Prevalence, genomic features, and antibiotic sensitivities of Neisseria meningitidis isolates from patients with invasive meningococcal disease and healthy carriers in Zhejiang Province, 2015-2023.

Objective: A comprehensive understanding of invasive meningococcal disease (IMD) and healthy carriers is critical to monitor, control, and prevent the disease. This study investigated the epidemiology of IMD cases and carriage, and compared population-specific genetic variations and antimicrobial susceptibility of Neisseria meningitidis (N. meningitidis) strains isolated from patients with IMD and carriers.

Methods: Surveillance data from 2015 to 2023 on patients with epidemic meningitis and healthy carriers in Zhejiang Province, China. We successfully collected 21 isolates from meningitis patients and 16 isolates from healthy individuals during this period. Serogroups of a total of 37 N. meningitidis isolates were determined by polymerase chain reaction (PCR) and slide agglutination, as well as whole genome sequencing to assess various genes, single nucleotide polymorphisms (SNPs), and core-pan genome differences. The antibiotic susceptibility of 37 isolates to 12 antibiotics was evaluated using the E-Test on Mueller-Hinton agar supplemented with 5 % sheep blood.

Results: The annual incidence of IMD and carriage rates remained relatively low from 2015 to 2023. IMD cases were primarily observed in infants under 12 months-of-age. Healthy carriers were predominantly 5-9 and 30-59 years-of-age. Population gene analysis revealed no significant difference in genes between the two groups. Strains of patient and carrier groups were both highly resistant to quinolones and sulfonamides.

Conclusions: The findings enhance the understanding of N. meningitidis carriage in the context of prevalent invasive meningococcal strains. The findings will facilitate the development and updating of the immunization program of meningitis vaccine, and are critical in understanding the spread and drug use strategies of N. meningitidis.