[A case of infective endocarditis in which a new vegetation appeared on a different site during chemotherapy].

42-year-old man, who had been febrile for about a month, was admitted to our hospital. Laboratory testing showed leukocytosis and high titer of CRP. Streptococcus sanguis II was detected in his blood culture. According to the echocardiogram, he had a vegetation on the anterior mitral leaflet, so he was diagnosed as having infective endocarditis. Antibiotic susceptibility test using the disc method showed (3+) response to penicillin G. After intravenous administration of 20 million units of penicillin G for 3 weeks, a new vegetation appeared on the posterior mitral leaflet although the one on the anterior mitral leaflet had disappeared. Imipenem/cilastatin was administered until the acute phase reactants became negative. But the vegetation did not disappear, so he had vegetectomy. This is the first case report of infective endocarditis in which a new vegetation appeared on a different site despite the disappearance of the first lesion during chemotherapy.