Bilateral upper lobe Pneumocystis carinii pneumonia in a patient receiving inhaled pentamidine prophylaxis.

A 46-year-old man with AIDS, receiving inhaled pentamidine for Pneumocystis carinii pneumonia (PCP) prophylaxis, developed bilateral upper lobe infiltrates. Bronchoalveolar lavage confirmed the diagnosis of PCP. Therapy with intravenous trimethoprim-sulfamethoxazole (TMP-SMX) was begun, with gradual resolution of these infiltrates noted. An explanation for the development of upper lobe PCP, despite aerosol chemoprophylaxis, is presented and emphasizes the importance of aerosol particle size (and therefore of nebulizer type) on the distribution of inhaled pentamidine.