Involvement of Kytococcus schroeteri in a case of prosthetic valve endocarditis

We report a fourth case of prosthetic valve endocarditis caused by the newly described micrococcal species: Kytococcus schroeteri. A 38-year old male was admitted to our hospital with suspected prosthetic valve endocarditis. In three blood cultures and in the prosthetic heart valve culture grew the same type of microrganism, initially identified as Micrococcus luteus. Presuntive assignment to the genus Kytococcus was suggested by the arginina dihydrolase activity and by the resistence to penicillin, oxacillin and methicillin, characteristics which are not shared by other micrococci. Further biochemical tests confirmed that the isolates belonged to the genus Kytococcus (negative reaction for oxydase, esculin and urease, positive for catalase and arginine dihydrolase) species schroeteri (alpha-glucosidase positive). The patient was treated with vancomycin, gentamicin and rifampicin. After the valve replacement, on the 20th day of hospitalization, the patient’s biological parameters returned to normal values, and after one mounth the resolution of the disease was completed. The diagnosis of four cases by K. schroeteri endocarditis, described within a short period of time (2003-2006), might indicate a specific pathogenicity of this new species. In case of endocarditis diagnosis, the suspect of the genus Kytococcus involvement should be considered each time the aerobic Gram positive cocci, with arginina dihidrolase activiy and the resistence to penicillin, oxacillin and methicillin, are isolated by significative biological samples.