title: Genetic analysis of meningococci carried by children and young adults.
abstract: BACKGROUND
  Neisseria meningitidis is a diverse commensal bacterium that occasionally causes severe invasive disease. The relationship between meningococcal genotype and capsular polysaccharide, the principal virulence factor and vaccine component, was investigated in carried meningococci isolated from 8000 children and young adults in Bavaria, Germany.
  
  
  METHODS
  Of the 830 meningococci isolated (carriage rate, 10.4%) by microbiological techniques, 822 were characterized by serogrouping, multilocus sequence typing, and genetic analysis of the capsule region. Statistical and population genetic analyses were applied to these data.
  
  
  RESULTS
  The rapid increase in carriage rates with age of carrier, the low prevalence of hyperinvasive meningococci, and the relative prevalence of the 4 disease-associated serogroups were consistent with earlier observations. There was no genetic structuring of the meningococcal population by age of carrier or sampling location; however, there was significant geographic structuring of the meningococci isolated in civil, but not military, institutions. The rate of capsule gene expression did not vary with age of carrier or meningococcal genotype, except for serogroup C, for which increased expression was associated with ST-11 (formerly ET-37) complex meningococci.
  
  
  CONCLUSIONS
  Serogroup C capsule expression during carriage may contribute to the invasive character of ST-11 complex meningococci and to the high efficacy of meningococcal serogroup C conjugate polysaccharide vaccine.
authors.affiliation: Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Claus
authors.forename: Martin C J
authors.initials: MC
authors.lastname: Maiden
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Wilson
authors.forename: Noel D
authors.initials: ND
authors.lastname: McCarthy
authors.forename: Keith A
authors.initials: KA
authors.lastname: Jolley
authors.forename: Rachel
authors.initials: R
authors.lastname: Urwin
authors.forename: Frank
authors.initials: F
authors.lastname: Hessler
authors.forename: Matthias
authors.initials: M
authors.lastname: Frosch
authors.forename: Ulrich
authors.initials: U
authors.lastname: Vogel
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000483:Alleles; D016667:Bacterial Capsules / Q000235:genetics; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology*; D002648:Child; D002675:Child, Preschool; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008589:Meningococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D009345:Neisseria meningitidis / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D012703:Serotyping