Most often, pseudomembranous colitis develops under the influence of prolonged use of antibiotics ampicillin, lincomycin, clindamycin, cephalosporins, less often penicillin, erythromycin, levomycetin, tetracycline. Clostridium difficile is a spore-forming gram-positive anaerobic rod that is capable of producing two kinds of exotoxins of toxin A and toxin B. There are four main reasons for the development of pseudomembranous colitis associated with C. Difficile.