Resumo

Neisseria meningitidis, a causative agent of epidemic bacterial meningitis, is a commensal that colonizes the nasopharynx of 8–20% of healthy individuals. There are five major pathogenic serogroups of N. meningitidis (A, B, C, W135 and Y). N. meningitis C (Nm C) causes a severe disease characterized by inflammation of the meninges, with high lethality and morbidity in the survivors. According to the Brazilian Ministry of Health 7,196 cases of bacterial meningitis were recorded in the country in 2011, 38% confirmed as meningococcal disease. In the state of Minas Gerais (MG), a number of small outbreaks were reported in 2011. Among them, an outbreak occurred in the city of Ouro Branco, in October, affecting 18 people and causing several deaths. Four isolates epidemiologically related to this outbreak and 34 not related but isolated in MG in 2011 were included in this study. The 38 isolates were grouped into three genotypes identified by RAPD-PCR (random amplification of polymorphic DNA), two of them were epidemiological related to the outbreak of Ouro Branco. Eight isolates representing all genotypic, geographic and temporal clusters had their whole genome sequenced by Life Technologies Ion Torrent PGM™. Reference guided draft assemblies of the genomes were accomplished using the softwares TMAP, MIRA3 and CLC Main Workbench. The coding regions were predicted with FgenesB and Prodigal, and the genes were annotated using BLAST2GO. The multilocus sequence types (MLST) were determined by polymorphism analysis of the genes abcZ, adk, aroE, fumC, gdh, pdhC and pgm. Serotypes and serosubtypes were predicted by polymorphism analysis of genes porB and porA. Polymorphisms in our isolates were compared to the international reference database at www.mlst.net. The eight isolates belong to the same MLST type (3780) and clonal complex (ST-103) which is a known invasive lineage. However, the eight isolates can be divided into serosubtype families 14 and 22. Comparative genome analysis involving the eight genomes produced in this study and the 17 complete and publicly available Neisseria genomes is ongoing. The comparative genome approach will contribute to the elucidation of the core and pangenome of N. meningitidis, a condition to the understanding of the population structure and dynamics that drive the emergence of hypervirulent strains in this species.