Diversity and sharing of Haemophilus influenzae strains colonizing healthy children attending day-care centers.
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.
Farjo
Rand S
RS
Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI 48109-0244, USA.
Foxman
Betsy
B
Patel
Mayuri J
MJ
Zhang
Lixin
L
Pettigrew
Melinda M
MM
McCoy
Sandra I
SI
Marrs
Carl F
CF
Gilsdorf
Janet R
JR
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
D004269:DNA, Bacterial