Advanced systolic heart failure and Mycobacterium avium complex (MAC) infection: Proposed immunologic mechanism, diagnostic dilemma and treatment considerations

Abstract

Mycobacterium avium complex (MAC) infection is well recognized in patients with cellular immunodeficiency. Recognition of its morbidity in non-immunocompromised patients has emerged in the last few decades. Underlying chronic pulmonary disease, bronchiectasis, cigarette smoking, cystic fibrosis and chest wall deformities are well-recognized predisposing conditions. Weight loss, dyspnea, cough, fatigue and sputum production are the most common presenting symptoms. We present a case of culture proven MAC infection in an elderly female whose dyspnea and fatigue for a considerable period was inappropriately attributed to chronic heart failure exacerbations necessitating frequent hospital admissions. Despite optimal medical management, clinical improvement was not achieved until a broncho-alveolar lavage (BAL) culture grew MAC and antibiotic therapy targeted against MAC was introduced. Our case report proposes chronic systolic heart failure as a new (not well-recognized) predisposing condition for MAC infection in elderly patients. Because clinical diagnosis can be delayed for weeks, we recommend obtaining sputum/BAL cultures if no clinical improvement is achieved in heart failure patients despite optimal management. High Resolution Computerized Tomography (HRCT) of the chest may also provide meaningful information. We also emphasize the importance of adjusting antibiotics, especially clarithromycin (CLR), based on renal function and tailoring antibiotic management according to serum drug levels to avoid potential liver toxicity associated with CLR use.