Emergence of a novel cefotaxime- and ciprofloxacin-resistant strain of serogroup Y Neisseria meningitidis sequence type 23 clonal complex in China.

OBJECTIVES

Neisseria meningitidis is a major pathogen of septicemia and meningitis, with a fatality rate of 10%-15%. Cefotaxime resistance in N. meningitidis remains rare, and has not yet been reported in internationally disseminated serogroup Y (MenY) ST-23 clonal complex (cc23) strains. This study aimed to characterize the molecular epidemiology of a novel cefotaxime- and ciprofloxacin-resistant MenY cc23 clone.

METHODS

During the period of 2023-2025, 10 MenY isolates were collected from patient (n=1), close contact (n=8), and carrier (n=1) in Shanxi, China. The minimum inhibitory concentrations (MICs) of 12 antibiotics were determined by MIC test strip. Whole genome sequencing (WGS) was performed to analyze molecular types, resistance mechanisms, and phylogenetic relationships with other cc23 isolates globally.

RESULTS

Among the 10 MenY isolates, seven were resistant to both cefotaxime (MIC range, 0.75-1 μg/ml) and ciprofloxacin (0.125 μg/ml), intermediate to penicillin (0.19-0.38 μg/ml), and susceptible to ceftriaxone (0.125 μg/ml). These seven isolates shared the fine type Y: P1.5-1,10-1: F4-1: ST-18108 (cc23). WGS analysis revealed that the ST-18108 isolates harbored NEIS1753 allele 5058 (with PBP2 mutations A311V, I312M, V316P, T483S, N512Y, and G545S) and gyrA92 allele (GyrA mutation T91I). NEIS1753_5058 allele phylogenetically clustered with alleles found in N. meningitidis, N. lactamica, and N. cinerea isolates. The nine ST-18108 genomes from this study (n=7) and a previous report from Hebei province (n=2) formed a closely related cluster within the sublineage L23.1, sharing 175 unique single nucleotide polymorphisms (SNPs).

CONCLUSIONS

A novel cefotaxime- and ciprofloxacin-resistant MenY cc23 clone has emerged in China, with an enhanced transmissibility and a higher level of cefotaxime-resistance, potentially challenging the current IMD treatment and chemoprophylaxis strategies across broader geographic regions. Continuous surveillance for this dual-resistant clone is warranted, utilizing molecular markers including ST-18108, NEIS1753_5058 allele, and the 175 SNPs identified in this study.