Image:Esch coli.jpg

This scanning electron micrograph (SEM) depicts a number of rod-shaped Escherichia coli bacteria, some of which have formed colonial groupings, while others have remained isolated as single cells; Magnification 3607x.

Escherichia coli is a Gram-negative bacterium that normally colonizes the digestive tract of most warm-blooded animals, including human beings. E. coli are facultative in nature, which means that they can adapt to their environments, switching between aerobic, and anaerobic metabolic growth depending environmental stresses. One strain of E. coli, O157:H7, causes an estimated 73,000 cases of infection, and 61 deaths in the United States each year. Infection often leads to bloody diarrhea, and occasionally to kidney failure. Most illness has been associated with eating undercooked, contaminated ground beef. Person-to-person contact in families and child care centers is also an important mode of transmission. Infection can also occur after drinking raw milk and after swimming in or drinking sewage-contaminated water.

Image source: Centers for Disease Control and Prevention Publich Health Image Library.

This image is a work of the Centers for Disease Control and Prevention, part of the United States Department of Health and Human Services, taken or made during the course of an employee's official duties. As a work of the U.S. federal government, the image is in the public domain.

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