title: Changes in pneumococcal nasopharyngeal colonization among children with respiratory tract infections before and after use of the two new extended-valency pneumococcal conjugated vaccines.
abstract: BACKGROUND
  The 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) and the 13-valent pneumococcal conjugate vaccine (PCV13) replaced the 7-valent PCV (PCV7) in May 2010 in Korea. We investigated the dynamics of pneumococcal nasopharyngeal (NP) colonization in children with a respiratory illness before and after use of PHiD-CV and PCV13.
  
  
  METHODS
  From March 2009 to December 2012 NP secretions were obtained from 2176 children aged < 5 years with respiratory diseases. We used the multiplex polymerase chain reaction (PCR) technique to determine pneumococcal serotypes.
  
  
  RESULTS
  Among the samples, 468 (21.5%) specimens were positive by multiplex PCR. The overall pneumococcal colonization rate remained stable during the 2009-2012 periods. The serotypes present in PCV7 and serotype 19A decreased in frequency from 36.8% and 26.4% in 2009 to 10.1% and 11.4% in 2012, respectively (χ(2) for trend, P < 0.001 and P = 0.007, respectively). The frequency of non-PCV13 serotypes increased from 36.8% in 2009 to 78.5% in 2012 (χ(2) for trend, P < 0.001). There was no significant difference in carriage rates of each serotype between groups of children that received PCV7, PHiD-CV, or PCV13.
  
  
  CONCLUSIONS
  Compared with the period of PCV7 vaccination, overall carriage rate was not affected by the introduction of new PCVs. However, serotype distribution now consists mostly of non-vaccine serotypes. PCVs affect mucosal immunity against Streptococcus pneumoniae (SP) in NP carriage; but, global SP colonization seems to be maintained by replacement.
authors.affiliation: From the 1 Department of Pediatrics, School of Medicine, Ewha Womans University , Seoul , Korea.
authors.forename: Jong Gyun
authors.initials: JG
authors.lastname: Ahn
authors.forename: Seong Yeol
authors.initials: SY
authors.lastname: Choi
authors.forename: Dong Soo
authors.initials: DS
authors.lastname: Kim
authors.forename: Ki Hwan
authors.initials: KH
authors.lastname: Kim
mesh_terms: D002675:Child, Preschool; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine / Q000008:administration & dosage / Q000276:immunology; D006801:Humans; D007223:Infant; D008297:Male; D060885:Multiplex Polymerase Chain Reaction; D009305:Nasopharynx / Q000382:microbiology*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology; D056910:Republic of Korea; D012141:Respiratory Tract Infections / Q000188:drug therapy* / Q000382:microbiology; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D013997:Time Factors
chemical_list: C538862:13-valent pneumococcal vaccine; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; C547294:PHiD-CV vaccine; D022242:Pneumococcal Vaccines
keywords: Streptococcus pneumoniae; nasopharyngeal colonization; pneumococcal conjugate vaccine; serotype