title: Effect of seven-valent pneumococcal conjugate vaccine on Staphylococcus aureus colonisation in a randomised controlled trial.
abstract: BACKGROUND
  Heptavalent pneumococcal conjugate vaccine (PCV7) shifts nasopharyngeal colonisation with vaccine serotype pneumococci towards nonvaccine serotypes. Because of the reported negative association of vaccine serotype pneumococci and Staphylococcus aureus in the nasopharynx, we explored the effect of PCV7 on nasopharyngeal colonisation with S. aureus in children and parents.
  
  
  RESULTS
  This study was part of a randomised controlled trial on the effect of PCV7 on pneumococcal carriage, enrolling healthy newborns who were randomly assigned (1:1:1) to receive PCV7 (1) at 2 and 4 months of age (2) at 2, 4 and 11 months or (3) no PCV7 (controls). Nasopharyngeal colonisation of S. aureus was a planned secondary outcome. Nasopharyngeal swabs were obtained from all children over a 2-year period with 6-months interval and from one parent at the child's age of 12 and 24 months and cultured for Streptococcus pneumoniae and S. aureus. Between July 2005 and February 2006, 1005 children were enrolled and received either 2-doses of PCV7 (n = 336), 2+1-doses (336) or no dose (n = 333) before PCV7 implementation in the Dutch national immunization program. S. aureus colonisation had doubled in children in the 2+1-dose group at 12 months of age compared with unvaccinated controls (10.1% versus 5.0%; p = 0.019). A negative association for co-colonisation of S. pneumoniae and S. aureus was observed for both vaccine serotype (adjusted odds ratio (aOR) 0.53, 95% confidence interval (CI) 0.38-0.74) and nonvaccine serotype pneumococci (aOR 0.67, 95% CI 0.52-0.88).
  
  
  CONCLUSIONS
  PCV7 induces a temporary increase in S. aureus colonisation in children around 12 months of age after a 2+1-dose PCV7 schedule. The potential clinical consequences are unknown and monitoring is warranted.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT00189020.
authors.affiliation: Department of Pediatric Immunology and Infectious Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands. e.j.m.vangils@umcutrecht.nl
authors.forename: Elske J M
authors.initials: EJ
authors.lastname: van Gils
authors.forename: Eelko
authors.initials: E
authors.lastname: Hak
authors.forename: Reinier H
authors.initials: RH
authors.lastname: Veenhoven
authors.forename: Gerwin D
authors.initials: GD
authors.lastname: Rodenburg
authors.forename: Debby
authors.initials: D
authors.lastname: Bogaert
authors.forename: Jacob P
authors.initials: JP
authors.lastname: Bruin
authors.forename: Loek
authors.initials: L
authors.lastname: van Alphen
authors.forename: Elisabeth A M
authors.initials: EA
authors.lastname: Sanders
mesh_terms: D002675:Child, Preschool; D015169:Colony Count, Microbial; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007223:Infant; D009305:Nasopharynx / Q000382:microbiology; D009426:Netherlands; D016017:Odds Ratio; D011008:Pneumococcal Infections / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000276:immunology*; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000254:growth & development* / Q000276:immunology*; D013296:Streptococcus pneumoniae / Q000276:immunology
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines