<prompt> A patient of post-cholecystectomy biliary stricture has undergone an ERCP three days ago. Following this, she has developed acute cholangitis. The most likely organism isEscherichia coliBacillus fragilisStreptococcus viridansPseudomonas aeruginosa  <response>: Cholangitis Ascending bacterial infection of the biliary ductal system with obstruction MC cause of acute cholangitis is choledocholithiasis MC organisms present in the bile in patients with cholangitis : E.coli, Klebsiella pneumoniae, streptococcus faecalis Bacteroides fragilis Ref:Sabiston 20th edition Pgno :1507 