title: Nasopharyngeal carriage of Streptococcus pneumoniae in Taiwan before and after the introduction of a conjugate vaccine.
abstract: BACKGROUND
  The heptavalent pneumococcal conjugate vaccine was introduced in Taiwan in October 2005. To evaluate the effect of the vaccination, we conducted an active, prospective, large-scale, long-term, and multicenter study to assess the prevalence of nasopharyngeal Streptococcus pneumoniae carriage in Taiwanese children.
  
  
  METHODS
  This study was performed at three tertiary teaching hospitals in northern, central, and southern Taiwan. Questionnaires provided demographic, family/household, and medical history data. Pneumococcal isolates were tested for their susceptibility to various antimicrobial agents and serotypes. In addition, influenza virus and Staphylococcus aureus were recovered from nasopharyngeal and nasal swabs, respectively.
  
  
  RESULTS
  Between July 2005 and July 2008, 857 pneumococcal strains were recovered from a total of 6057 children aged >2 months to 5 years (carriage rate, 14.1%). Carriage rates differed geographically and varied with subject age. In a multivariate analysis, having at least one sibling, attendance at day-care centers, a history of otitis media, and history of upper respiratory tract infection in the previous 2 weeks were each associated with a higher risk of pneumococcal colonization of the nasopharynx. Staphylococcus aureus nasal colonization was inversely associated with nasopharyngeal carriage of pneumococcus (p=0.000; odds ratio [OR]: 0.48; 95% CI: 0.39-0.58). Daycare attendance was the only risk factor for carriage of penicillin non-susceptible S. pneumoniae (OR: 2.37; 95% CI: 1.22-4.88). Although vaccination rates rose from 2005 to 2008, no concomitant decrease in S. pneumoniae carriage occurred. The rate of penicillin resistance among S. pneumoniae isolates was 92.8% (using the meningitis criteria). The prevalence of cefotaxime resistance (21.6%) was higher than that of penicillin (6.9%; non-meningitis criteria). Slightly more than half (57.4%) of the isolates belonged to strains covered by the heptavalent pneumococcal conjugate vaccine when both vaccine and vaccine-related serotypes were included.
  
  
  CONCLUSIONS
  Although vaccination rates rose from 2005 to 2008, no concomitant decrease occurred in S. pneumoniae carriage. Interaction between S. aureus and S. pneumoniae may influence vaccination efficacy. These findings provide baseline data to further compare pneumococcal carriage rates and antibiotic resistance patterns in Taiwanese children as vaccination rates continue to increase.
authors.affiliation: Department of Pediatrics, Chang Gung Children's Hospital, College of Medicine, Chang Gung University, 5 Fu-Hsin Street, Kwei-Shan Hsiang, Taoyuan, Taiwan.
authors.forename: Chen-Yen
authors.initials: CY
authors.lastname: Kuo
authors.forename: Kao-Pin
authors.initials: KP
authors.lastname: Hwang
authors.forename: Yu-Chia
authors.initials: YC
authors.lastname: Hsieh
authors.forename: Chi-Hui
authors.initials: CH
authors.lastname: Cheng
authors.forename: Fang-Liang
authors.initials: FL
authors.lastname: Huang
authors.forename: Yea-Huei
authors.initials: YH
authors.lastname: Shen
authors.forename: Yhu-Chering
authors.initials: YC
authors.lastname: Huang
authors.forename: Cheng-Hsun
authors.initials: CH
authors.lastname: Chiu
authors.forename: Po-Yen
authors.initials: PY
authors.lastname: Chen
authors.forename: Tzou-Yien
authors.initials: TY
authors.lastname: Lin
mesh_terms: D002353:Carrier State / Q000453:epidemiology* / Q000276:immunology; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007223:Infant; D009980:Influenza A virus / Q000302:isolation & purification; D008297:Male; D009305:Nasopharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000276:immunology; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D013211:Staphylococcus aureus / Q000302:isolation & purification*; D013296:Streptococcus pneumoniae / Q000276:immunology / Q000302:isolation & purification*; D011795:Surveys and Questionnaires; D013624:Taiwan / Q000453:epidemiology; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate