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Characterization of Unusual Serogroups of Neisseria meningitidis
Samy Taha1, Giulia Fantoni1,2, Eva Hong1
1Institut Pasteur, Invasive Bacterial Infections, Université Paris Cité, 75015 Paris, France.
Abstract:
Most cases of invasive meningococcal disease (IMD) in Europe are caused by isolates of the Neisseria meningitidis serogroups B, C, W, and Y. We aimed to explore cases caused by other unusual serogroups. We retrospectively screened IMD cases in the databases of the National Reference Center for Meningococci and Haemophilus influnezae in France between 2014 and 2023. Age, sex, serogroups, and genetic lineage distributions were analyzed. We also measured complement deposition on the bacterial surface and tested coverage by vaccines against serogroup B. Cases due to isolates of serogroups other than B, C, W, and Y represented 1.6% of all 3610 IMD cases during the study period with 59 cases and a median age of 21.5 years of age. The corresponding isolates were non-groupable (26 cases), serogroup X (21 cases), serogroup E (11 cases), and one isolate belonged to serogroup Z. Only a low proportion (7.4%) belonged to the hyperinvasive genetic lineages. Isolates of serogroup E bound a significantly higher amount of complement on their surface and were mainly detected in patients with terminal complement pathway deficiencies. Isolates of these unusual serogroups were shown to be covered by vaccines licensed against meningococci B. Surveillance of these isolates needs to be enhanced.
Insights
Invasive meningococcal disease (IMD) cases caused by unusual Neisseria meningitidis serogroups are rare but require enhanced surveillance. Serogroup E isolates showed increased complement deposition, particularly in deficient patients.
Area of Science:
- Microbiology
- Epidemiology
- Immunology
Background:
- Invasive meningococcal disease (IMD) is primarily caused by Neisseria meningitidis serogroups B, C, W, and Y in Europe.
- Emerging or less common serogroups of N. meningitidis can cause significant public health concerns.
Purpose of the Study:
- To investigate the epidemiology and characteristics of IMD cases caused by unusual N. meningitidis serogroups in France.
- To analyze the genetic lineages, complement deposition, and vaccine coverage of these uncommon serogroups.
Main Methods:
- Retrospective analysis of IMD cases from the French National Reference Center for Meningococci database (2014-2023).
- Characterization of isolates including serogroup, genetic lineage, and surface complement deposition.
- Assessment of vaccine cross-coverage against serogroup B.
Main Results:
- Unusual serogroups accounted for 1.6% (59/3610) of IMD cases, with non-groupable, X, E, and Z being identified.
- Serogroup E isolates demonstrated higher complement deposition and were associated with terminal complement pathway deficiencies.
- A low proportion of these isolates belonged to hyperinvasive genetic lineages (7.4%).
Conclusions:
- While rare, IMD cases caused by unusual meningococcal serogroups occur and warrant increased surveillance.
- Serogroup E warrants specific attention due to its interaction with the complement system.
- Existing vaccines against serogroup B may offer cross-protection against these unusual serogroups.
