Coinfection With Nocardia exalbida and Mycobacterium tuberculosis Following Steroid Pulse Therapy: A Case Report and Literature Review

We report a case of pulmonary nocardiosis and pulmonary tuberculosis following steroid pulse therapy for presumed myelitis. A 74-year-old man with transthyretin amyloid cardiomyopathy, chronic heart failure, and type 2 diabetes mellitus received two courses of steroid pulse therapy for suspected inflammatory myelitis. One month later, he developed progressive dyspnea and was admitted to our hospital. Chest computed tomography revealed multifocal right-sided infiltrates and pleural effusion. Although empirical piperacillin/tazobactam was initiated for presumed bacterial pneumonia, sputum Gram and Kinyoun stains revealed thin, branching, partially acid-fast bacilli, and sequencing of the secA1 gene identified Nocardia exalbida. Polymerase chain reaction (PCR) analysis was positive for Mycobacterium tuberculosis. Pleural fluid culture yielded Nocardia species. The patient’s condition improved following combined antituberculous and anti-nocardial therapy, along with optimized heart failure management. Coinfection with nocardiosis and tuberculosis should be considered in immunosuppressed patients following corticosteroid therapy.