<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 colliBacillus fragilisStreptococcus viridansPseudomonas aerogenosa  <response>: The most common bacteria linked to ascending acute cholangitis is Escherichia coli25-50,followed by other gram negative bacilli like Klebsiella15-20,proteus and pseudomonas.Among gram positive,enterococcus is common10-20and anaerobes like Clostridium. Reference:SRBs manual of surgery,5th edition,page no:643 