Relapse of secondary syphilis after benzathine penicillin G - Molecular analysis

Background and Objectives: It is difficult to distinguish between relapse and reinfection in patients who develop a second episode of syphilis after treatment. Goal: The goal of this study was to use molecular methods to distinguish between relapse and reinfection in a patient with recurrent secondary syphilis. Study Design: Treponema pallidum tprK sequences were amplified from cerebrospinal fluid (CSF), skin, and blood from the initial presentation and from blood from the second presentation. Neighbor-joining clustering analysis was performed for deduced tprK sequences from the case patient and for sequences derived from blood and CSF of a different patient with secondary syphilis. Results: The case patient's tprK sequences from both episodes of syphilis clustered together with a high degree of similarity. Conclusion: Our patient likely relapsed despite treatment.