Branhamella catarrhalis pneumonia in patients with immunoglobulin abnormalities.

The importance of Branhamella catarrhalis pneumonia has only recently been appreciated. Predisposing underlying illness associated with this organism have not yet been clarified. We report five cases of Branhamella catarrhalis pneumonia occurring in patients with diseases associated with documented quantitative immunoglobulin deficiencies. Normal immunoglobulins appear to be important host defense mechanisms in preventing infection with this organism.