title: Nontypable Haemophilus influenzae are unencapsulated both in vivo and in vitro.
abstract: Some investigators have suggested that nontypable Haemophilus influenzae isolated from sputum of adults with pneumonia are variant forms of typable H influenzae that have lost their capsule during passage in vitro. We examined colonies of both typable and nontypable H influenzae after they had been grown in vitro, as well as bronchopulmonary secretions from patients with pneumonia or acute, purulent tracheobronchitis due to H influenzae; electron microscopy combined with ruthenium-red staining was used to detect the presence of capsular glycocalyx. H influenzae types a, b, and e', whether grown in vitro or observed directly in bronchopulmonary secretions, had readily detectable capsular glycocalyx external to the cell membrane. In contrast, non-typable H influenzae appeared to be unencapsulated after cultivation in vitro or when directly visualized in bronchopulmonary secretions of infected patients.
mesh_terms: D001991:Bronchitis / Q000382:microbiology; D002462:Cell Membrane / Q000648:ultrastructure; D006023:Glycoproteins / Q000032:analysis*; D006192:Haemophilus Infections / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000032:analysis* / Q000145:classification / Q000648:ultrastructure; D006801:Humans; D008854:Microscopy, Electron; D011014:Pneumonia / Q000382:microbiology; D011134:Polysaccharides / Q000032:analysis*; D012430:Ruthenium Red; D013194:Staining and Labeling
chemical_list: D006023:Glycoproteins; D011134:Polysaccharides; D012430:Ruthenium Red