<prompt> Crohns disease may be caused by which one of the following infectious agents:Clostridium difficleMycobacterium paratuberculosisCytomegalo virus CMVMycoplasma  <response>: Answer is A Clostridium Difficle A possible infectious etiology includes clostridium difficle and Mparatuberculosis amongst the options provided. Clostridium difficle is the single best answer of choice when based on Harrisons 17th edition. Role of infections in Inflammatory bowel disease Infectious etiology Infection with multiple pathogens may initiate inflammatory bowel disease IBD by triggering an inflammatory response that the mucosal immune system may fail to control Agents According to Harrisons 16th edition Do not mention Clostridium difficle Multiple pathogens Salmonella, Shigella sp. Campylobacter sp. may initiale IBD by triggering an inflammatory response - H16th Anaerobic organisms paicularly Bacterioides species may be responsible for induction of inflammation - H16th Regarding M. Paratuberculosis Three specific agents, M. paratuberculosis paramyxovirus and Helicobacter species have received greatest attention However Mparatuberculosis does not have a confirmed disease association and antimycobacterial agents are not effective in treating CD. Agents according to Harrisons 17th edition Include Clostridium difficle Multiple pathogens Salmonella, Shigella sp, Campylobacter sp, Clostiridium difficle may initiate IBD by triggering an inflammatory response - H17th Anaerobic organisms paicularly Bacterioides and Clostridia species and some aerobic species as Escherechia may be responsible for the induction of inflammation - H1 7th Regarding M. Paratuberculosis Harrisons 17h edition does not mention M Paratuberculosis amongst the list of agents implicated in causing Crohns disease. 