Significance of Haemophilus spp. and Branhamella catarrhalis in upper respiratory tract infections

Haemophilus influenzae and Branhamella catarrhalis can be considered inhabitants of the upper respiratory tract in humans. Although the pathogenetic role of H. influenzae cannot be discussed, the Authors report the mechanisms of pathogenicity of this microorganism; furthermore, they discuss the direct or indirect pathogenicity of B. catarrhalis in respiratory tract diseases and the ability of both microorganisms to produce beta-lactamases. H. influenzae and B. catarrhalis, together with S. pneumoniae, are the most common bacteria responsible for upper respiratory tract infections, namely otitis and sinusitis. The activity of these bacteria in the onset of otitis and sinusitis is reported.