title: Changes in the Population Structure of Invasive Neisseria meningitidis in the United States After Quadrivalent Meningococcal Conjugate Vaccine Licensure.
abstract: BACKGROUND
  Meningococcal conjugate vaccines against serogroups A, C, W, and Y (MenACWY) are recommended for routine use in adolescents aged 11-18 years. The impact of these vaccines on the meningococcal population structure in the United States have yet to be evaluated.
  
  
  METHODS
  Meningococcal isolates recovered during 2006-2010 (ie, after introduction of MenACWY) collected through Active Bacterial Core surveillance (ABCs) were characterized; serogroup distribution and molecular features of these isolates were compared to previously published data on ABCs isolates recovered from 2000 to 2005 (ie, before introduction of MenACWY). P values were generated using χ(2) statistics and exact methods.
  
  
  RESULTS
  There was a significant change (P < .05) in serogroup distribution among all age groups between the 2 periods. A small proportion of isolates showed evidence of capsular switching in both periods. Between the 2 periods, significant changes were observed in the distribution of porin A, ferric enterobactin transport, and strain genotypes among vaccine and nonvaccine serogroups.
  
  
  CONCLUSIONS
  The population structure of US meningococcal isolates is dynamic; some changes occurred over time, but the basic structure remained. Vaccine-induced serogroup replacement was not observed, although a small proportion of isolates had undergone capsule switching, possibly driven by non-vaccine-mediated selection. Changes in the distribution of molecular features are likely due to horizontal gene transfer and changes in serogroup distribution.
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Infectious Diseases Epidemiology Research Unit, University of Pittsburgh School of Medicine and Graduate School of Public Health, Pennsylvania.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Shutt
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Jeni T
authors.initials: JT
authors.lastname: Vuong
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Amanda
authors.initials: A
authors.lastname: Cohn
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Jessica
authors.initials: J
authors.lastname: MacNeil
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Susanna
authors.initials: S
authors.lastname: Schmink
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Brian
authors.initials: B
authors.lastname: Plikaytis
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Messonnier
authors.affiliation: Infectious Diseases Epidemiology Research Unit, University of Pittsburgh School of Medicine and Graduate School of Public Health, Pennsylvania.
authors.forename: Lee H
authors.initials: LH
authors.lastname: Harrison
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Clark
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Leonard W
authors.initials: LW
authors.lastname: Mayer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008589:Meningococcal Infections / Q000453:epidemiology* / Q000382:microbiology* / Q000517:prevention & control; D022401:Meningococcal Vaccines / Q000008:administration & dosage*; D008875:Middle Aged; D009345:Neisseria meningitidis / Q000145:classification* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D065288:Serogroup; D014481:United States; D018074:Vaccines, Conjugate / Q000008:administration & dosage; D055815:Young Adult
chemical_list: C525703:MenACWY; D022401:Meningococcal Vaccines; D018074:Vaccines, Conjugate
keywords: meningococcal disease; molecular epidemiology; vaccine impact