title: Prevalence and genetic diversity of nontypeable haemophilus influenzae in the respiratory tract of infants and primary caregivers.
abstract: BACKGROUND
  Nontypeable Haemophilus influenzae (NTHi) causes otitis media, sinusitis, and likely lower respiratory tract infections in children. Colonization, strain diversity, transmission, and antimicrobial susceptibility have implications for both children and their caregivers.
  
  
  METHODS
  For 13 months, we conducted a cross-sectional study of NTHi colonization. Upper respiratory tract cultures were performed in 273 infants and children 2 to 26 months of age and their primary caregivers. NTHi isolates were characterized by multilocus sequence typing (MLST), and antibiotic resistance was examined.
  
  
  RESULTS
  Of the 273 infants, 44 (16.1%) were colonized with NTHi. Prevalence of NTHi varied from 14% in infants less than 6 months of age to 32% in infants between 19 and 26 months of age (P = 0.003). NTHi-colonized infants were more likely to attend day care (30% vs. 12%), have a recent respiratory infection (68% vs. 38%), have recently taken an antibiotic (27% vs. 9%), and have a primary caregiver who reported asthma (11% vs. 1%), compared with other infants (P < 0.01). In the 44 infants colonized with NTHi, we identified 33 different MLSTs. Of the 44 infant-primary caregiver dyads, 9 (20.5%) were colonized with NTHi, and 7 of these 9 shared identical NTHi strains. We also found beta-lactamase-negative NTHi with minimum inhibitory concentrations >2 μg/mL for amoxicillin and beta-lactamase-positive NTHi with minimum inhibitory concentrations >2 μg/mL for amoxicillin clavulanate.
  
  
  CONCLUSIONS
  We found substantial diversity by MLST analysis among NTHi isolates from this community. Infant-primary caregiver dyads usually carried the same strain of NTHi, suggesting that infant-primary caregiver transmission is occurring.
authors: Department of Pediatric Infectious Diseases, Boston University Medical Center, Boston, MA 02118, USA. Sandra.Schumacher@childrens.harvard.edu
authors: Sandra K
authors: SK
authors: Schumacher
authors: Colin D
authors: CD
authors: Marchant
authors: Anita M
authors: AM
authors: Loughlin
authors: Valérie
authors: V
authors: Bouchet
authors: Abbie
authors: A
authors: Stevenson
authors: Stephen I
authors: SI
authors: Pelton
mesh_terms: D017028:Caregivers; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D014644:Genetic Variation; D006192:Haemophilus Infections / Q000453:epidemiology* / Q000382:microbiology; D006193:Haemophilus influenzae / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007223:Infant; D008297:Male; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000382:microbiology