<prompt> In a case of diarrhea with histopathological evidence of intestinal mucosal clefts studded with copious thick secretions and inflammatory cells is characteristic of pseudomembranous colitis. The likely cause is?Ischemic colitisClostridium defficileE. coliAll of1 the above  <response>: Ans. b Clostridium defficile. Ref. Harrisons, Internal medicine, 16th ed., 760PSEUDOMEMBRANOUS OR CLOSTRIDIUM COLITIS Inflammation of colon by C. defficile and its toxin, A and B Cytotoxic and enterotoxic effect Most common symptom--watery diarrhea and acute abdomen. Diagnosis made by stool assay of cytotoxin, takes 48 hours. Elderly are at higher risk than young. Drugs causing it is ampicillin, vancomycin,etc HPE:Mildfocal necrosis of surface epithelial cells in glandular crypts with neutrophilic infiltration and fibrin plugging of capillaries in lamina propria and copious thick mucus hypersecretions in adjacent crypts.ModerateCrypt abscessesSevereNecrosis and denudation of mucosa with thrombosis of submucosal venules. Accordion sign is diagnostic on CECT. Treatment:- Stop the culprit drug- Metronidazole DOC and vancomycin. Q 