Clostriium difficile (pronounced /klɒsˈtrɪdiəm dɪˈfɪsɪli/, also known as CDF/cdf', or 'C. diff') is a species of bacteria of the genus Clostridium which are Gram-positive, anaerobic, spore-forming rods (bacillus).C. difficile is the most significant cause of pseudomembranous colitis, a severe infection of the colon, often after normal gut flora is eradicated by the use of antibiotics. Treatment is performed by stopping any antibiotics and commencing specific anticlostridial antibiotics, e.g. metronidazole.