re-infection or response to therapy.

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How can we test for Syphilis?

• Traditionally screening was done with a
  non-treponemal test such as RPR or VDRL. Some
  smaller labs with low volumes still do this.
• Now vast majority of labs screen with a
  treponemal test and then confirm with a
  non-treponemal test. What problems might this
  lead to?

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How can we test for Syphilis?

• A common result now is Treponemal IgM/IgG
  positive by EIA and a negative VDRL.
• What scenarios can give rise to this result?
• Extra work and management dilemnas for Sexual
  Health consultants.

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Inno-Lia Immunoblot
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Timing of testing

• After appearance of lesion suggestive of primary
  syphilis, only negative serology at three months
  will exclude syphilis.
• However the majority of patients have positive
  serology at time of symptoms.
• Some patients presenting with early chancre will
  have both negative treponemal and non-treponemal
  serological tests.
• Once infected, treponemal serological tests will
  remain positive for life except occasionally in
  very early treated syphilis.

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Effect of Treatment on Testing

• VDRL and Treponemal specific IgM fall with
  treatment. However they may also become negative
  in chronic disease.
• Other Treponemal specific tests may decrease in
  titre but stay positive for the rest of the
  patients life. (except if disease treated really
  early)

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Pitfalls

• Screening not recommended with a non-treponemal
  test alone ie VDRL due to the potential for false
  negatives (usually early disease or prozone
  effect).
• False positives Can occur with both treponemal
  non specific tests and treponemal specific tests.
• If positive test results, repeat on same sample
  and on a repeat sample from the patient.
• HIV infection can play havoc with syphilis
  testing.

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The old demented patient with positive syphilis
serology

• Not that uncommon
• Look for documention of treatment for syphilis in
  the past.
• Seek advice from GUM specialist
• If VDRL positive need CSF
• Interpreting syphilis serology on CSF is complex.
  I go to textbooks/ask for peer assistance.

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PCR and syphilis

• PCR- being used a little for diagnosis of early
  syphilis with reasonable sensitivity and good
  specificity.
• May be of most use in busy STI clinics where
  there are a reasonable number of patients
  presenting with chancres. Dark field microscopy
  of little use in oral and anal lesions.
• Not much use for secondary/tertiary/latent
  syphilis.

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A new multiplex real-time PCR test for HSV1/2 and
syphilis an evaluation of its impact in the
laboratory and clinical setting

• Abstract
• Objectives To develop, evaluate and implement a
  new multiplex real-time PCR test for the
  detection of herpes simplex virus (HSV)1, HSV2
  and syphilis in a single sample using a single
  test.
• Methods A multiplex real-time PCR test detecting
  HSV1, HSV2 and Treponema pallidum was designed,
  validated and evaluated for a period of 6 months
  on patients attending the Sandyford Initiative (a
  series of genitourinary medicine clinics in and
  around Glasgow). A total of 692 samples were
  tested, and T pallidum PCR positives were
  confirmed by a second PCR at the Scottish
  Reference Laboratory (SBSTIRL). All PCR results
  were aligned with dark ground microscopy findings
  and serological results where available and
  compared.
• Results The laboratory validation of the
  multiplex assay showed the test to be sensitive,
  specific and robust. Of the 692 samples, 139 were
  positive for HSV1, 136 for HSV2, 15 for syphilis,
  one for both syphilis and HSV1, and 401 were
  negative the reference laboratory confirmed all
  T pallidum PCR-positive samples. The PCR test was
  more sensitive than both dark ground microscopy
  and serological testing for the diagnosis of
  primary syphilis.
• Conclusions The introduction of this new test has
  led to a better turnaround time for the diagnosis
  of genital ulcer disease, better detection of
  primary syphilis infection, and the detection of
  unexpected cases of syphilis where the
  aetiological agent suspected was HSV.

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Follow-up

• Immigration medical on a 35 yr old Tongan
  nationalwho is pregnant and has history of
  rheumatoid arthritis.
• Treated for syphilis. 2 years post treatment,
  re-tested. Results are nowRPR ve titre 14
• TPPA ve titre 1 1280
• What are the possible scenarios?

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Take Home Messages

• Be aware of different serological tests for
  syphilis and the difference between treponemal
  and non-treponemal tests.
• Note that screening low prevalence populations
  increases chances of false positives.