Facing increased sexually transmitted infection incidence in HIV preexposure prophylaxis cohorts: what are the underlying determinants and what can be done?

Abstract

The combined incidence of chlamydia, gonorrhoea and syphilis in MSM PrEP (preexposure prophylaxis) cohorts now frequently exceeds 100 per 100 person years. The efficacy of antiretroviral PrEP in reducing HIV transmission has led to efforts to find similar biomedical ways reduce sexually transmitted infection (STI) incidence. We review the recent evidence for these and other strategies. Doxycycline PrEP/postexposure prophylaxis has been shown to reduce the incidence of syphilis and chlamydia but not gonorrhoea. A meningococcal vaccine has been found to result in a lower incidence of gonorrhoea. Novel insights into the role of the pharynx in the transmission of gonorrhoea have led to clinical trials of oral antiseptics to reduce the spread of gonorrhoea. Intensified STI screening has been introduced in a number of clinics. Serious concerns have however been raised about the emergence of resistance to each of these strategies. This is particularly true for doxycycline PrEP which is not advocated by any guidelines we reviewed. Randomized controlled trials are urgently required to ascertain the benefits and risks of interventions to reduce STIs in MSM PrEP cohorts.