Phenotypic and genomic surveillance of invasive Neisseria meningitidis isolates in Argentina (2015-2022): Clonal structure and vaccine implications.

Invasive meningococcal disease is associated with high fatality rates and disabling sequelae. The aims of this study were to describe the phenotypic and genotypic characteristics of invasive Neisseria meningitidis isolates in Argentina, determine the genomic population structure and evaluate the potential coverage of vaccines targeting N. meningitidis serogroup B (MenB). During the period 2015-2022, a total of 444 isolates of N. meningitidis causing invasive disease were assessed through laboratory surveillance; 344 isolates were available for whole genome sequencing characterization. The presence of antimicrobial resistance genes, and the distribution of clonal complexes and vaccine antigens were analyzed. MenB was the most frequent serogroup (53.2%), followed by MenW (32.0%). Most isolates were susceptible to the antimicrobial agents tested; however, 56.7% exhibited intermediate resistance to penicillin. MenB showed wide genetic diversity and was mainly associated with ST-865 cc, ST-35 cc, ST-41/44 cc, and ST-32 cc. Unlike other countries, in Argentina, ST-865 cc was one of the major clonal complexes associated with MenB, MenW was only associated with ST-11 cc. To study the potential coverage of vaccines targeting MenB, we used the MenDeVAR (Meningococcal Deduced Vaccine Antigen Reactivity) index, which provides information on the presence and possible immunological cross-reactivity of the different vaccine antigenic variants. MenDeVar showed 19.3% vaccine reactivity for 4CMenB and 40.0% for the bivalent vaccine. Laboratory surveillance is essential for generating evidence-based decisions for updating vaccination strategies.