Abstract
Background Streptococcus pneumoniae is a leading cause of meningitis in countries where pneumococcal conjugate vaccines (PCV) targeting commonly occurring serotypes are not routinely used. However, effectiveness of PCV would be jeopardized by emergence of invasive pneumococcal diseases (IPD) caused by serotypes which are not included in PCV. Systematic hospital based surveillance in Bangladesh was established and progressively improved to determine the pathogens causing childhood sepsis and meningitis. This also provided the foundation for determining the spectrum of serotypes causing IPD. This article reports an unprecedented upsurge of serotype 2, an uncommon pneumococcal serotype, without any known intervention.Methods and FindingsCases with suspected IPD had blood or cerebrospinal fluid (CSF) collected from the beginning of 2001 till 2009. Pneumococcal serotypes were determined by capsular swelling of isolates or PCR of culture-negative CSF specimens. Multicenter national surveillance, expanded from 2004, identified 45,437 patients with suspected bacteremia who were blood cultured and 10,618 suspected meningitis cases who had a lumber puncture. Pneumococcus accounted for 230 culture positive cases of meningitis in children <5 years. Serotype-2 was the leading cause of pneumococcal meningitis, accounting for 20.4% (45/221; 95% CI 15%–26%) of cases. Ninety eight percent (45/46) of these serotype-2 strains were isolated from meningitis cases, yielding the highest serotype-specific odds ratio for meningitis (29.6; 95% CI 3.4–256.3). The serotype-2 strains had three closely related pulsed field gel electrophoresis types.Conclusions S. pneumoniae serotype-2 was found to possess an unusually high potential for causing meningitis and was the leading serotype-specific cause of childhood meningitis in Bangladesh over the past decade. Persisting disease occurrence or progressive spread would represent a major potential infection threat since serotype-2 is not included in PCVs currently licensed or under development.
Highlights
Streptococcus pneumoniae is estimated to cause .60,000 meningitisassociated deaths plus a poorly defined burden of long-term disability in children #5 years of age world-wide every year [1]
Persisting disease occurrence or progressive spread would represent a major potential infection threat since serotype-2 is not included in pneumococcal conjugate vaccines (PCV) currently licensed or under development
We preliminarily reported a high prevalence of serotype-2 invasive pneumococcal diseases (IPD) in Bangladesh [4], and here we describe in detail S. pneumoniae serotype-2 as a leading cause of childhood pneumococcal meningitis based on 9 years (2001 to 2009) of surveillance
Summary
Streptococcus pneumoniae is estimated to cause .60,000 meningitisassociated deaths plus a poorly defined burden of long-term disability in children #5 years of age world-wide every year [1]. The capsular polysaccharide antigens included in these vaccines are based on the predominant serotypes causing IPD in a variety of settings around the world. This is not ideal for optimizing prevention of IPD in developing countries, since there is little cross-serotype protection and in the developing world and a substantial proportion of IPD is caused by non-vaccine serotypes [3]. Systematic hospital based surveillance in Bangladesh was established and progressively improved to determine the pathogens causing childhood sepsis and meningitis. This provided the foundation for determining the spectrum of serotypes causing IPD. This article reports an unprecedented upsurge of serotype 2, an uncommon pneumococcal serotype, without any known intervention
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