Tiêu đề 0000-MRCP Sep 2020 (ANSWER KEY).pdf ✅

S. sanguinis exists as part of the normal mouth flora, although in circumstances of poor oral hygiene, haematogenous spread may occur, leading to endocarditis particularly affecting the aortic and mitral valves. An orthopantomogram is the most appropriate investigation because it may identify a dental abscess as the underlying cause of haematogenous bacterial spread. A Abdominal computerised tomography (CT) S. sanguinis exists as part of the normal mouth flora; it is not a gastrointestinal cause of bacterial endocarditis. Hence abdominal CT is of no value as a next investigation. Abdominal CT may be of value in patients with Streptococcus gallolyticus infection who are unfit for a colonoscopy, given that underlying colon cancer is a well-recognised cause of S. gallolyticus endocarditis. B Colonoscopy Colonoscopy is the investigation of choice for S. gallolyticus endocarditis. Case series suggest that when this bacterium is identified as a cause of endocarditis, colon cancer is found in up to 65% of cases. Colonoscopy is the most sensitive investigation to identify an underlying colonic neoplasm. Where patients are unable to undergo the procedure, a CT colonoscopy is the best alternative. C Endoscopic retrograde cholangiopancreatography (ERCP) Where colonoscopy does not reveal an underlying neoplasm in cases where S. gallolyticus endocarditisisidentified, imaging of the biliary tree should take place because the biliary tree is the next commonest source of the bacterium after the colon. Magnetic resonance cholangiopancreatography (MRCP) is, however, preferred to ERCP initially, because it is non- invasive. E Upper gastrointestinal (GI) endoscopy Upper GI tract abnormalities are not a recognised cause of S. sanguinis bacterial infection. An endoscopy is therefore not of value here. GI instrumentation itself may be a cause of endocarditis in patients with pre-existing valve dysfunction.