NOTE: It is not possible to distinguish a failure to respond to therapy from reinfection using serology.
Patient selection: monitoring after adequate therapy for syphilis
ratio for decreasing serologic response =
= (denominator of RPR titer before therapy) / (denominator of RPR titer after therapy)
ratio for increasing serologic response =
= (denominator of RPR titer after therapy) / (denominator of RPR titer before therapy)
Criteria for an inadequate response to therapy (or reinfection) - one of the following:
(1) lack of a 4-fold or greater decrease in the RPR titer
(1a) >= 6 months after primary or secondary syphilis
(1b) >= 12 months after therapy for latent syphilis
(1c) >= 24 months after therapy for neurosyphilis
(2) presence of a 4-fold or greater increase in the RPR titer >= 30 days after therapy
(3) signs or symptoms of syphilis that persist or recur
