Actually I think what you mean to say is this: Clostridium difficile infection can cause pseudomembraneous colitis which can lead, in extreme cases, to toxic megacolon. The C. diff infection often comes about as a result of taking a broad-spectrum antibiotic (such as Clinamycin) which destroys the normal gut flora, enabling C. diff, if present or introduced, to completely take over. Normally the beneficial species of microorganisms in the gut flora can overcome C. diff.