The Underestimated Threat-Mycobacterium Genavense Infection: A Case Report

Nontuberculous mycobacteria (NTM) represent a heterogeneous group of pathogens with increasing global prevalence and significant geographical variation in species distribution. NTM infections, often affecting immunocompromised individuals, are difficult to diagnose due to nonspecific clinical presentations and laboratory findings. This case study presents a rare extrapulmonary NTM infection in a 73-year-old man, initially misdiagnosed as sarcoidosis, highlighting the diagnostic and therapeutic challenges posed by such infections.

The patient, a pigeon fancier, presented with recurrent fever and pancytopenia. Extensive diagnostics included blood cultures, bone marrow aspiration, and histopathology. Initial cultures and serological tests remained negative.

Bone marrow aspiration revealed epithelioid granulomas, initially leading to the provisional diagnosis of sarcoidosis. However, after six weeks, M. genavense was isolated from mycobacterial blood cultures from bone marrow aspirant. Antimicrobial therapy with azithromycin, rifampicin, and ethambutol was initiated. Following the initiation of appropriate antimycobacterial therapy, the patient developed immune reconstitution inflammatory syndrome (IRIS), which was managed with supportive care. The patient's condition improved, and no further febrile episodes occurred post-treatment, marking the successful conclusion of NTM therapy.

This case underscores the diagnostic complexity of extrapulmonary NTM infections, particularly in immunocompromised patients. Misdiagnosis can delay appropriate treatment. M. genavense, though rare, should be considered in patients with a fever of unknown origin, especially with a background of immunosuppression. Prompt mycobacterial testing and tailored antibiotic therapy are crucial to improving outcomes in NTM infections.