Rationale: Mycobacterium tilburgii is the causative agent of disseminated non-tuberculosis mycobacterial infections in individuals who are immunocompromised, including those with human immunodeficiency virus infection. Owing to its non-culturable nature, identification of M. tilburgii relies solely on genetic analysis, making reports of M. tilburgii infections rare. We report a case of disseminated M. tilburgii infection complicated by a mixed pulmonary non-tuberculosis mycobacterial infection in a patient with acquired immunodeficiency syndrome. Patient concerns: A male patient in his 40s, diagnosed with human immunodeficiency virus, was admitted with suspected disseminated non-tuberculosis mycobacterial infection based on initial laboratory findings and mycobacterial testing. Mycobacterium intracellulare and Mycobacterium kansasii were detected in the respiratory specimens. Acid-fast staining of the blood and bone marrow samples was positive; however, no bacterial growth was observed in the cultures. Genetic analysis of the blood and bone marrow samples revealed the presence of M. tilburgii . Diagnoses: The patient was diagnosed with disseminated M. tilburgii infection, accompanied by a mixed pulmonary non-tuberculosis mycobacterial infection. Enterococcus faecium , Candida parapsilosis , and Candida glabrata were also detected in blood cultures. Outcomes: Despite ongoing treatment with antibiotics and antifungals, the patient died of septic shock. Lessons: Mycobacterium tilburgii is non-culturable; therefore, when acid-fast bacilli are detected in smear microscopy without subsequent culture growth, clinicians should consider the possibility of M. tilburgii infection and conduct thorough investigations.
Sakai et al. (2026) studied this question.