Atlas of foodborne infections
transmitted by contaminated food and water

Atlas of Patogens Contents Information sources Glossary Administration

Escherichia coli (E.coli)

CZ: E.coli (čti é kólí, rod ešerychyja)
EN: E.coli

Occurrence:
Meat and Meat Products
Milk and Milk Products
Fruits and Vegetables
Water and Beverages


Category:
Bacteria


Foodborne Disease:
Untitled document


Escherichia coli
O157:H7 - bloody diarrhoea, and occasionally to kidney failure


Description:
Untitled document

Most illness has been associated with eating undercooked, contaminated ground beef. Person-to-person contact in families and childcare 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.

E. coli O157:H7, one of hundreds of strains of the bacterium Escherichia coli, is an emerging cause of food-borne illness. Although most strains are harmless and live in the intestines of healthy humans and animals, this strain produces a powerful toxin and can cause severe illness. The organism can be found on a small number of cattle farms and can live in the intestines of healthy cattle.

Meat can become contaminated during slaughter, and organisms can be thoroughly mixed into beef when it is ground. Bacteria present on the cow’s udders or on equipment may get into raw milk. Bacteria in diarrhoeal stools of infected persons can be passed from one person to another if hygiene or hand washing habits is inadequate. Contaminated meat looks and smells normal.

Young children typically shed the organism in their faeces for a week or two after their illness resolves. Older children rarely carry the organism without symptoms. Infection with E. coli O157:H7 is diagnosed by detecting the bacterium in the stool.

E. coli O157:H7 infection often causes severe bloody diarrhoea and abdominal cramps; sometimes the infection causes non-bloody diarrhoea or no symptoms. Usually little or no fever is present, and the illness resolves in 5 to 10 days. In some persons, the infection can also cause a complication called haemolytic uremic syndrome, in which the red blood cells are destroyed and the kidneys fail. Most persons recover without antibiotics or other specific treatment in 5-10 days.

Escherichia coli is part of the normal flora of the intestinal tract of humans and warm-blooded animals. Its presence in food or water is generally an indication of fecal contamination. Many strains are harmless; however, some cause gastroenteritis or more serious forms of illness. Pathogenic strains are grouped as follows:
•    enteroaggregative (EAggEC)
•    enteropathogenic (EPEC)
•    enteroinvasive (EIEC)
•    enterotoxigenic (ETEC)
•    verocytotoxin-producing E. coli (VTEC), also called shiga-toxin-producing E. coli (STEC). Enterohem- orrhagic E. coli (EHEC), which causes HUS, is a subset of VTEC.

In nonindustrialized countries, diarrhea caused by pathogenic E. coli is a major cause of morbidity and mortality. In industrialized countries, where hygiene standards are generally higher, little diarrheal illness has been associated with E. coli other than traveler's diarrhea in which ETEC strains play a role. VTEC, however, is of considerable concern in the developed world, due to the severity of the illness.

The organism is not particularly heat resistant and is easily killed by cooking, but the low infective dose means that foods must be cooked thoroughly and be protected after cooking from cross-contamination with raw foods. Foods of bovine origin, such as undercooked beef burgers or unpasteurized milk, have been implicated in a number of VTEC outbreaks.


Pictures:

E.coli
Source: A magnified view of E.coli bacteria - scan microscopy
E.coli
Source: A magnified view of E.coli bacteria - scan microscopy
E.coli
Source: A magnified view of E.coli bacteria - scan microscopy (detail)
E.coli
Source: E.coli in minced meat
E.coli
Source: E.coli under the microspcope (colored)
E.coli
Source: Groundbeef - a main source of bacterial infection
E.coli
Source: microbiological cultivation

<<< Back