Interesting Syphilis Serology



  • 66 year old MSM
  • HIV CDC II, stable on HAART, CD4 ~700, VL undetectable.
  • Previous history of treated syphilis
  • Has 3-monthly STI screening at SOPV
  • In September 2006, STS showed usual stable results:

  • At his next screening, RPR was 32!

  • Assessed as having early asymptomatic syphilis
  • Had a single dose of benzathine penicillin on 12/12/2006
  • This was followed by an intense Herxheimer reaction


What happened next

  • His first follow-up RPR, 6 weeks after treatment, was 128!!

  • There was no risk of reinfection.
  • What would you have done?

Have a think, then .......



What was done:


  • Treatment failure was thought to be unlikely:
  • early diagnosis
  • recommended penicillin treatment was given
  • Herxheimer reaction
  • well-maintained CD4 count, despite HIV infection
  • What was thought more likely was that, because of the delay of 13 days between diagnosis and treatment, we had missed the peak of his RPR, and that the first follow-up level of 128 probably closely represented the peak.
  • However, the patient asked for re-treatment with 3 doses of benzathine penicillin, which were duly given.
  • His subsequent serology showed a satisfactory fall in RPR:

  • In mid-May, RPR via his GP was 4.


The lesson:

  • In cases of early syphilis, when the RPR may still be rising, we must do a baseline RPR at the time of treatment.

Dated November, 2007