Leicester Microbial Sciences and Infectious Diseases Centre (LeMID)


Meningitis occurs when an infectious agent crosses the blood-brain barrier and causes inflammation of the meninges, the protective membranous layers surrounding the brain and spinal cord.

We study several of the bacterial pathogens responsible for meningitis including Neisseria meningitidis (the ‘meningococcus’), Streptococcus pneumoniae (the ‘pneumococcus’), Haemophilus influenzae serogroup B and Listeria monocytogenes. Many of these pathogens also cause septicaemia or infections of the bloodstream.


Our research focuses on:

  • epidemiological studies of genetic variability
  • dynamics and determinants of spread of these pathogens
  • phase variation and antigenic variation
  • the virulence factors driving disease
  • immune responses during asymptomatic carriage and disease
  • understanding how vaccines prevent infections

The researchers and examples of specific projects:

Dr Chris Bayliss from the Department of Genetics and Genome Biology is a leading researcher on the meningococcus, specific projects include:

  • Understanding of meningococcal population dynamics afforded by phase variation, allelic variation and recombination in large cohort studies
  • Determining the phenotypic consequences of phase variable gene expression
  • Assessment of vaccine coverage using molecular genetics and whole genome sequencing

Further information

Overview of bacterial meningitis and Neisseria meningitidis

Bacterial meningitis can occur in any age group but tends to have a higher prevalence in infants. Disease is however a rare occurrence with most of the causative organisms commonly being found as harmless commensals in people who are asymptomatically colonised. Streptococcus pneumoniae and Haemophilus influenzae are usually found in the upper respiratory tracts of toddlers whilst Neisseria meningitidis is a frequent commensal of teenagers and young adults. For N. meningitidis, high carriage in this age group is correlated with a minor peak of disease in teenagers and young adults. Asymptomatic carriage elicits a protective immune response that usually prevents the ‘carried strain’ from causing disease. Bacterial meningitis is also rare due to the widespread availability and use of vaccines for many strains of three of the major causative organisms (i.e. Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae).

Back to top