Rhodococcus equi Endocarditis in Prosthetic Valve of a Heart Transplant Recipient

Background: Rhodococcus equi are gram-positive bacteria found in the soil and in animal manure. R. equi infection causes pneumonia and bacteremia predominantly in immunocompromised hosts. Case Summary: A 57-year-old male heart transplant recipient with a bioprosthetic aortic valve presented with 6 weeks of cough, diarrhea, and weight loss. He was found to have cavitary pneumonia and persistent R. equi bacteremia. Transesophageal echocardiogram demonstrated thickening of the bioprosthetic valve with mild regurgitation, and mobile echodensity was later seen on transthoracic echocardiogram. Discontinuation of immunosuppressive medications was associated with clearing of bacteremia, but the patient subsequently developed respiratory failure, possibly due to immune reconstitution inflammatory syndrome. Discussion: To our knowledge, this is the first reported case of R. equi endocarditis in the prosthetic valve of an immunocompromised host. Take-Home Messages: R. equi can cause cavitary pneumonia and bacteremia in immunocompromised hosts, but it should be recognized as a rare cause of endocarditis. Combination antibiotics, management of immunosuppression, and surgical interventions play crucial roles in patient survival.