Abstract
Although serogroup 6 was among the first to be recognized among Streptococcus pneumoniae, several new serotypes were identified since the introduction of pneumococcal conjugate vaccines (PCVs). A decrease of the 6B-2 variant among invasive pneumococcal disease (IPD), but not 6B-1, was noted post conjugate vaccine introduction, underpinned by a decrease of CC273 isolates. Serotype 6C was associated with adult IPD and increased in this age group representing two lineages (CC315 and CC395), while the same lineages expressed other serogroup 6 serotypes in children. Taken together, these findings suggest a potential cross-protection of PCVs against serotype 6C IPD among vaccinated children but not among adults. Serotype 6A became the most important serogroup 6 serotype in children but it decreased in adult IPD. No other serogroup 6 serotypes were detected, so available phenotypic or simple genotypic assays remain adequate for distinguishing serotypes within serogroup 6 isolates.
MeSH terms
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Adult
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Anti-Bacterial Agents / pharmacology
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Cross Protection / immunology*
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Heptavalent Pneumococcal Conjugate Vaccine / immunology*
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Humans
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Immunologic Deficiency Syndromes / epidemiology*
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Immunologic Deficiency Syndromes / microbiology
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Interleukin-1 Receptor-Associated Kinases
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Microbial Sensitivity Tests
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Multilocus Sequence Typing
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Pneumococcal Infections / epidemiology*
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Pneumococcal Infections / microbiology
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Pneumococcal Vaccines / immunology*
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Portugal / epidemiology
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Primary Immunodeficiency Diseases
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Serogroup
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Streptococcus pneumoniae / classification
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Streptococcus pneumoniae / genetics*
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Streptococcus pneumoniae / immunology*
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Streptococcus pneumoniae / isolation & purification
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Vaccination
Substances
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10-valent pneumococcal conjugate vaccine
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13-valent pneumococcal vaccine
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Anti-Bacterial Agents
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Heptavalent Pneumococcal Conjugate Vaccine
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Pneumococcal Vaccines
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Interleukin-1 Receptor-Associated Kinases
Supplementary concepts
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IRAK4 Deficiency
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Invasive Pneumococcal Disease, Recurrent Isolated, 2
Grants and funding
J. Diamantino-Miranda and S.I. Aguiar were supported by grants SFRH/BD/81766/2011 and SFRH/BPD/78376/2011, respectively, from Fundação para a Ciência e Tecnologia, Portugal. The work was partly supported by Fundação para a Ciência e Tecnologia, Portugal (PTDC/DTP-EPI/1759/2012 and PTDC/DTP-EPI/1555/2014) and an unrestricted Investigator initiated project from Pfizer. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.