Introduction There has been a significant increase in infectious syphilis in men who have sex with men (MSM) since 2000. We have been using a local Tp-PCR in conjunction with dark ground microscopy and serology in patients with genital ulcer disease to increase the sensitivity of primary syphilis diagnosis. The aim of this project was to evaluate the increased diagnostic yield that Tp-PCR offers our service.

Methods We reviewed the microbiology (syphilis serology and Tp-PCR) of patients coded as primary syphilis between December 2015 and December 2016. We also collected demographic data on these cases.

Results 74 patients were accurately coded as having primary syphilis all of whom were MSM (24/74(32%)) HIV positive). STS was requested in 73 patients and 69/73(94.5%) tested positive. Tp-PCR was requested in 41 patients and 35/41(85.4%) tested positive. DGM was performed in 13 patients and 5/13(38.5%) tested positive. Both STS and Tp-PCR were requested in 40 patients: 30/40(75%) tested positive for both, 6/40(15%) tested positive only for STS and 4/40(10%) tested positive only for Tp-PCR (one had PCR which was negative). One patient had positive Tp-PCR but no STS result available.

Discussion During a 12 month period 74 patients were diagnosed with primary syphilis. 40 had combined STS and Tp-PCR – within this cohort 10% (4/40) had confirmed primary syphilis due to Tp-PCR as STS was negative and DGM was either negative or not tested. The addition of Tp-PCR provided an opportunity for early confirmation of syphilis.