by Dr.James Hilton
What is E. Coli 0157:117 ?
E. Coli 0157:147 has emerged as a major cause of both sporadic cases and outbreak cases of diarrhea in North America.
The first report described outbreaks of gastroenteritis that were associated with the consumption of undercooked ground beef from a
chain of fast food restaurants.
Since this report, several studies have shown that infection with E. Coli 0157:147 is responsible for most cases of Hemolytic-Uremic
Syndrome, which is a major cause of renal failure in children. In addition, we now know E. Coli 0157:147 is a major cause of bloody
and non-bloody diarrhea in children.
In the United States E. Coli 0157:147 is estimated to cause more than 20,000 infections and as many as 250 deaths per year.
The combination of letters and numbers in the specification refers to specific markers found on its surface and distinguishes it from other types of E. Coli.
Incidence
A prospective population-based study in Seattle in 1985 and 1986 reported an incidence of 8 infections per 100,000 children per year.
The peak incidence is from June to September.
How is E. Coli 0157:117 spread ?
The majority of outbreaks have resulted from the transmission of the organism through the consumption of beef, most commonly
undercooked ground beef.
E. Coli 0157:147 is present in the intestines in approximately 1 percent of healthy cattle.
Beef can be contaminated during slaughter and in the process of grinding the beef.
If the meat is incompletely cooked, the bacteria can survive and be ingested.
Since ground beef may include meat from many carcasses, a small number of infected animals can contaminate a large supply of
ground beef
Other modes of documented transmissions include: transmission from unchlorinated water, swimming in a fecally contaminated lake
and secondary transmission from person to person.
One study reported a secondary attack rate of 22 percent among day care centres. Therefore, handwashing is imperative.
E. Coli 0157:147 is also present on cow's udders and can thus be found in unpasturized milk.
What Kind of illness Does E. Coli 0157:117 Cause ?
This organism can cause asymptomatic infection, non-bloody diarrhea, bloody diarrhea, 1Hemolytic-Uremic Syndrome,
thrombocytopenic purpura and death.
Hemolytic-Uremic Syndrome occurs most commonly in children under the age of 5 years or in the elderly. This suggests immunity
plays a role but this has not been proven.
2 - 7% of E. Coli 0157:117 infection leads to this complication.
How is E. Coli 0157:117 Diagnosed ?
This infection is diagnosed by detecting the bacterium in stool.
If you suspect this infection, it is important to request the laboratory test the stool specimen on Sorbitol-MacConkey Agar (SMAC) for
this organism.
All persons who suddenly have bloody diarrhea should have their stool tested for E. Coli 0157:147.
How is the illnessTreated?
No specific therapy has proved effective in patients with E. Coli 0157:147 infection. Antimotility agents are contraindicated in patients
with bloody diarrhea.
Some studies have shown that Hemolytic-Uremic syndrome may be more likely to develop in patients treated with an antibiotics such
as trimethoprim-sulfa.
Hemolytic-Uremic syndrome is treated in an intensive core setting.
Dialysis and blood transfusions are often required.
With intensive care the death rate for Hemolytic-Uremic syndrome is 3 -5%
What are the long-term consequences of Infection ?
Persons who only have diarrhea usually recover completely in about one week with no obvious sequelae.
Hemolytic-Uremic syndrome occurs in about 6 percent of patients and is usually diagnosed 2 -14 days after the onset of diarrhea.
Probably the most common cause of acute renal failure in children, the Hemolytic-Uremic syndrome is characterized by
microangiopathic hemolytic anemia, thrombocytopenia, renal failure and central nervous system manifestations.
This syndrome is most likely to occur in the young and the elderly. The neurologic complications which occur in 25% of the patients
included seizures, coma and hemiparesis.
Approximately 50% of the patients require dialysis. The mortality rate is 3 to 5%
5% of patients who survive HUS have severe sequelae such as hypertension, chronic renal failure or permanent neurologic injury.
Prevention of E. Coli 0157:117
- cook all ground beef thoroughly
- do not consume unpasteurized milk
- exclusion of infected children from day care centres until 2 negative stool cultures are obtained
- supervised hand washing in day care
- by making E. Coli 0157:147 a reportable disease