Native-valve Enterococcus hirae endocarditis: a case report and review of the literature

BACKGROUND: Enterococcus hirae is rarely identified in humans and may be a commensal pathogen in psittacine birds. We present the fifth known case of E. hirae endocarditis. CASE PRESENTATION: A 64-year-old Caucasian female presented with fever, hypotension, atrial fibrillation with rapid ventricular response, and a two-week history of lightheadedness. Her previous medical history included COPD, recurrent DVT, atrial fibrillation (on warfarin), hypertension, hypothyroidism, and Hodgkin’s lymphoma. Physical exam was notable for expiratory wheezes and a 2/6 systolic ejection murmur at the right sternal border. 2D echocardiogram revealed severe aortic stenosis. The patient underwent right and left heart catheterization, where she was found to have severe aortic stenosis and mild pulmonary hypertension. She subsequently underwent minimally invasive aortic valve replacement with a bovine pericardial valve, bilateral atrial cryoablation, and clipping of the left atrial appendage. Her aortic valve was found to have a bicuspid, thickened appearance with calcifications, multiple small vegetations, and a root abscess beneath the right coronary cusp. With a new suspicion of infective endocarditis, the patient was placed on broad-spectrum IV antibiotics. Intra-operative blood cultures were negative. A tissue culture from the aortic valve vegetations identified Enterococcus hirae susceptible to ampicillin through MALDI-TOF. Antibiotic treatment was then switched to IV ampicillin and ceftriaxone; she declined aminoglycoside treatment due to toxicity concerns. The patient had an uncomplicated postoperative course and was discharged with 6 weeks of antibiotics. To date, she continues to be followed with no signs of relapsing disease. CONCLUSIONS: To our knowledge, this case constitutes the fifth known case of E. hirae endocarditis, and the second case to have been identified with MALDI-TOF and treated with ampicillin and ceftriaxone. This case reinforces the efficacy of ampicillin and ceftriaxone for the treatment of E. hirae endocarditis.