Enterococcus hirae is a rare isolate in clinical specimens. We describe a case of native aortic-valve endocarditis that was caused by Enterococcus hirae in a 72-year-old man. This is the first reported case of endocarditis due to this organism.
CASE REPORTA 72-year old man presented with a 1-month history of fever, chills, progressive malaise, and generalized weakness. During this period, the patient received several short courses of antibiotics, including trimethoprim-sulfamethoxazole, levofloxacin, and pristinamycin. He had a history of coronary artery disease and, 7 years previously, had undergone percutaneous transluminal coronary angioplasty. On arrival, he was found to have an oral temperature of 36.5°C and a blood pressure of 122/64 mm Hg. Cardiac examination revealed 2/6 systolic and 2/6 diastolic murmurs. Physical examination revealed no evidence of local or systemic infection and no peripheral embolic or immunologic stigmata of infectious endocarditis. Laboratory evaluation showed the following values: white blood cells, 11.6 ϫ 10 9 /liter with 86% neutrophils; hemoglobin, 9.2 g/dl; and platelets, 256 ϫ 10 9 /liter. Examination of cardiac enzymes showed no evidence of myocardial injury. Blood samples of four sets of culture were all positive and yielded an Enterococcus sp. A transesophageal echocardiography showed vegetations involving the left and right aortic-valve leaflets with aortic insufficiency.The isolated strain was identified by phenotypic methods and genetic analysis. In phenotypic analysis, the strain hydrolyzed esculin in the presence of 4% bile and reacted with Lancefield group D antiserum. It was not possible to identify this strain to the species level with the API 20 Strep system (bio-Mérieux, Marcy l'Etoile, France). With the rapid ID 32 Strep system (bioMérieux), which has greater reliability in the identification of enterococci (3), the strain was misidentified as Enterococcus durans. The strain was correctly identified to the species level as Enterococcus hirae by genetic methods using sodA int gene sequencing (7). Sequence analysis of the strains yielded 99.5 and 85.6% identities with the sequences of the type strains of E. hirae (accession no. AJ387916) and E. durans (accession no. AJ387911), respectively. The strain was sensitive to ampicillin (MIC, 0.75 mg/liter; measured by E-test), vancomycin, teicoplanin, and chloramphenicol and resistant to clindamycin, erythromycin, rifampin, and tetracycline and exhibited low-level resistance to streptomycin, kanamycin, and gentamicin.Intravenous ampicillin (200 mg per kg of body weight per day) and gentamicin (3 mg/kg/day) were administered for 4 weeks. Rifampin (25 mg/kg/day) was added 2 weeks after the initiation of antimicrobial treatment for 15 days. The patient improved clinically; and blood cultures performed 1 month later were negative. Five weeks after admission, the patient was discharged from the hospital in good condition and continued to receive oral ampicillin and rifampin for 3 weeks. The patient was readmitted for control ...