This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'All of the following causes biliary obstruction except: \nSelect and explain. \nA. Clonorchis, B. Ascaris, C. Ancylostoma duodenale, D. Fasciola', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) Ankylostoma duodenale Hepatobiliary Parasitism Common in Southern China Biliary tract is infestated by adult helminths or their ova Causes: (a) Trematodes (Liver or biliary flukes) MC Clonorchis sinensis Opisthorchis viverrini or 0. felineus Fasciola hepatica (b) Nematode (Ascaris lumbricoides by intraductal migration of adult worm) (c) Cestodes (Echinococcus by intrabiliary rupture of hydatid cyst) Clinical Features: Chronic/recurrent pyogenic cholangitis +- multiple hepatic abscess Ductal stones Biliary obstruction Diagnosis: Cholangiography Characteristic ova on stool examination Treatment: If obstruction is present, TOC is laparotomy under antibiotic coverage with common duct exploration and biliary drainage procedure. Helminths causing obstructive jaundice are: Ascaris, Clonorchis, Fasciola, Echinococcus.', 'role': 'assistant'}]