Disseminated Tuberculosis With Presumptive Tricuspid Valve Endocarditis Presenting as Culture-Negative Infective Endocarditis: A Clinical Diagnostic Challenge

Tuberculous endocarditis is a rare manifestation of Mycobacterium tuberculosis and may present as blood culture-negative infective endocarditis (BCNE). A 34-year-old male with no prior documented immunosuppressive illness or comorbidities, resident of Raisen district, Madhya Pradesh - a high tuberculosis (TB)-burden region - presented with a three-month history of intermittent high-grade fever, night sweats, and significant weight loss. Examination revealed pallor and tender cervical lymphadenopathy. Laboratory evaluation showed anaemia, leukopenia (WBC 2.85 × 10³/μL), elevated ferritin (640.60 ng/mL), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), while repeated pre-treatment blood and urine cultures were sterile. Chest radiograph revealed bilateral hilar lymphadenopathy. Echocardiography, performed in the context of a newly auscultated tricuspid regurgitation murmur and persistent fever despite broad-spectrum antibiotics, demonstrated flail tricuspid valve leaflets with vegetations consistent with infective endocarditis. Bone marrow biopsy showed epithelioid granulomas with Langhans-type giant cells. Contrast-enhanced computed tomography (CECT) of the thorax and abdomen revealed necrotic mediastinal lymphadenopathy, hepatic granulomas, abdominal (periportal and paraaortic) lymphadenopathy, and pulmonary tree-in-bud nodules. The spleen was unremarkable. Bronchoalveolar lavage cartridge-based nucleic acid amplification test (CBNAAT) detected rifampicin-sensitive M. tuberculosis, confirming disseminated TB. A diagnosis of disseminated TB with presumptive tricuspid valve endocarditis was made. The patient responded rapidly to first-line antituberculous therapy (HRZE (isoniazid, rifampin, pyrazinamide, and ethambutol) × two months, followed by HR (isoniazid and rifampin) × 10 months; total 12 months) with adjunctive corticosteroids, becoming afebrile within a week. We report this case to highlight M. tuberculosis as a rare but important aetiology of culture-negative endocarditis, particularly in patients from TB-endemic regions, and to illustrate the clinical reasoning required when valve tissue cannot be obtained for confirmation.