Moraxella (Branhamella) catarrhalis.

Moraxella (Branhamella) catarrhalis is now a well-recognized pathogen in lower respiratory tract infections, particularly in the setting of chronic lung disease. The ability to produce beta-lactamase, which now characterizes most clinical strains, appears to be a recently acquired trait. The most common clinical syndrome caused by this organism is exacerbation of chronic bronchitis; this syndrome has been well described in Europe, Japan, and the United States, particularly from centers with a large elderly population with chronic lung disease. The syndrome of pneumonia is less common, and suppurative complications and bacteremia are rare.