Genetic analysis of meningococci carried by children and young adults.
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.
Claus
Heike
H
Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany.
Maiden
Martin C J
MC
Wilson
Daniel J
DJ
McCarthy
Noel D
ND
Jolley
Keith A
KA
Urwin
Rachel
R
Hessler
Frank
F
Frosch
Matthias
M
Vogel
Ulrich
U
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