O08.5 Impact of increased asymptomatic testing for gonorrhoea among MSM on PrEP on the transmission and development of antimicrobial resistance

Background In many countries, men who have sex with men (MSM) using pre-exposure prophylaxis (PrEP) are routinely three-monthly tested and treated for Neisseria gonorrhoeae (gonorrhoea), which might increase antimicrobial resistance (AMR). However, there is uncertainty about how AMR emerges. We investigated the impact of frequent testing and treating on gonorrhoea prevalence and AMR assuming different ways of AMR emergence. Methods We developed a compartmental model, which included three sexual activity classes that differed in unprotected sex partner numbers and testing uptake. AMR to ceftriaxone was incorporated as stepwise increases in minimum inhibitory concentrations and eventual resistance (MIC drift) in three separate ways: direct selection pressure through ceftriaxone treatment; indirect selection pressure through antimicrobials treatment for other reasons; or imported infection. Each model was calibrated to the ceftriaxone MIC curve from the Dutch Gonococcal Resistance to Antimicrobials Surveillance program (2015–2019). We estimated the impact of three-monthly testing of high-risk MSM on overall and AMR prevalence in 2030. Results Overall gonorrhoea model prevalence was 3.4% (95% uncertainty interval 3.2%–3.5%), and 14.3% (11.7%–18.0%) in high-risk MSM. Three-monthly testing resulted in 66%–93% reductions in overall prevalence for all three ways in which AMR development was modelled. AMR prevalence was low in 2030 for all three mechanisms, but increased fastest with direct selection compared to indirect or imported. With direct selection, AMR prevalence was 1.7 (1.3–2.0) times higher than with indirect selection and 8.2 (2.7–16.1) times higher than through imported infection. When high-risk MSM increased numbers of unprotected sex partners, three-monthly testing reduced overall prevalence less and AMR prevalence increased, especially with direct selection. Conclusion With frequent testing of MSM, direct selection pressure through treatment leads to more gonococcal resistance than indirect selection or imported infection. This study highlights the need to increase our understanding of mechanisms of AMR emergence in N. gonorrhoeae.