Etiology of community-acquired bacterial meningitis in children at a tertiary-care centre in Montreal, Canada

Objectives This study aimed to identify the bacteria responsible for community-acquired bacterial meningitis in infants and children.Methods This was a retrospective cohort study including children aged 1 day to 18 years with confirmed bacterial meningitis, evaluated at a tertiary-care, Canadian emergency department between 2014 and 2022. The primary outcome was the pathogen identified. Other variables of interest were complications, age, and diagnostic method. Medical charts were reviewed by a co-investigator and 25% were assessed in duplicate.Results All 79 eligible cases were included. The main causal agents were Group B Streptococcus (GBS) (n = 20; 25%), Streptococcus pneumoniae (n = 16; 20%), Neisseria meningitidis (n = 16; 20%), and Haemophilus influenzae (n = 9; 11%). Etiology exhibited age-dependent variations, with 85% of GBS and 100% of Escherichia coli infections in children under 2 months. All pneumococcal and Group A Streptococcus cases were in children older than 6 months. All children infected by S. pneumoniae were vaccinated but the serotype was not covered by vaccination in 7/8 infections. All children with N. meningitidis were either too young to be vaccinated (n = 10) or infected by a serotype not covered by the given vaccine. Fifty-five bacteria were identified by cerebrospinal fluid culture, 17 by Polymerase Chain Reaction (PCR), and 7 by both methods.Conclusion GBS is now the leading etiology of paediatric community-acquired bacterial meningitis at our centre. The etiology of bacterial meningitis varies greatly by age. Future studies should focus on improving the serotype spectrum of vaccines, identifying strategies to lower GBS infection, and improving the use of PCR as a diagnostic tool.