title: Diversity and sharing of Haemophilus influenzae strains colonizing healthy children attending day-care centers.
abstract: BACKGROUND
  Children attending day-care centers (DCCs) are at risk for Haemophilus influenzae nasopharyngeal colonization and acute otitis media. The degree to which a given strain circulates within a day-care center and the heterogeneity of strains among DCCs in a geographic area are not well-characterized. This study describes the prevalence rates of H. influenzae colonization in a large number of children attending day-care centers and examines the genetic diversity of colonizing strains and the degree of sharing among children.
  
  
  METHODS
  Throat cultures were collected from 198 healthy children <3 years old attending 16 day-care centers in Michigan. All H. influenzae isolates were genetically typed by enterobacterial repetitive intergenic consensus PCR as the initial screening technique to identify unique strains within each child. Pulsed field gel electrophoresis was used subsequently to examine the genetic diversity of strains between children.
  
  
  RESULTS
  There were 127 (64%) children colonized with H. influenzae. Wide variation in rates of colonization was identified among day-care centers (0 to 95%). A total of 179 genetically unique H. influenzae strains were isolated, and 47 children (37%) were colonized with 2 or more genetically distinct H. influenzae organisms. Evidence of sharing of the same strain in different children was found in 13 of 15 colonized DCCs and 23% of genotypically unique strains were shared.
  
  
  CONCLUSIONS
  The degree of sharing of H. influenzae among children in this study suggests transmission of these potentially pathogenic microorganisms in day-care centers.
authors.affiliation: Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI 48109-0244, USA.
authors.forename: Rand S
authors.initials: RS
authors.lastname: Farjo
authors.forename: Betsy
authors.initials: B
authors.lastname: Foxman
authors.forename: Mayuri J
authors.initials: MJ
authors.lastname: Patel
authors.forename: Lixin
authors.initials: L
authors.lastname: Zhang
authors.forename: Melinda M
authors.initials: MM
authors.lastname: Pettigrew
authors.forename: Sandra I
authors.initials: SI
authors.lastname: McCoy
authors.forename: Carl F
authors.initials: CF
authors.lastname: Marrs
authors.forename: Janet R
authors.initials: JR
authors.lastname: Gilsdorf
mesh_terms: D002353:Carrier State; D002656:Child Day Care Centers; D002675:Child, Preschool; D015331:Cohort Studies; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000032:analysis; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D005838:Genotype; D006192:Haemophilus Infections / Q000517:prevention & control*; D006193:Haemophilus influenzae / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification*; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening; D008824:Michigan; D010033:Otitis Media / Q000382:microbiology / Q000517:prevention & control*; D016133:Polymerase Chain Reaction / Q000379:methods; D012016:Reference Values; D018570:Risk Assessment; D012703:Serotyping
chemical_list: D004269:DNA, Bacterial