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Prevalence and genetic diversity of nontypeable haemophilus influenzae in the respiratory tract of infants and primary caregivers.

ABSTRACT: 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.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.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 ?g/mL for amoxicillin and beta-lactamase-positive NTHi with minimum inhibitory concentrations >2 ?g/mL for amoxicillin clavulanate.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.

SUBMITTER: Schumacher SK

PROVIDER: S-EPMC3261374 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

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Prevalence and genetic diversity of nontypeable haemophilus influenzae in the respiratory tract of infants and primary caregivers.

Schumacher Sandra K SK Marchant Colin D CD Loughlin Anita M AM Bouchet Valérie V Stevenson Abbie A Pelton Stephen I SI

The Pediatric infectious disease journal 20120201 2

<h4>Background</h4>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.<h4>Methods</h4>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 caregi ...[more]

PMID: 22051860

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Project description:Although non-typeable (NT) Haemophilus influenzae and Haemophilus haemolyticus are closely related human commensals, H. haemolyticus is non-pathogenic while NT H. influenzae is an important cause of respiratory tract infections. Phase-variable phosphorylcholine (ChoP) modification of lipooligosaccharide (LOS) is a NT H. influenzae virulence factor that, paradoxically, may also promote complement activation by binding C-reactive protein (CRP). CRP is known to bind more to ChoP positioned distally than proximally in LOS, and the position of ChoP within LOS is dictated by specific licD alleles (designated here as licDI, licDIII, and licDIV) that are present in a lic1 locus. The lic1 locus contains the licA-licD genes, and ChoP-host interactions may also be influenced by a second lic1 locus that allows for dual ChoP substitutions in the same strain, or by the number of licA gene tetranucleotide repeats (5'-CAAT-3') that reflect phase-variation mutation rates.Using dot-blot hybridization, 92% of 88 NT H. influenzae and 42.6% of 109 H. haemolyticus strains possessed a lic1 locus. Eight percent of NT H. influenzae and none of the H. haemolyticus strains possessed dual copies of lic1. The licDIII and licDIV gene alleles were distributed similarly (18-22%) among the NT H. influenzae and H. haemolyticus strains while licDI alleles were present in 45.5% of NT H. influenzae but in less than 1% of H. haemolyticus strains (P < .0001). NT H. influenzae had an average of 26.8 tetranucleotide repeats in licA compared to 14.8 repeats in H. haemolyticus (P < .05). In addition, NT H. influenzae strains that possessed a licDIII allele had increased numbers of repeats compared to NT H. influenzae with other licD alleles (P < .05).These data demonstrate that genetic similarities and differences of ChoP expression exist between NT H. influenzae and H. haemolyticus and strengthen the hypothesis that, at the population level, these differences may, in part, provide an advantage in the virulence of NT H. influenzae.

Dataset Information

Prevalence and genetic diversity of nontypeable haemophilus influenzae in the respiratory tract of infants and primary caregivers.

Publications

Prevalence and genetic diversity of nontypeable haemophilus influenzae in the respiratory tract of infants and primary caregivers.

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