<prompt> Pseudomembranous colitis, all are true except:Toxin A is responsible for clinical manifestationToxin B is responsible for clinical manifestationBlood in stools is a common featureSummit lesions is early histopathological finding  <response>: Ans. is c i.e., Blood in stools is a common feature.Ref: Topleys, 10the, p. 1120-1121Frank blood in stool is not common.ABOUT OTHER OPTIONSOption a and option b Toxin A and B both are responsible for clinical manifestation.Once C. difficile is established in the bowel, disease is a consequence of the production of two large protein toxins, Toxin A and B. Toxin A has both histotoxic and enterotoxic activity and is of major importance in causation of tissue damage and luminal fluid accumulation. Toxin B may independently cause tissue damage.Option dIn the earliest stage of disease summit-lesions, tiny superficial intercryptal erosions, may be found. 