title: Invasive pneumococcal disease among adults: associations among serotypes, disease characteristics, and outcome.
abstract: BACKGROUND
  The Streptococcus pneumoniae polysaccharide capsule may be related to invasive pneumococcal disease (IPD) course.
  
  
  METHODS
  We performed a retrospective cohort study with nationally representative surveillance data from 1075 hospitalized patients with IPD from the Netherlands from 1 June 2004 through 31 May 2006 in the prevaccination era. Serotypes were grouped according to invasive disease potential, rate of the most serious clinical syndromes of meningitis and bacteremia without focus, and case-fatality rates. Multivariable logistic regression analysis was performed to obtain odds ratios adjusted for baseline confounders for the association of serotypes and these outcomes, using the serotypes with the lowest rates as reference.
  
  
  RESULTS
  IPD caused by serogroups with low invasive disease potential concerned meningitis or bacteremia without focus in 22% of cases, and 74% of patients had an underlying comorbidity. For highly invasive serogroups these figures were 10% (P < .01) and 56% (P < .01). Individual serotypes varied in the relative rate by which they caused meningitis or bacteremia without focus. Compared with the reference group composed of serotypes 1, 5, 7F, 15B, 20, and 33F, the group of serotypes 3, 19F, 23A, 16F, 6B, 9N, and 18C was associated with increased case-fatality rates (group adjusted odds ratio, 2.6; 95% confidence interval, 1.5-4.7).
  
  
  CONCLUSIONS
  The serotype appeared to be independently associated with IPD severity in adults, which indicates that careful monitoring of IPD after implementation of conjugate vaccines is necessary.
authors.affiliation: Department of Pediatric Immunology and Infectious Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, the Netherlands.
authors.forename: Angelique G S C
authors.initials: AG
authors.lastname: Jansen
authors.forename: Gerwin D
authors.initials: GD
authors.lastname: Rodenburg
authors.forename: Arie
authors.initials: A
authors.lastname: van der Ende
authors.forename: Loek
authors.initials: L
authors.lastname: van Alphen
authors.forename: Reinier H
authors.initials: RH
authors.lastname: Veenhoven
authors.forename: Lodewijk
authors.initials: L
authors.lastname: Spanjaard
authors.forename: Elisabeth A M
authors.initials: EA
authors.lastname: Sanders
authors.forename: Eelko
authors.initials: E
authors.lastname: Hak
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D015331:Cohort Studies; D006760:Hospitalization; D006801:Humans; D008586:Meningitis, Pneumococcal / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011008:Pneumococcal Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D015995:Prevalence; D012189:Retrospective Studies; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000302:isolation & purification / Q000472:pathogenicity*; D016896:Treatment Outcome; D014774:Virulence; D055815:Young Adult