[A case of Streptococcus gallolyticus subsp. gallolyticus infective endocarditis with colon adenoma]

An 80-year-old Japanese man had a fall presented with a 3-week history of right lumbago exacerbated by body movement as well as a 1-week history of anomalous behavior and appetite loss. He visited our hospital complaining of difficulty in standing up. He had a history of mitral prolapse due to an unknown rupture of the chordae tendineae 3 years earlier, which resulted in moderate mitral valve regurgitation and atrial fibrillation. Upon visiting the hospital, he had petechial hemorrhage and jaundice of the conjunctiva, a systolic murmur (Levine II/VI) at the apex and 4th interspace of the left sternal border, and a positive right straight leg raising test result. Moderate bilirubinemia and disseminated intravascular coagulation which were considered to have been produced secondarily were observed. Infective endocarditis was suspected, and 3 sets of blood culture were extracted. The patient was admitted on the same day. Blood cultures were positive for Streptococcus gallolyticus subsp. gallolyticus (6/6) on the following day. Transesophagela echocardiography was carried out on the same day, and vegetation with a diameter of 4mm was observed in the anterior mitral leaflet; the patient was subsequently diagnosed as having infective endocarditis. Colonic endoscopy was performed after hospitalization. Twelve colonic adenomata were found, and endoscopic mucosal resection was performed on one polyp. The bacterium found in the culture was classified as Streptococcus bovis type I, which causes infective endocarditis and bacteremia. Furthermore, this bacteria is a relatively rare causative organism of infective endocarditis. Tolerance to macrolide and tetracycline are reported in the literature. Moreover, the cell wall of this bacterium may have low pathogenicity as well as cause chronic inflammation in the large intestine mucous membrane, colonic polyps, and colorectal cancer. Several colonic adenomata and a partial shift to a malignant pathology were observed in this case. When this bacterium is detected, searching for a pathological change in the large intestine is believed to be indispensable.