Escherichia coli (E. coli) Food Poisoning
Escherichia coli O157:H7, more commonly referred to as E. coli, is an emerging cause of foodborne illness. E. coli O157:H7 was first recognized as a cause of enteric disease in 1982, following an outbreak of severe bloody diarrhea. It was later traced to contaminated hamburgers. The disease is typically characterized by severe diarrhea (often bloody) and abdominal cramps.
The U.S. Centers for Disease Control and Prevention (CDC) estimates that E. coli affects 73,000 people in the United States each year, causing 2,000 hospitalizations and 61 deaths.
E. coli O157:H7 is just one of hundreds of strains of the bacterium Escherichia coli. While most strains of E.coli are harmless and live in the intestines of healthy humans and animals, E. coliO157:H7 produces a powerful toxin and can cause severe illness. Children and the elderly are at greatest risk for complications resulting from E. coli O157:H7 infection.
What are the symptoms of E. coli foodborne illness?
Initial symptoms of E.coli O157:H7 infection include severe abdominal cramps and watery diarrhea. The diarrhea may become bloody and can lead to dehydration. Sometimes there are no symptoms at all. There is usually little or no fever. Symptoms usually resolve in 5-10 days.
Hemolytic Uremic Syndrome (HUS), a serious complication of E.coli O157:H7 infection, may occur in about 2%-7% of cases. HUS is characterized by destruction of red blood cells, damage to the lining of blood vessel walls, and in severe cases, kidney failure. Children and the elderly are at greatest risk for developing HUS. HUS is the principal cause of acute kidney failure in children in the United States.
Thrombotic Thrombocytopenic Purpura (TTP) is a clinical syndrome characterized by low blood platelet counts, anemia, and kidney failure. Doctors may refer to adult HUS as TTP due to similar clinical features.
How are E. coli infections caused?
E. coli food poisoning is most often associated with eating undercooked, contaminated ground beef. Since E. coli can be found in the intestines of healthy cattle, meat can become contaminated during slaughter. The bacteria are then thoroughly mixed into the beef while it is being ground and processed. Other sources of infection include the consumption of non-pasteurized milk and juice, sprouts, leafy greens such as lettuce and spinach, and salami; swimming in sewage-contaminated lakes and pools; or drinking inadequately chlorinated water.
Person-to-person contact in families, childcare centers, and nursing homes is also an important mode of transmission. Bacteria in the stools of infected individuals can be passed from one person to another if hygiene or handwashing habits are inadequate.
How is E.coli infection diagnosed and treated?
According to the CDC, infection with E. coli O157:H7 is diagnosed by detecting the bacterium in the stool. Most laboratories that culture stool do not test for E. coli O157:H7, so it is important for your doctor to request that the stool specimen be tested on sorbitol-MacConkey (SMAC) agar for this organism. Anyone who suddenly develops bloody diarrhea should have a stool sample tested for E. coli O157:H7.
The CDC also reports that individuals who have diarrhea as their only symptom usually recover completely. Most people recover without antibiotics or other specific treatment in 5-10 days. There is no evidence that antibiotics improve the course of disease, and it is thought that treatment with some antibiotics may precipitate kidney complications. Antidiarrheal agents, such as loperamide (Imodium), should also be avoided.
Hemolytic Uremic Syndrome (HUS), a life-threatening complication of E.coli O157:H7, is usually treated in an intensive care setting. Blood transfusions and kidney dialysis are often required.
Are there complications with E. coli infections?
Individuals who have diarrhea as their only symptom usually recover completely.
About one-third of people with HUS have abnormal kidney function many years later, and a few require long-term dialysis. Another 8% of people with HUS have other lifelong complications, such as high blood pressure, seizures, blindness, paralysis, and the effects of having part of their bowel removed. With intensive care, the death rate for HUS is 3%-5%.
How can E. coli infections be prevented?
Consumers can prevent E. coli infection by thoroughly cooking ground beef, avoiding non-pasteurized milk and juices, and washing hands with soap and water. Because the organism lives in the intestines of healthy cattle, preventive measures on cattle farms and during meat processing must be taken to avoid contamination
The following precautions can help prevent E. coli infection:
- Cook all ground beef and hamburger thoroughly. Use a digital instant-read meat thermometer to ensure that the thickest part of the meat reads at least 160º F. People who cook ground beef without using a thermometer can decrease their risk of illness by not eating hamburgers that are still pink in the middle, however, using a meat thermometer is still your best protection against E. coli infection.
- If you are served an undercooked hamburger or other ground beef product in a restaurant, send it back for further cooking. You may want to ask for a new bun and a clean plate, too.
- Keep raw meat separate from ready-to-eat foods.
- Keep fruits and vegetables separate from raw meat when grocery shopping. Wash fruits and vegetables thoroughly, especially those that will not be cooked.
- Wash hands, counters, and utensils with soap and hot water after contact with raw meat. Never place cooked hamburgers or ground beef on the unwashed plate that held the raw patties. Wash meat thermometers in between tests of patties that require further cooking.
- Drink only pasteurized milk, juice, or cider.
- Children under 5 years of age, immuno-compromised individuals, and the elderly should avoid eating alfalfa sprouts.
- Drink municipal water that has been treated with chlorine or other effective disinfectants.
- Avoid swallowing lake or pool water while swimming.
- Make sure that people with diarrhea, especially children, wash their hands carefully with soap and water after bowel movements to reduce the risk of spreading infection, and that individuals wash hands after changing soiled diapers. Anyone with a diarrheal illness should avoid swimming in public pools or lakes, sharing baths with others, or preparing food for others.