Tonsillectomies are associated with an increased risk of meningococcal carriage.

BACKGROUND Neisseria meningitidis is a commensal organism with the potential to cause life-threatening disease. Colonisation is most common in adolescence and young adulthood. Various social factors have been associated with an increased risk of meningococcal carriage, but less is known about host factors that may influence the carriage status. Tonsillectomies have been shown to alter the pharyngeal microflora. This study assessed whether a history of tonsillectomy affects the risk of meningococcal colonisation. METHODS Oropharyngeal swabs were collected from 15- to 16-year-old adolescents and 18- to 20-year-old young adults. Conventional culture methods and qPCR were used to detect meningococci. 16S qPCR was done to assess bacterial abundance in the samples. Data on history of tonsillectomies were collected from a central national database and the national university hospital. RESULTS A total of 722 samples were collected; 197 from adolescents and 525 from young adults. Thirty-five participants were colonised with meningococci (4.8%). Eighty-eight participants had undergone a tonsillectomy, of which 10 (11.4%) carried meningococci, compared to 4% of those that had not. Prior tonsillectomy was associated with a threefold increased risk of meningococcal colonisation (OR 3.10, 95% CI 1.44-6.70, p = 0.004). Tonsillectomies remained a risk factor after adjusting for age, sex, recent antibiotic use and meningococcal vaccinations (aOR 2.49, 95% CI 1.13-5.48, p = 0.024). CONCLUSIONS A history of tonsillectomy is associated with an increased risk of meningococcal colonisation. More studies are needed to shed light on the effects of tonsillectomies on the pharyngeal microbiome.