Molecular Characterization of Invasive Neisseria meningitidis Strains Isolated in Chile during 2010-2011

Background: With the upcoming licensure of Outer Membrane Protein-based vaccines against meningococcal disease, data on disease incidence and molecular characteristic of circulating N. meningitidis strains in Latin American countries is needed. Chile is, to date, one of the few countries in the region that has performed this type of work in a comprehensive collection of disease-associated strains from two consecutive years, 2010-2011. Methods: A total of 119 N. meningitidis strains isolated from patients with invasive disease in Chile in 2010-2011 were characterized by the National Reference Laboratory. Serogroup determination, MLST and porA typing were performed. Results: Serogroup B was predominant in both study years, but W135 experienced a noticeable increase in 2011 compared to 2010. ST-11 complex, ST-41/44 complex ST-32 complex were the most prevalent among the isolates, and were strongly associated with serogroups W135 (ST-11 Complex) and B (ST-41/44 and ST-32 complexes). Likewise, the major porA types detected were strongly associated with these three clonal complexes: P1.5,2 was found exclusively among W135: ST-11 isolates, whereas P1.7, 2-3 was only detected in C: ST-11. ST-41/44 isolates mainly had P1.10-8, and ST-32 complex were associated with a P1.18-8 porA. Conclusions: Our data show disease-associated N. meningitidis circulating in Chile are similar to those found in other parts of the world. The increase on W135: ST-11 isolates observed in 2011 foretold the unusual epidemiological situation experienced in the country in 2012, and MLST data show that this strain is indistinguishable from the one linked to the global Hajj 2000-related outbreak that occurred in 2001. Finally, this work demonstrates the importance of maintaining a strong national surveillance program integrating clinical, epidemiological and laboratory data and incorporating gold standard diagnostic and characterization techniques that allow the data to be compared all over the world.