Haemophilus haemolyticus: A Human Respiratory Tract Commensal to Be Distinguished from Haemophilus influenzae

• Published in: The Journal of infectious diseases Vol. 195; no. 1; pp. 81 - 89
• Main Authors: Murphy, Timothy F., Brauer, Aimee L., Sethi, Sanjay, Kilian, Mogens, Cai, Xueya, Lesse, Alan J.
• Format: Journal Article
• Language: English
• Published: Chicago, IL The University of Chicago Press 01-01-2007; University of Chicago Press
• Subjects: Animal, plant and microbial ecology; Bacteria; Bacteriology; Biological and medical sciences; Chronic obstructive pulmonary disease; Commensals; Fundamental and applied biological sciences. Psychology; Haemophilus; Haemophilus - classification; Haemophilus - isolation & purification; Haemophilus Infections - epidemiology; Haemophilus Infections - microbiology; Haemophilus influenzae; Haemophilus influenzae - classification; Haemophilus influenzae - genetics; Haemophilus influenzae - isolation & purification; Humans; Membrane proteins; Microbial ecology; Microbiology; Miscellaneous; Normal microflora of man and animals. Rumen; Pathogens; Phylogeny; Polymerase chain reaction; Prospective studies; Pulmonary Disease, Chronic Obstructive - complications; Respiratory Tract Infections - microbiology; Ribosomal DNA; Sputum; Sputum - microbiology; Pasteurellaceae; Haemophilus haemolyticus; Human; Infection; Respiratory tract; Commensalism; Animal microorganism relation; Bacteria; Respiratory system; Haemophilus influenzae
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1086/509824

BackgroundHaemophilus influenzae is a common pathogen in adults with chronic obstructive pulmonary disease (COPD). In a prospective study, selected isolates of apparent H. influenzae had an altered phenotype. We tested the hypothesis that these variant strains were genetically different from typical H. influenzae MethodsA prospective study of adults with COPD was conducted. Strains of apparent H. influenzae obtained from a range of clinical sources were evaluated by ribosomal DNA sequence analysis, multilocus sequence analysis, DNA-DNA hybridization, and sequencing of the conserved P6 gene ResultsVariant strains were determined to be Haemophilus haemolyticus by means of 4 independent methods. Analysis of 490 apparent H. influenzae strains, identified by standard methods, revealed that 39.5% of sputum isolates and 27.3% of nasopharyngeal isolates were H. haemolyticus. Isolates obtained from normally sterile sites were all H. influenzae. In a prospective study, acquisitions of new strains of H. haemolyticus were not associated with exacerbations of COPD, whereas 45% of acquisitions of new strains of H. influenzae were associated with exacerbations ConclusionsStandard methods do not reliably distinguish H. haemolyticus from H. influenzae. H. haemolyticus is a respiratory tract commensal. The recognition that some strains of apparent H. influenzae are H. haemolyticus substantially strengthens the association of true H. influenzae with clinical infection