Diphtheria bacteria. Coloured Transmission Elec- tron Micrograph (TEM) of three Corynebacterium diphtheriae bacteria, cause of diphtheria. They are Gram-positive rod-shaped bacilli bacteria; sectioned through their cell contents are seen. Corynebacterium diphtheriae is generally located in the human throat, but may affect other mucous membranes and the skin. It may cause constriction in the throat passage impeding normal breathing, sore throat and fever. The multiplying bacteria release toxins into the blood that may damage the heart and nerves. Treatment is with an antitoxin, and use of penicillin drugs. Vaccination produces immunity. Magnification: x6500 at 5x7cm size.