Prevalence of Neisseria meningitidis carriage among men who have sex with men at a sexual health clinic in Brussels, Belgium: a cross-sectional study

To assess the prevalence of Neisseria meningitidis (Nm) carriage among men who have sex with men (MSM) and examine potential risk factors associated with colonization. This was an observational, cross-sectional, monocentric study. Inclusion criteria were asymptomatic adult MSM. Recruitment took place at an outpatient sexual health clinic in Brussels, Belgium from October 2019 to March 2020. The primary outcome of this study was to determine the prevalence of meningococcal oropharyngeal carriage. Secondary outcomes included characterization of the participants colonized with Nm and serogroup identification of encapsulated strains. Ordinal logistic regression analysis was performed to evaluate for associations with Nm colonization. A total of 143 participants were included, of which 36 (25.2%) were found to be colonized with Nm. The most common encapsulated strain identified was serogroup B (50%). Colonized individuals had a median (IQR) age of 36.5 (29-43) years, 69.4% were Caucasian, and 38.9% indicated having 2 to 5 kissing-only partners while 47.2% reported having no sex partners during that same period. Multivariable analysis showed that not having been vaccinated against Nm in the past 5 years was the only characteristic significantly associated with being colonized with Nm (odds ratio 3.38; 95% confidence interval 1.26-6.58, p = 0.02). In this analysis of MSM, asymptomatic Nm carriage was observed to be 25.2% and serogroup B (50%) was the most frequently identified. Non-vaccination against Nm was the only factor significantly associated with colonization. Further research is needed to better understand Nm colonization in this population.