Clostridium difficile bacteria. Coloured scanning electron micrograph (SEM) of dividing (reproducing) C. difficile bacteria (green) and dead bacteria cells (pink). These rod-shaped bacteria cause pseudomembranous colitis, one of the most common hospital-acquired infections, and antibiotic-associated diarrhoea. Infection can be fatal. Treatment is with antibiotic drugs, although this bacterium has become increasingly resistant to the use of antibiotics. Magnification: x8,065 when printed 10 centimetres wide.