Antimicrobial Susceptibility of Commensal Neisseria in the General Population and Men Who Have Sex with Men in Belgium: A Cross Sectional Survey

Abstract

Background: Non-pathogenic Neisseria are a reservoir of antimicrobial resistance genes for pathogenic Neisseria meningitidis and Neisseria gonorrhoeae. Men who have sex with men (MSM) are at risk of colonization/infection with resistant non-pathogenic and pathogenic Neisseria. We assessed if the antimicrobial susceptibility of non-pathogenic Neisseria among MSM differs from the general population and if antimicrobial exposure impacts susceptibility. Methods: We recruited 96 participants at a sexually transmitted infections clinic in Antwerp, Belgium: 32 clinic employees and 32 MSM who did not use antibiotics in the previous 6 months, and 32 MSM who did. Oropharyngeal Neisseria were cultured and identified with MALDI-TOF-MS. Minimum inhibitory concentrations for azithromycin, ceftriaxone and ciprofloxacin were determined using E-tests ® and compared between groups with non-parametric tests. Findings: Non-pathogenic Neisseria from employees as well as MSM were remarkably resistant. Those from MSM were significantly less susceptible than employees to azithromycin (median 7·0 mg/L, IQR 3·0 – 280·2 versus 3·0 mg/L, IQR 2·0 – 4·0, p <0·0001) and ciprofloxacin (0·250 mg/L, IQR 0·020 – 0·380 versus 0·023 mg/L, IQR 0·012 – 0·064, p <0·001), but not ceftriaxone (0·047 mg/L, IQR 0·032 – 0·084 versus 0·034, IQR 0·026 – 0·064, p =0·3). Susceptibility did not differ significantly according to recent antimicrobial exposure in MSM. Interpretation: Surveilling antimicrobial susceptibility of non-pathogenic Neisseria may be a sensitive way to assess impact of antimicrobial exposure in a population. The high levels of antimicrobial resistance in this survey indicate that novel resistance determinants may be readily available for future transfer from non-pathogenic to pathogenic Neisseria. Funding: Belgian Research Foundation - Flanders (FWO 121.00). Declaration of Interests: All authors declare no conflicts of interested related to this work. Ethics Approval Statement: Ethics approval was obtained from ITM’s Institutional Review Board (1276/18 and 1351/20) and from the Ethics Committee of the University of Antwerp (19/06/058 and AB/ac/003).