Abstract
Among the over 90 serotypes of Streptococcus pneumoniae described, serotypes 1, 5, and 7F account for a significant proportion of invasive disease worldwide and are now covered by the most recent 10- and 13-valent pneumococcal conjugate vaccines (PCVs). The epidemiology of these serotypes in carriage remains poorly studied because they are rarely detected. We aimed to gain insights into the epidemiology and population structure of serotypes 1, 5 and 7F carried by children in Portugal before PCV10 and PCV13 became widely used. Isolates obtained in cross-sectional studies carried out over a 15-year period (1996–2010) were retrospectively pooled and characterized. Of 5,123 pneumococci obtained, 70 were associated with serotypes 1 (n = 21), 5 (n = 7), and 7F (n = 42). The highest prevalence detected was 3.3% for serotype 1 in 2006, 1% for serotype 5 in 2009, and 3.3% for serotype 7F in 2006; Serotype 1 was associated with PMEN international clones Sweden1-28(ST306) and Sweden1-40(ST304); serotype 5 was associated with Colombia5-19(ST289); and serotype 7F was associated with Netherlands7F-39(ST191). All these isolates were fully susceptible. Most carriers of serotypes 1 (86%), 5 (86%), and 7F (91%) were older than two years but a significant association with older age was only observed for serotype 7F (p = 0.006). Evidence for cross-transmission was obtained. In conclusion, we were able to detect and characterize the rarely carried serotypes 1, 5, and 7F among healthy children in Portugal. These data will constitute an important baseline for upcoming surveillance studies aimed to establish the impact of novel PCVs targeting these serotypes in carriage.
Highlights
Streptococcus pneumoniae is a major human pathogen and a commensal of the human nasopharynx
This study aimed to describe the epidemiology and population structure of serotypes 1, 5 and 7F carried by children in Portugal before the introduction of PCV10 and PCV13
The aim of this work was to describe the epidemiology and the population structure of serotypes 1, 5, and 7F carried by children in Portugal in the years preceding the introduction of PCV10 and PCV13, the first pneumococcal conjugate vaccines targeting these serotypes that became commercially available
Summary
Streptococcus pneumoniae (or pneumococcus) is a major human pathogen and a commensal of the human nasopharynx. S. pneumoniae is a frequent cause of otitis media, pneumonia, bacteremia and meningitis, especially among children under five years of age, the immunocompromised of all ages, and the elderly [1]. The few studies that have looked at the temporal distribution of serotypes over a large time period identified secular trends, which remain poorly understood [10,11]. These serotypes are included in the most recent pneumococcal conjugate vaccines, i.e., the 10-valent and 13-valent pneumococcal conjugate vaccines (PCV10 and PCV13, respectively)
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