Kytococcus schroeteri Endocarditis

Kytococcus schroeteri Endocarditis To the Editor: Becker et al. recently reported the probable implication of Kytococcus schroeteri in a case of acute prosthetic valve endocarditis, on the basis of its recovery from blood cultures drawn at the time of infection (1). K. schroeteri was only characterized on that occasion and is a new micrococcal species resistant to peni-cillins (2). Here, we report the isolation of this organism from prosthetic valve vegetations in a patient who had undergone aortic valve replacement 3 years earlier. The 73-year-old man was admitted with fever (38.8°C) and shortness of breath, which had both increased gradually over the previous 2 months. He had no recent history of intravenous drug administration or catheterization. Laboratory findings showed a leukocyte count of 12 x 10 9 /L (90% neutrophils) and a raised C-reactive protein level. Transeso-phageal echocardiogram revealed several small vegetations on the Carpentier-Edwards aortic bioprosthe-sis and a voluminous perivalvular abscess. Four sets of blood cultures were drawn before antimicrobial therapy was initiated. Intravenous vancomycin (2 g twice a day) and gentamicin (240 mg/d) were started empirically. The prosthet-ic material was replaced promptly and the abscess was debrided extensively. Vegetations from the resected material showed numerous polymorphonuclear neutrophils and gram-positive cocci on microscopic examination. Oral rifampicin (600 mg twice a day) was added to the initial regimen. The postoperative course was uneventful except for cutaneous intolerance to vancomycin, which was replaced with teicoplanin. The physical condition of the patient improved steadily. Gentamicin and rifampicin were discontinued after 3 weeks. Eight months after completion of the 6-week treatment, the patient had no clinical or biologic evidence of infection , although moderate aortic incompetence persisted. All blood cultures drawn on admission grew gram-positive cocci after 72 hours and subcultures on Trypticase soy agar yielded convex, muddy-yellow colonies of heterogeneous sizes. The vegetations, pus samples of the abscess, and prosthetic valve cultures grew the same type of colonies. All isolates displayed identical biotype and antimicrobial susceptibility and were considered as a single strain. The causative organism (designated ROG140) was initially identified as Micrococcus sp. based on the morphologic features, resistance to nitrofurantoin, and inability to grow anaerobically. Assignment to the genus Kytococcus was suggested by the arginine dihydrolase activity and resistance to oxacillin, 2 characteristics that are not shared by other micro-cocci (3). The definitive K. schroeteri identification was provided by analysis of the fatty acid content, which was similar to that …