E. coli Infection - Exams and Tests

Exams and Tests

The medical evaluation for diarrhea that may be caused by E. coli O157:H7 bacteria usually starts with a physical examination and a medical history.

During the medical history, a health professional will ask questions about your symptoms, such as:

• When did diarrhea begin, how long has it lasted, and how frequent are bowel movements?
• Is there blood in the diarrhea? If so, how much?
• Have you had chills or a fever?
• Have you had any abdominal cramps, nausea, or vomiting?
• Do you feel tired or irritable?
• Have you fainted or felt lightheaded?

Infection with E. coli is easily mistaken for other conditions with similar symptoms, such as other infectious diseases.

A health professional may suspect you have E. coli infection if you have been exposed to the bacteria. During the medical history, a health professional may ask if you have:

• Been in a day care center, school, nursing home, or other adult care institution.
• Eaten recently at a restaurant.
• Consumed any undercooked meat, unpasteurized milk or other dairy products, or unpasteurized juice.
• Had contact with anyone with recent or ongoing diarrhea.
• Traveled recently.
• Used antibiotics recently.

During the physical examination, a health professional will usually:

• Take your temperature.
• Take your blood pressure and determine your pulse rate.
• Look at your skin color to see whether you are unusually pale.
• Check your stomach for tenderness.
• Perform a rectal exam to find out whether you have blood in your stool.

Health professionals who suspect E. coli infection will order a type of stool culture that detects strains of E. coli. Because the bacteria can leave the body in only a few days, the sample should be obtained as soon as possible after symptoms appear.

Other tests are sometimes used when the diagnosis is unclear, but these are not yet widely available.

If a child or older adult is diagnosed with E. coli infection, he or she may be watched for development of severe blood or kidney problems. Monitoring requires blood and urine tests to measure essential elements of blood and body fluids.