Background: Neisseria meningitidis remains a global concern and a leading cause of bacterial meningitis and sepsis. This study characterizes the molecular profiles and resistance mechanisms of N. meningitidis isolates collected as a part of surveillance in South India and to assess public‑health implications, including travel‑associated spread and vaccination needs.
Methods: Five N. meningitidis isolates from Indian cities (Bangalore, Chennai, Calicut, and Vellore) collected during the year 2024-2025. Genomic characterisation was done for all the isolates – gene/allele annotation (ctrA/serogroup, MLST, PorA, FetA, PorB, BAST, fHbp, NHBA, NadA) and screening for resistance‑associated alleles (penA, gyrA, folP, mtr locus, norM, farB). Metadata included location, year, source, and disease status. Typing results were compared with known clonal complexes and publicly available references.
Results: Isolates comprised of serogroups W135 (n=2), B (n=2), and NG (n=1). W:cc11 isolates shared identical PorA (5,2), FetA (F1‑1) and similar antigenic profiles. Serogroup-B isolates displayed diverse PorA/FetA combinations and lacked NadA. The NG ST‑175 isolate carried fHbp 111. Resistance‑associated alleles were widespread: multiple penA substitutions (A510V, F504L, H541N, I515V, I566V) present across isolates, gyrA substitutions (T91I, T173A) in select isolates, and folP variants (F31L, G194C/G194GSG, P68A/S, R228S). Efflux and transport loci (mtrA/C/F/R, norM, and farB) were detected in most isolates, suggesting potential reduced susceptibility to penicillin, sulfonamides, and fluoroquinolones.
Conclusion: This small South Indian collection reveals circulation of the hypervirulent strain SG-W135:cc11 and diverse B and NG lineages harbouring multiple resistance‑associated alleles. The presence of novel BAST combinations in W:cc11 and widespread penA/gyrA/folP variants underscores the value of integrated antigenic and resistance genotyping for regional surveillance and vaccine-coverage assessment. Expanded genomic surveillance with cgMLST and phenotypic susceptibility testing is recommended to define transmission links, antimicrobial resistance phenotypes, and predicted coverage by MenB vaccines.