Why adolescents carry meningitis-causing bacteria

The team from the University's Department of Biology has discovered a novel metabolic pathway in the bacterium Neisseria meningitidis that may explain why this age group is particularly at risk of infection.

The results of the research, which was supported by the Centre for Chronic Diseases and Disorders (C2D2), are reported in the journal Molecular Microbiology.

N. meningitidis is a major cause of meningitis and septicaemia, and a leading cause of infectious disease among teenagers and young adults. While it is well known that these bacteria are found in large numbers in the upper respiratory tract among adolescents, the reasons for this are unknown.

Lead author Dr James Moir, from York's Department of Biology, said: "We have found that N. meningitidis can supplement its growth via metabolism of the small fatty acid propionic acid. The propionic acid is generated by other, strictly anaerobic bacteria (bacteria that do not need oxygen to live) that become more prevalent in adolescents.

"Through our research, we identify the metabolic pathway responsible and show that there is a correlation between N. meningitidis and propionic acid generating anaerobic bacteria Porphyromonas and Fusobacterium. The anaerobes are acquired gradually with age, peaking in adolescence."

Dr Maria-Chiara Catenazzi, from York's Department of Biology, said: "The capacity of N. meningitidis to colonise adolescents/young adults is important for its transmission and disease epidemiology. This increase in carriage in young adulthood is frequently attributed to increased social interaction and contact in this age group. While this is no doubt true, here we present for the first time a mechanistic explanation for why N. meningitidis carriage varies with age, based on the genetic properties of N. meningitidis and co-colonising microbes in the human host."