title: Seven valent pneumococcal conjugate vaccine immunization in two Boston communities: changes in serotypes and antimicrobial susceptibility among Streptococcus pneumoniae isolates.
abstract: BACKGROUND
  Seven valent pneumococcal conjugate vaccine (PCV7) was licensed and introduced in 2000 for universal administration of children younger than 2 years of age and for selective immunization of children 2-5 years of age.
  
  
  OBJECTIVE
  To identify changes in colonization and antimicrobial susceptibility among Streptococcus pneumoniae organisms after introduction of PCV7.
  
  
  METHODS
  Infants and children ages 2-24 months were enrolled in surveillance study of nasopharyngeal carriage of S. pneumoniae. Nasopharyngeal cultures for S. pneumoniae were performed at all well child visits and illness visits of children with acute otitis media. S. pneumoniae organisms were serotyped, and antimicrobial susceptibilities to penicillin, amoxicillin, trimethoprim-sulfamethoxazole and azithromycin were performed.
  
  
  RESULTS
  During the 3-year period (October 2000 through September 2003), nasopharyngeal colonization with vaccine serotypes declined from 22% to 2%, and nonvaccine serotypes increased from 7% to 16%. Rates of antibiotic resistance of S. pneumoniae isolates to penicillin, amoxicillin, azithromycin and trimethoprim-sulfamethoxazole were 29.3, 2.2, 26.5 and 28.1%, respectively.
  
  
  CONCLUSIONS
  PCV7 immunization produces a marked decline in vaccine serotypes carried in the nasopharynx of young children, with a coincident rise in the prevalence of nonvaccine serotypes. Important shifts in antimicrobial susceptibility have not been observed to date.
authors.affiliation: Department of Pediatrics, Boston University School of Medicine and Boston Medical Center, Boston, MA, USA.
authors.forename: Stephen I
authors.initials: SI
authors.lastname: Pelton
authors.forename: Anita M
authors.initials: AM
authors.lastname: Loughlin
authors.forename: Colin D
authors.initials: CD
authors.lastname: Marchant
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001900:Boston; D002353:Carrier State; D002675:Child, Preschool; D015331:Cohort Studies; D024881:Drug Resistance, Bacterial; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007223:Infant; D008297:Male; D022401:Meningococcal Vaccines / Q000008:administration & dosage*; D008826:Microbial Sensitivity Tests; D009305:Nasopharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000188:drug therapy / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000302:isolation & purification; D014505:Urban Population; D014611:Vaccination / Q000379:methods
chemical_list: D000900:Anti-Bacterial Agents; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines