Abstract
Abstract
Mycobacterium chimaera (MCH) is a non-tuberculous mycobacterium commonly found in the environment. It is a member of the M. avium complex (MAC), and rarely causes infections in humans. However, invasive MCH infections have been reported associated with heater-cooler devices during cardiac surgery. Detection of MCH infections in this setting has been impeded by inadequate clinical awareness and laboratory tests. A 77-year-old man had aorta valve replacement 3 years ago. He recently presented with constitutional symptoms, including fatigue, night sweats, and 50 pounds of weight loss. PET CT showed ground-glass and nodular opacities in the lungs. Bone marrow biopsy demonstrated noncaseating granulomas. Transesophageal echocardiogram revealed severe stenosis and regurgitation of aortic valves. Despite antibiotics and heart surgery to relieve stenosis, the patient succumbed. Autopsy showed multiple small granulomas in the lung and multifocal chronic inflammation in the heart. Premortem mycobacterial cultures of aortic valves were performed, which grew MAC by DNA probe in 1 week. Subsequently, it was identified as MCH by sequencing of the ITS1/ITS2 region. The cause of death was heart failure due to MCH endocarditis. MCH infection is rare but potentially fatal if not promptly treated. Therefore, it is critical to identify patients at risk for infection. Since 2013, over 100 cases of MCH endocarditis have been reported worldwide, specifically associated with contaminated heater-cooler units during heart surgery. Characteristically, MCH infection has a long incubation period after exposure (median 17 months, range 3-72 months). Signs and symptoms are generally nonspecific and often include fatigue, fever, and weight loss. The risk of MCH infection in patients undergoing open heart surgery is low, but clinicians should be aware of the risks especially when heater-cooler units are utilized. A close follow-up over a long period may be necessary due to the long incubation period of this infection.