title: Effect of introduction of the pneumococcal conjugate vaccine on drug-resistant Streptococcus pneumoniae.
abstract: BACKGROUND
  Five of seven serotypes in the pneumococcal conjugate vaccine, introduced for infants in the United States in 2000, are responsible for most penicillin-resistant infections. We examined the effect of this vaccine on invasive disease caused by resistant strains.
  
  
  METHODS
  We used laboratory-based data from Active Bacterial Core surveillance to measure disease caused by antibiotic-nonsusceptible pneumococci from 1996 through 2004. Cases of invasive disease, defined as disease caused by pneumococci isolated from a normally sterile site, were identified in eight surveillance areas. Isolates underwent serotyping and susceptibility testing.
  
  
  RESULTS
  Rates of invasive disease caused by penicillin-nonsusceptible strains and strains not susceptible to multiple antibiotics peaked in 1999 and decreased by 2004, from 6.3 to 2.7 cases per 100,000 (a decline of 57 percent; 95 percent confidence interval, 55 to 58 percent) and from 4.1 to 1.7 cases per 100,000 (a decline of 59 percent; 95 percent confidence interval, 58 to 60 percent), respectively. Among children under two years of age, disease caused by penicillin-nonsusceptible strains decreased from 70.3 to 13.1 cases per 100,000 (a decline of 81 percent; 95 percent confidence interval, 80 to 82 percent). Among persons 65 years of age or older, disease caused by penicillin-nonsusceptible strains decreased from 16.4 to 8.4 cases per 100,000 (a decline of 49 percent). Rates of resistant disease caused by vaccine serotypes fell 87 percent. An increase was seen in disease caused by serotype 19A, a serotype not included in the vaccine (from 2.0 to 8.3 per 100,000 among children under two years of age).
  
  
  CONCLUSIONS
  The rate of antibiotic-resistant invasive pneumococcal infections decreased in young children and older persons after the introduction of the conjugate vaccine. There was an increase in infections caused by serotypes not included in the vaccine.
authors.affiliation: Respiratory Diseases Branch, Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, USA.
authors.forename: Moe H
authors.initials: MH
authors.lastname: Kyaw
authors.forename: Ruth
authors.initials: R
authors.lastname: Lynfield
authors.forename: William
authors.initials: W
authors.lastname: Schaffner
authors.forename: Allen S
authors.initials: AS
authors.lastname: Craig
authors.forename: James
authors.initials: J
authors.lastname: Hadler
authors.forename: Arthur
authors.initials: A
authors.lastname: Reingold
authors.forename: Ann R
authors.initials: AR
authors.lastname: Thomas
authors.forename: Lee H
authors.initials: LH
authors.lastname: Harrison
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Bennett
authors.forename: Monica M
authors.initials: MM
authors.lastname: Farley
authors.forename: Richard R
authors.initials: RR
authors.lastname: Facklam
authors.forename: James H
authors.initials: JH
authors.lastname: Jorgensen
authors.forename: John
authors.initials: J
authors.lastname: Besser
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Zell
authors.forename: Anne
authors.initials: A
authors.lastname: Schuchat
authors.forename: Cynthia G
authors.initials: CG
authors.lastname: Whitney
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007223:Infant; D022401:Meningococcal Vaccines; D008875:Middle Aged; D010403:Penicillin Resistance; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D022242:Pneumococcal Vaccines; D011159:Population Surveillance; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D014481:United States / Q000453:epidemiology
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines