Branhamella catarrhalis pneumonia and immunoglobulin abnormalities: a new association.

A case of Branhamella catarrhalis pneumonia in a patient with multiple myeloma is reported. With the inclusion of this case, 5 of 17 (29.4%) reported cases of Branhamella pneumonia or empyema have occurred in patients with underlying diseases associated with immunoglobulin abnormalities. This strong clinical association suggests that qualitatively and quantitatively normal immunoglobulins are important host defense mechanisms in preventing infection with this pathogen. The sputum Gram stain demonstrating kidney-shaped gram-negative diplococci may be an early clue to the diagnosis, as well as an initial guide to empiric therapy, and may help the laboratory isolate and identify this pathogen, which, because of its morphologic resemblance to Neisseria, is frequently reported as "normal flora".