We describe a case of infective endocarditis in a prosthetic mitral valve due to Ochrobactrum anthropi. Although O. anthropi is an emerging pathogen in immunocompromised patients, infections with the bacterium have very rarely been documented in healthy hosts, and endocarditis is rare. To our knowledge, only two cases of O. anthropi endocarditis have been reported in the medical literature.
CASE REPORTA 65-year-old woman was admitted to our hospital in November 2002 with a 3-day history of fever, abdominal pain, and dyspnea. Her past medical history was significant; she had hypertension and rheumatic heart disease with severe mitral insufficiency developed some years after a commissurotomy in 1967. In June 2000, the patient had received a 29-mm (diameter) Omnicarbon metallic mitral valve replacement. No other underlying disease was found. Her medical history revealed no predisposing event, such as dental procedures or intravenous injections. On physical examination, her blood pressure was 110/60 mm Hg, her pulse rate was 93 beats per min, and her body temperature was 37.7°C. Cardiac examination revealed pansystolic murmur. She also showed diminished breathing sounds in both lungs and hepatomegaly. Laboratory tests showed a hematocrit of 27%, hemoglobin concentration of 9.7 g/dl, leukocyte count of 6,130 l, platelet count of 127,000 l, serum creatinine level of 1.5 mg/dl, C-reactive protein level of 85 mg/liter, erythrocyte sedimentation rate of 117 mm/h, and lactic dehydrogenase level of 1,110 UI/liter. Chest radiography revealed a greatly increased cardiothoracic ratio and bilateral interstitial infiltrates, while the electrocardiogram showed rapid atrial fibrillation. The transthoracic echocardiogram demonstrated suspicious vegetations on the prosthetic mitral valve and severe mitral regurgitation. A transesophageal echocardiogram was done, and it showed multiple vegetations on the anterior leaflet of the mitral annulus as well as severe periprosthetic mitral regurgitation (Fig. 1). Three blood cultures were drawn. The patient began an intravenous regimen of vancomycin (1 g every 12 h), gentamicin (60 mg every 8 h), and rifampin (300 mg every 8 h) before the sensitivity report.Emergency mitral valve replacement surgery became necessary 7 days after she was admitted to the hospital because of septic shock. A vegetation on the anterior leaflet was removed and sent for culture, and a new 29-mm (diameter) Omnicarbon mechanical valve was inserted.A few days after surgery, all three blood cultures (ESP culture system II; Trek Diagnostic Systems, Inc.) yielded a gramnegative bacillus. The cardiac vegetation was cultured in sheep blood agar, chocolate agar, and MacConkey agar, the plates were incubated at 37°C in an atmosphere enriched with 5% CO 2 , and a pure growth of gram-negative bacillus was obtained after 48 h of incubation. The biochemical profile determined by the API 20NE strips (BioMérieux, Marcy l'Etoile, France) gave excellent identification of Ochrobactrum anthropi (API 20NE number 0244767). The organism...