Treponema pallidum PCR screening at mucosal sites of asymptomatic men who have sex with men taking HIV pre-exposure prophylaxis.

With the ongoing syphilis epidemic in men who have sex with men (MSM), we investigated the role of using Treponema pallidum polymerase chain reaction (PCR) testing at the oral cavity and anus in MSM taking pre-exposure prophylaxis for the early detection of syphilis. We evaluated whether the PCR tests from these mucosal sites can detect syphilis infection early, before the development of syphilis antibodies in serology. Our study found two syphilis cases among 309 MSM, and only one syphilis case had a positive anal PCR swab, although serology was positive. We conclude that additional PCR testing is likely to be expensive and would not be cost effective for individuals who regularly screen for syphilis. However, future studies with a larger sample size are required.