Temporal changes in nasopharyngeal carriage of Streptococcus pneumoniae serotype 1 genotypes in healthy Gambians before and after the 7-valent pneumococcal conjugate vaccine

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1 Vaccinology Theme, Medical Research Council Unit, Banjul, The Gambia
2 Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
3 Disease Control & Elimination Theme, Medical Research Council Unit, Banjul, The Gambia
4 Centre for International Health, School of Medicine, University of Otago, Otago, New Zealand
5 GlaxoSmithKline Vaccines, Wavre, Brussels, Belgium
6 Microbiology and Infection Unit, Warwick Medical School, University of Warwick, Coventry, United Kingdom
DOI
10.7287/peerj.preprints.611v1
Published
Accepted
Subject Areas
Genomics, Microbiology, Epidemiology, Global Health, Infectious Diseases
Keywords
MLST: Multilocus Sequence Typing, PCV-7: 7 valent pneumococcal conjugate vaccine, Invasive Pneumococcal Disease, NPS: Nasopharyngeal Swab, ST: Sequence type, Streptococcus pneumoniae serotype 1, nasopharyngeal carriage, 7-valent pneumococcal conjugate vaccine, Invasive Pneumococcal Disease, Gambia, Multilocus Sequence Typing, Sequence type, ST217 hyper virulent clonal complex, molecular epidemiology
Copyright
© 2014 Ebruke et al.
Licence
This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
Cite this article
Ebruke C, Roca A, Egere U, Darboe O, Hill PC, Greenwood B, Wren BW, Adegbola RA, Antonio M. 2014. Temporal changes in nasopharyngeal carriage of Streptococcus pneumoniae serotype 1 genotypes in healthy Gambians before and after the 7-valent pneumococcal conjugate vaccine. PeerJ PrePrints 2:e611v1

Abstract

Streptococcus pneumoniae serotype 1 is one of the leading causes of invasive pneumococcal disease. However this invasive serotype is hardly found in nasopharyngeal asymptomatic carriage and therefore large epidemiological studies are needed to assess the dynamics of serotype 1 infection. Within the context of a large cluster randomized trial conducted in rural Gambia to assess the impact of PCV-7 vaccination on nasopharyngeal carriage, we present an ancillary study describing the prevalence of nasopharyngeal carriage of pneumococcal serotype 1 and temporal changes of its more frequent genotypes. Nasopharyngeal swabs (NPS) were collected before PCV-7 vaccination (December 2003-May 2004) and up to 30 months after PCV-7 vaccination (post-vaccination periods 1 to 3: July 2006 – March 2007; April 2007 – March 2008 and April 2008 – Feb 2009). S. pneumoniae serotype 1 were genotyped by MLST. Serotype 1 was recovered from 87 (0.71%) of 12,319 NPS samples collected. In the pre-vaccination period, prevalence of serotype 1 was 0.47% in both study arms. In the post-vaccination periods, prevalence in the fully vaccinated villages ranged between 0.08% in period 1 and 0.165% in period 2; while prevalence in partly vaccinated villages was between 0.17% in period 3 and 1.34% in period 2. Overall four different genotypes were obtained with ST3081 the most prevalent (60.71%) followed by ST618 929.76%). ST3081 was found only in post-vaccination period 2 and 3 while ST618 had disappeared in post-vaccination period 3. Distribution of these major genotypes was similar in both study arms.Emergence of ST3081 and concomitant disappearance of ST618 may suggest a change in the molecular epidemiology of pneumococcal serotype 1 in this region. This change is not likely to be associated with the introduction of PCV-7 which lacks serotype 1 as it was observed simultaneously in both study arms. Future population-based epidemiological studies will provide further evidence of substantive changes in the pneumococcal serotype 1 epidemiology and the likely mechanisms.