Variability of antimicrobial susceptibility of commensal Neisseria species supports its use as a marker of excessive antimicrobial consumption – reflections from the results of a four-country study

This perspective explores the utility of commensal Neisseria species as an early warning sign of excessive antimicrobial consumption. Little is known as to how the prevalence and antimicrobial susceptibility of various commensal Neisseria species varies between populations around the world. We compared the prevalence and antimicrobial susceptibilities of oral commensal Neisseria species in the general population and cohorts of men who have sex with men (MSM) in four countries with available data – Belgium, Italy, Japan and Vietnam. In individuals where Neisseria spp. were detected, N. subflava was present in 70-100% of individuals in the different studies. The N. subflava azithromycin and ciprofloxacin minimum inhibitory concentrations (MICs) were higher in the MSM than in the general population. The MICs of all Neisseria spp. were very similar in the general populations of Belgium and Italy. For all Neisseria spp., azithromycin and ceftriaxone MICs were higher, whereas ciprofloxacin MICs were lower in Belgium and Italy than in Japan. The higher azithromycin and ciprofloxacin MICs observed in the cohorts of MSM compared to the general population and the higher ciprofloxacin MICs in Japan compared to Belgium and Italy are commensurate with the most commonly antimicrobial prescribed in these populations. Our results support using commensal Neisseria species as an early warning system of excessive antimicrobial consumption.