Relapse of secondary syphilis after benzathine penicillin G: molecular analysis

Sex Transm Dis. 2004 Mar;31(3):196-9. doi: 10.1097/01.olq.0000114941.37942.4c.


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.

Publication types

  • Case Reports
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Anti-Bacterial Agents / therapeutic use*
  • Bacterial Proteins*
  • HIV Infections / complications
  • Humans
  • Male
  • Penicillin G Benzathine / therapeutic use*
  • Porins / genetics
  • Recurrence
  • Serotyping
  • Syphilis / cerebrospinal fluid
  • Syphilis / complications
  • Syphilis / drug therapy*
  • Treatment Failure
  • Treponema pallidum / classification


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Porins
  • major outer sheath protein, Treponema
  • Penicillin G Benzathine