Molecular epidemiology of pneumococci obtained from Gambian children aged 2–29 months with invasive pneumococcal disease during a trial of a 9-valent pneumococcal conjugate vaccine

Abstract

Background: The study describes the molecular epidemiology of Streptococcus pneumoniae causing invasive disease in Gambian children

High-Level Genetic Diversity among Invasive <i>Streptococcus pneumoniae</i> Isolates in Turkey

“…Further, comparison of our strains with those in the global pneumococcal MLST database resulted in the classification of 45 strains into 20 CCs and 5 singletons, thus confirming the high diversity within the global pneumococcal MLST database. Results of several studies performed in different countries also indicate high-level heterogeneity among the pneumococcal population (5,9,17,18). Turkish strains also show very heterogeneous global distribution (20).…”

“…Previous studies have shown that isolates within the same clone express different capsular serotypes because of the natural transformation of pneumococcal DNA (9,18,21). This phenomenon (called capsular switching) results in the emergence of a clone with a different capsular type (18).…”

“…This phenomenon (called capsular switching) results in the emergence of a clone with a different capsular type (18). If such a capsular switch results in the expression of a capsule not recognized by an available vaccine, it may lead to increased rates of IPD (4).…”

“…The overall PNSP rate of pneumococcal isolates in our study was 19.1z, which was similar to that reported in other parts of the world, including 9z-24z in North America and 0z-43z in Europe (26,27). Antimicrobial resistance of pneumococci is closely linked to both their serotype and genotype (18). A multidrug resistant (MDR) clone of serotype 23F S. pneumoniae has spread from Spain to other countries (28,29).…”

“…Classically, serotyping is used for typing and investigating the epidemiology of pneumococci (17,18). MLST is an internationally accepted method for monitoring the distribution of clones through the pneumococcal population (19).…”