Branhamella catarrhalis as a lower respiratory tract pathogen in patients with chronic lung disease.

To determine the possible role of Branhamella (formerly Neisseria) catarrhalis as a respiratory pathogen, we screened quality sputa (defined by cellular criteria) that showed numerous gram-negative cocci on Gram's stain for the presence of B catarrhalis. In an eight-month period, 52 isolates of B catarrhalis were identified in adults attending a hospital for chest diseases. During this period B catarrhalis was the third most common potential pathogen isolated from sputa. Twenty-two patients (42%) had associated patchy bronchopneumonic or lobar infiltrates. All had negative blood cultures and a generally mild clinical course. The majority of strains (73%) of B catarrhalis produced beta-lactamase and were resistant to penicillin and ampicillin. Isolates (including beta-lactamase-producing strains) were susceptible to erythromycin, tetracycline, and trimethoprim-sulfamethoxazole. These studies demonstrate that in patients with chronic lung disease, the presence of B catarrhalis in sputum can be suspected on the basis of a Gram's stain and may be associated with the development of new pneumonic infiltrates. Since these organisms frequently produce beta-lactamase, empiric antimicrobial therapy should include agents other than the penicillins.