Mycobacterium infection from a cardiopulmonary bypass heater-cooler unit in a patient with steroid-induced immunosuppression

Abstract

To present a case of mycobacterium infection transmitted through a heater-cooler unit during cardiac bypass surgery.A 63-yr-old woman with a past medical history of aortic coarctation repair in 1963 and a mechanical aortic valve replacement in 2010 was prescribed antibiotics and steroids at an outpatient care facility in September 2015 for symptoms of an upper respiratory tract infection. Four months later, she developed malaise and intermittent fever with anemia and acute kidney dysfunction. Extensive evaluation revealed negative blood cultures but was suggestive of amyloidosis. The patient was therefore started on systemic steroids prior to being referred to us.At our institution, transesophageal echocardiography and cardiac magnetic resonance imaging revealed a normal mechanical aortic prosthesis with an aortic root abscess. The patient was started on empiric antibiotics for endocarditis. Renal biopsy revealed interstitial nephritis with one granuloma for which she was again started on high-dose steroids. The patient continued to deteriorate, with worsening renal function and pancytopenia that required daily red blood cell and platelet transfusions.Three weeks into this hospitalization, her blood cultures were reported to be positive for Mycobacterium chimera, and she was started on a four-drug regimen of rifampin, rifabutin, ethambutol, and clarithromycin, with dramatic clinical improvement.Heater-cooler units manufactured by LivaNova prior to September 2014 and used during cardiopulmonary bypass have been linked to M. chimera, which causes a latent infection that may be activated and become disseminated in cases of immunosuppression related to steroid use.