Background Understanding the risk factors for HIV acquisition allows targeted interventions to reduce HIV transmission such as PrEP.

Aims/Objectives To evaluate HIV incidence in HIV-negative MSM with early syphilis infection.

Methods A retrospective case-note review of MSM who were diagnosed with early syphilis between January and June 2014 at a London sexual health clinic.

Results 206 MSM were diagnosed with early syphilis: 110 HIV-negative; 96 HIV-positive. For 110 HIV-negative MSM, median age was 32 y, median number of sexual partners in last 3 months was 4. Reported drug use in the previous month was 38%; 19% had injected drugs. Syphilis stage was primary (31%), secondary (25%), early latent (45%).Up to February 2016, total follow-up was 144 person-years. 12 (11%) were newly diagnosed HIV-positive. HIV incidence was 8.3 (95% confidence interval, CI 4.2–14) per 100 person-years follow-up (HPYFU). Incidence of rectal STIs was: rectal chlamydia, 27 HPYFU (CI 19–36); rectal gonorrhoea, 33 HPYFU (CI 25–44); syphilis re-infection, 10 HPYFU (CI 5.7–17).

Conclusions The significant risk of HIV seroconversion following a diagnosis of early syphilis suggests that this group may particularly benefit from the use of pre-exposure prophylaxis. The high levels of subsequent rectal infections support the inclusion of regular STI screening in PrEP management guidelines.