Temporal Trends and Molecular Epidemiology of Recently Described Serotype 6C of Streptococcus pneumoniae

Abstract

We studied the epidemiology of the recently described serotype 6C of Streptococcus pneumoniae among a collection of carriage isolates recovered between 1996 and 2007 in Portugal. Of 4,064 isolates, 106 (2.6%) were of serotype 6C, 17.9% of which were multidrug resistant. The strains were genetically diverse.

Epidemiology of pneumococcal serotype 6A and 6C among invasive and carriage isolates from Alaska, 1986–2009

“…The presence of 8 STs found among only 27 serotype 6C isolates in this study are consistent with other studies that have described a high degree of genetic diversity among this serotype (Campos et al, 2009;Carvalho et al, 2009;Green et al, 2011;Jacobs et al, 2009;Nunes et al, 2009;Rolo et al, 2011b). Of the 8 STs of serotype 6C isolates reported in this study, 4 (1390, 1379, 473, and 1292) have been previously associated with serotype 6A.…”

“…Since then, there have been a number of reports detailing the prevalence, antimicrobial susceptibility patterns, and genetic diversity among serotype 6C isolates collected from both invasive disease and nasopharyngeal colonization studies (Campos et al, 2009;Carvalho et al, 2009;du Plessis et al, 2008;Green et al, 2011;Hermans et al, 2008;Jacobs et al, 2008Jacobs et al, , 2009Nahm et al, 2009;Nunes et al, 2009;Rolo et al, 2011a;Tocheva et al, 2010). In studies that looked at the prevalence of serotype 6C among invasive and carriage isolates, it was found that anywhere between 5% and 100% of isolates that originally typed as 6A were subsequently identified as serotype 6C (Campos et al, 2009;Carvalho et al, 2009;du Plessis et al, 2008;Hermans et al, 2008;Jacobs et al, 2009;Millar et al, 2010;Rolo et al, 2011a).…”

Differential Circulation of Streptococcus pneumoniae Serotype 6C Clones in Two Israeli Pediatric Populations

“…As shown by others (1,4,10), this serotype is frequently found in the NPs of healthy children and is also causing mucosal and invasive diseases. Only 6% of the Sp6C isolates in our study were penicillin nonsusceptible.…”

Validation of Factor 6d Antiserum for Serotyping Streptococcus pneumoniae Serotype 6C

“…Furthermore, they found that this change was present in strains isolated up to 27 years ago and postulated that the 6C capsule type originated more than 27 years ago from a single recombination event in a 6A locus, in which 6A wciN was replaced by a gene of unknown origin. Serotype 6C has subsequently been recognized in several countries and is an important replacement serotype, following the introduction of a conjugate vaccine (3)(4)(5)(6)(7)(8)(9)(10)(12)(13)(14). Recent U.S. surveillance showed a significant 164% increase in the prevalence of invasive disease due to serotype 6C, increasing from 0.22 cases per 100,000 in 1999 to 0.57 and 0.58 cases per 100,000 in 2006 and 2007, respectively, while rates of invasive disease due to serotypes 6A and 6B markedly decreased (3).…”