title: Pneumococcal population in the era of vaccination: changes in composition and the relation to clinical outcomes.
abstract: BACKGROUND
  Vaccination of infants with pneumococcal conjugate vaccines (PCV) has resulted in major shifts in circulating serotypes.
  
  
  OBJECTIVE
  To investigate the impact of PCV7 on the clonal composition of the pneumococcal population, and the relation of clonal lineages and clinical outcome.
  
  
  METHODS
  By using multiple-locus variable number of tandem repeat analysis, we assessed the pneumococcal populations before (n = 1154), 2-3 years after (n = 1190) and 4-6 years after (n = 1244) the introduction of PCV7 in The Netherlands.
  
  
  RESULTS
  We found statistically significant shifts in clonal lineages within serotypes 1 and 12F based on multiple-locus variable number of tandem repeat analysis results after the implementation of PCV7. Within serotype 12F, the increasing clonal lineage was significantly more associated with pneumonia.
  
  
  CONCLUSIONS
  Shifts in clonal lineages within serotypes could impact the outcomes of pneumococcal disease and fill the niche of the vaccine serotypes.
authors.affiliation: Centre for Infectious Disease Control Netherlands (CIb), National Institute for Public Health & the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Karin E
authors.initials: KE
authors.lastname: Elberse
authors.affiliation: Department of Medical Microbiology & Immunology, St. Antonius Hospital, Nieuwegein, The Netherlands.
authors.forename: Gertjan H J
authors.initials: GH
authors.lastname: Wagenvoort
authors.affiliation: Centre for Infectious Disease Control Netherlands (CIb), National Institute for Public Health & the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Gerlinde N
authors.initials: GN
authors.lastname: Pluister
authors.affiliation: Centre for Infectious Disease Control Netherlands (CIb), National Institute for Public Health & the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Hester E
authors.initials: HE
authors.lastname: de Melker
authors.affiliation: Centre for Infectious Disease Control Netherlands (CIb), National Institute for Public Health & the Environment (RIVM), Bilthoven, The Netherlands.|Department of Immunology & Infectious Diseases, University Medical Center Utrecht, Wilhelmina Children's Hospital, Utrecht, The Netherlands.
authors.forename: Elisabeth A M
authors.initials: EA
authors.lastname: Sanders
authors.affiliation: Department of Medical Microbiology, The Netherlands Reference Laboratory for Bacterial Meningitis, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Arie
authors.initials: A
authors.lastname: van der Ende
authors.affiliation: Centre for Infectious Disease Control Netherlands (CIb), National Institute for Public Health & the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Mirjam J
authors.initials: MJ
authors.lastname: Knol
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine / Q000008:administration & dosage* / Q000276:immunology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D018598:Minisatellite Repeats; D058889:Molecular Typing; D009426:Netherlands / Q000453:epidemiology; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology / Q000517:prevention & control*; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D055815:Young Adult
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine
keywords: MLVA; Streptococcus pneumoniae; capsular switching; clinical outcomes; epidemiology; invasive pneumococcal disease; molecular typing; pneumococcal conjugate vaccine