Background:
Men-who-have-sex-with-men (MSM) experience high rates of Neisseria meningitidis (Nm) carriage, bacterial sexually transmitted infections (STIs), and antimicrobial exposure, creating conditions for the emergence and spread of antimicrobial resistance (AMR). A 2023 cross-sectional study in the UK (MSM CARR-1) found oropharyngeal Nm carriage among MSM was 21.3% with tetracycline resistance in 43% of isolates, and genitourinary (GU)-associated Nm lineages, including ST-5662 [1]. In 2025, doxycycline post-exposure prophylaxis (doxyPEP) and 4CMenB vaccination were introduced in the UK targeting MSM, but the impact of these novel STI prevention interventions on meningococci is unknown.
Methods:
The MSM CARR programme comprises carriage studies in MSM attending a London sexual health clinic. MSM CARR-1 established pre-doxyPEP/4CMenB baseline epidemiology, genomics, and AMR. MSM CARR-2 is an ongoing study assessing Neisseria carriage, AMR, and intervention uptake. Genomic analyses of all available Nm isolates in PubMLST belonging to the ST-5662 lineage (n=157, accessed April 2026) were performed to characterise AMR determinants and predict 4CMenB vaccine coverage.
Results:
Genomic analyses of the ST-5662 lineage (n=157) identified a sub-lineage with widespread tetracycline resistance and limited predicted coverage by 4CMenB, suggesting this lineage may be sensitive to both antimicrobial and vaccine-driven selection pressures.
Preliminary MSM CARR-2 data (n=52 at the time of writing, April 2026) indicate high uptake of interventions: 30/52 (57.7%) participants reported doxyPEP use, 31/52 (59.6%) reported 4CMenB vaccination, and 21/52 (40.4%) reported both, demonstrating exposure of meningococci to these interventions.
Conclusions:
MSM-associated meningococci exhibited high baseline AMR before intervention rollout, with the ST-5662 lineage representing a GU-associated MenB population of particular concern. Early during-implementation data show high-uptake of doxyPEP and 4CMenB, creating conditions for potential selection of both resistance and vaccine antigen profiles. Ongoing genomic surveillance through MSM CARR-2 will be critical to determine the impact of these interventions on meningococcal population structure and AMR dynamics.