Pulmonary nocardiosis caused by Nocardia exalbida complicating Pneumocystis pneumonia in an HIV-infected patient

A 47-year-old man with optimally controlled type-2 diabetes mellitus and chronic hepatitis B was admitted to a local hospital because of a 1-week history of cough and high-grade fever. He was diagnosed with Pneumocystis pneumonia (PCP) and Klebsiella pneumonia from a chest radiograph and sputum. Simultaneously, he was found to have HIV infection with a CD4 count of 76/μl. Despite alteration of treatment secondary to the development of allergic reaction to trimethoprim-sulfamethoxazole (TMP-SMX), the patient was able to complete a 3-week therapy for PCP after being switched to pentamidine isetionate. After the treatment of PCP, he was referred to our hospital for the initiation of anti-HIV therapy. He presented with recurrent high-grade fever of a few days' duration prior to his initial visit, which subsequently led to his admission. Chest computed tomography (CT) showed the enlargement of a previously identified infiltrate in the left upper lung field, and the sputum culture upon admission was positive for Gram-positive branching rods; the organism was later identified as Nocardia exalbida. Due to his allergy to sulfonamide, the patient was treated with imipenem (IMP) and amikacin (AMK) given intravenously for 17 days, followed by garenoxacin (GRNX) taken orally for 6 months, without any adverse effects. The chest infiltrate resolved completely, and he remains stable without relapse 8 months after the completion of the therapy. Pulmonary nocardiosis should be considered as a differential diagnosis of recurring pneumonia in immunocompromised patients, especially in HIV-infected individuals. Oral administration of GRNX following IMP and AMK can be used as an alternative to TMP-SMX therapy in cases of pulmonary nocardiosis caused by N. exalbida.