Color enhanced transmission electron micrograph (TEM) of a Listeria monocytogenes bacterium. L. monocytogenes causes listeriosis, a form of food poisoning that results in abdominal pains, fever and diarrhea. Severe infections can be fatal. It is widespread in the environment, particularly in soil, and is contracted from contaminated foodstuffs. Sources of human infection include milk, soft cheese and improperly cooked meat. Treatment is with antibiotic drugs. Magnification 20,000x at 10 cm.