Branhamella catarrhalis: an unappreciated pulmonary pathogen.

Branhamella catarrhalis is being increasingly identified as an important pulmonary pathogen, particularly in elderly patients with chronic obstructive lung disease. This gram-negative diplococcus can readily be isolated and detected in respiratory secretions. Laboratory identification requires care and beta-lactamase testing. Recognition of lower respiratory tract disease caused by B. catarrhalis is rewarding, since safe and effective therapy exists to treat these patients.