Co-infection with Nocardia spp. in a patient with Mycobacterium avium complex pulmonary disease: A case report

Mycobacterium avium complex pulmonary disease (MAC-PD) is sometimes accompanied by co-infection with other pathogenic microorganisms such as Pseudomonas aeruginosa and Haemophilus influenzae. However, co-infection with Nocardia spp. has been rarely reported. We report on a patient diagnosed as having co-infection with Nocardia after treatment for MAC-PD, which was successfully treated using trimethoprim-sulfamethoxazole (TMP-SMX). A 74-year-old woman with MAC-PD was admitted to our hospital to undergo re-examination for pathogenic microorganisms because chest computed tomography (CT) findings did not improve after treatment for MAC-PD. She underwent bronchoscopy and Nocardia spp. was detected from bronchoalveolar lavage fluid culture. Chest CT findings improved after 6 months of treatment using TMP-SMX. Co-infection with other pathogenic microorganisms should be considered when chest CT findings worsen after adequate treatment of MAC-PD. Chest CT findings of Nocardia pulmonary disease in immunocompetent patients can mimic those of MAC-PD and should therefore be differentiated one from the other.