E. coli 0157
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An infection of variable severity
characterized by diarrhea (often bloody) and abdominal
cramps. Illness may be complicated by hemolytic uremic
syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP);
asymptomatic infections also may occur and the organism may
cause extraintestinal infections.
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| Escherichia coli O157:H7 is a leading cause of foodborne illness. Based on a 1999 estimate, 73,000 cases of infection and 61 deaths occur in the United States each year. |
| Undercooked or raw hamburger (ground beef) has been implicated in many of the documented outbreaks, however E. coli O157:H7 outbreaks have implicated alfalfa sprouts, unpasteurized fruit juices, dry-cured salami, lettuce, game meat, and cheese curds. Raw milk was the vehicle in a school outbreak in Canada. |
| Young children typically shed the organism in their feces for a week or two after their illness resolves. Older children and adults rarely carry the organism without symptoms. |
| Currently, there are four classes of enterovirulent E. coli that cause gastroenteritis in humans. Among these is the enterohemorrhagic (EHEC) strain designated E. coli O157:H7. E. coli is a normal inhabitant of the intestines of all animals, including humans. When aerobic culture methods are used, E. coli is the dominant species found in feces. A minority of E. coli strains are capable of causing human illness. E. coli serotype O157:H7 is a rare variety of E. coli that produces large quantities of one or more related, potent toxins that cause severe damage to the lining of the intestine. These toxins [verotoxin (VT), shiga-like toxin] are closely related or identical to the toxin produced by Shigella dysenteriae. |
| HUS E coli 0157 NEJM 2000 |
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Isolation |
| No special precautions are required. Healthcare workers use Standard and Enteric Precautions. |
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Quarantine |
| Quarantine of case contacts not required. |
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Treatment |
| Most people recover
without antibiotics or other specific treatment within 5 to 10
days. Antibiotics should not be used to treat this infection.
There is no evidence that antibiotics improve the course of
disease, and it is thought that treatment with some antibiotics
could lead to kidney complications. Antidiarrheal agents, such
as loperamide (Imodium®), should also be avoided. E. coli O157:H7 infection can cause hemolytic uremic syndrome (HUS). Blood transfusions and kidney dialysis are often required. With intensive care, the death rate for hemolytic uremic syndrome is 3%-5%. |
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"Boil it, cook it, peel it, or forget it" |
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Prevention |
| Ground beef should
be cooked until a thermometer inserted into several parts of the
patty reads at least 160º F.
Contaminated meat looks and smells normal. Consumers can prevent E. coli O157:H7 infection by thoroughly cooking ground beef, avoiding unpasteurized milk, and by washing hands carefully before preparing or eating food. Fruits and vegetables should be washed well, but washing may not remove all contamination. Wash fruits and vegetables under running water, especially those that will not be cooked. Be aware that bacteria are sticky, so even thorough washing may not remove all contamination. Remove the outer leaves of leafy vegetables. |