title: Relative proportions of Haemophilus species in the throat of healthy children and adults.
abstract: To determine normal proportions of pharyngeal Haemophilus species, qualitative and quantitative mapping of the species in the pharynx of ten healthy children and ten healthy adults was carried out using a selective and a non-selective medium. Haemophilus organisms were present in all samples, comprising approximately 10% of the total cultivable flora (range 0.6-36.9%). Haemophilus parainfluenzae was a member of the normal flora throughout life, constituting 74% of pharyngeal Haemophilus organisms. Haemophilus segnis and Haemophilus paraphrophilus occurred more frequently in samples from adults, whereas Haemophilus haemolyticus was present in only one sample. Non-encapsulated Haemophilus influenzae strains, usually of multiple biotypes, were present in 80% of the children but accounted for a mean of only 1.8% of the total flora. Their number decreased with increasing age; 40% of the adults harbored Haemophilus influenzae but only of a single biotype which constituted a minor proportion of the total flora (mean 0.15%). These findings suggest that host mechanisms can influence changes in the proportions of Haemophilus influenzae strains colonizing the host.
mesh_terms: D000328:Adult; D000375:Aging; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D002648:Child; D002675:Child, Preschool; D006190:Haemophilus / Q000276:immunology / Q000302:isolation & purification*; D006192:Haemophilus Infections / Q000382:microbiology; D006193:Haemophilus influenzae / Q000276:immunology / Q000302:isolation & purification; D006801:Humans; D008875:Middle Aged; D010033:Otitis Media / Q000382:microbiology; D010614:Pharynx / Q000382:microbiology*
chemical_list: D000907:Antibodies, Bacterial