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Food-Info.net> Topics > Food Safety > Bacteria > Overview of food-borne bacteria

Escherichia coli EPEC

General characteristics

E. coli are Gram-negative, rod-shaped bacteria belonging the family Enterobacteriaceae

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 faeces. Normally E. coli serves a useful function in the body by suppressing the growth of harmful bacterial species and by synthesizing appreciable amounts of vitamins. A minority of E. coli strains are capable of causing human illness by several different mechanisms. Among these are the enteropathogenic (EPEC) strains. EPEC are defined as E. coli belonging to serogroups epidemiologically implicated as pathogens but whose virulence mechanism is unrelated to the excretion of typical E. coli enterotoxins.

Disease symptoms

Infantile diarrhoea is the name of the disease usually associated with EPEC.

EPEC cause either watery or bloody diarrhoea, the former associated with the attachment to, and physical alteration of, the integrity of the intestine. Bloody diarrhoea is associated with attachment and an acute tissue-destructive process, perhaps caused by a toxin similar to that of Shigella dysenteriae , also called verotoxin. In most of these strains the shiga-like toxin is cell-associated rather than excreted.

Infective dose -- EPEC are highly infectious for infants and the dose is presumably very low. In the few documented cases of adult diseases, the dose is presumably similar to other colonizers (greater than 10 6 total dose).

Diagnosis

The distinction of EPEC from other groups of pathogenic E. coli isolated from patients' stools involves serological and cell culture assays. Serotyping, although useful, is not strict for EPEC.

Associated foods

Common foods implicated in EPEC outbreaks are raw beef and chicken, although any food exposed to faecal contamination is strongly suspect.

Prevention

Enterobacteria (incl. E.coli ) are heat-sensitive and will be killed by thorough heating (over 70 °C). Raw or undercooked foods and cross-contamination, when cooked material comes into contact with raw produce or contaminated materials (cutting boards), are the main causes of infection. Proper cooking and hygienic food handling thus can prevent enterobacterial infections to a large extend.

Risk populations

EPEC outbreaks most often affect infants, especially those that are bottle fed, suggesting that contaminated water is often used to rehydrate infant formulae in underdeveloped countries.

Sources:

The bad bug book : http://www.cfsan.fda.gov/~mow/intro.html

 



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