In vitro inhibition of growth of Neisseria gonorrhoeae by Neisseria meningitidis isolated from the pharynx of homosexual men

The Discovery of Oropharyngeal Microbiota with Inhibitory Activity against Pathogenic Neisseria gonorrhoeae and Neisseria meningitidis: An In Vitro Study of Clinical Isolates

With increasing incidence of pathogenic Neisseria infections coupled with emerging resistance to antimicrobials, alternative approaches to limit the spread are sought. We investigated the inhibitory effect of oropharyngeal microbiota on the growth of N. gonorrhoeae and N. meningitidis and the impact of the essential oil-based mouthwash Listerine Cool Mint^® (Listerine). Oropharyngeal swabs from 64 men who have sex with men (n = 118) from a previous study (PReGo study) were analysed (ClinicalTrials.gov, NCT03881007). These included 64 baseline and 54 samples following three months of daily use of Listerine. Inhibition was confirmed by agar overlay assay, and inhibitory bacteria isolated using replica plating and identified using MALDI-TOF. The number of inhibitory isolates were compared before and after Listerine use. Thirty-one pharyngeal samples (26%) showed inhibitory activity against N. gonorrhoeae and/or N. meningitidis, and 62 inhibitory isolates were characterised. Fourteen species belonging to the genera Streptococci and Rothia were identified. More inhibitory isolates were observed following Listerine use compared to baseline, although this effect was not statistically significant (p = 0.073). This study isolated and identified inhibitory bacteria against pathogenic Neisseria spp. and established that daily Listerine use did not decrease their prevalence. These findings could provide a new approach for the prevention and treatment of pharyngeal Neisseria infections.

Risk of Invasive Meningococcal Disease in Men Who Have Sex with Men: Lessons Learned from an Outbreak in Germany, 2012-2013

Background

We undertook investigations in response to an invasive meningococcal disease (IMD) outbreak in men who have sex with men (MSM) in Berlin 2012–2013 to better understand meningococcal transmission and IMD risk in MSM.

Methods

We retrospectively searched for further IMD cases in MSM in Germany through local health departments and undertook exploratory interviews. We performed antigen sequence typing, characterized fHbp and aniA genes of strains with the outbreak finetype and reviewed epidemiologically or spatiotemporally linked cases from 2002–2014.

Results

Among the 148 IMD-cases notified from 01.01.2012–30.09.2013 in 18–59 year-old men we identified 13 MSM in 6 federal states: 11 serogroup C (MenC, all finetype C:P1.5–1,10–8:F3-6), 2 MenB. Interviews with 7 MSM revealed frequent meeting of multiple partners online or via mobile apps and illicit drug use as potential risk factors. MenC incidence was 13-fold higher in MSM than non-MSM. MenC isolates from 9/11 MSM had a novel fHbp allele 766. All C:P1.5–1,10–8:F3-6 strains from MSM versus 16/23 from non-MSM had intact aniA genes (p = 0.04). Although definitive evidence for transmission among MSM in epidemiological or spatiotemporal clusters in 2002–2014 was lacking, clusters were more frequent in men aged 20–49 years. Molecular analysis of C:P1.5–1,10–8:F3-6 strains revealed cases with intact aniA since 2007, mainly associated with fHbp361, fHbp766 and fHbp813, all involving one or more MSM.

Conclusions

MenC incidence was elevated in MSM during the study period. Multiple casual sexual contacts and illicit drug use were common in affected MSM. In all strains from MSM we detected an intact aniA gene coding for a nitrite reductase, which permits survival in microanaerobic environments and could play a role in meningococcal transmission in MSM through urogenital colonization. Furthermore, meningococcal transmission among MSM may be sustained over large areas and thus require modified spatiotemporal scanning algorithms for timely detection and control.