[Moraxella (Branhamella) catarrhalis. A common pathogenic agent].

Moraxella (Branhamella) catarrhalis, a commensal organism of the oropharyngeal flora, has been considered a potential pathogen since the early 1970s, mainly causing otitis in infants and exacerbations of chronic bronchitis in the elderly or in immunosuppressed adults. This view was initially based on the isolation of M. catarrhalis during infections: a density of at least 10(7)/ml of sputum, particularly when it exceeds that of other organisms by at least 100-fold, is considered to indicate the responsibility of M. catarrhalis. The pathogenic potential of M. catarrhalis was proven by the increase in specific serum antibodies (total, IgG, IgA) in patients infected by this organism. Given the large proportion (60 percent) of strains that produce beta-lactamase, antibiotic therapy is based on a combination of amoxycillin and clavulanic acid (or another penicillin/beta-lactamase inhibitor combination) or a third-generation cephalosporin; tetracyclines or macrolides can also be used.