DOD Enterohemorrhagic Escherichia coli/ EHEC

What are the general characteristics of the pathogen (EHEC)

• gram negative

• rod shpaed

• facultative anaerobe

• has flagella (mobile)

facultative anaerobe

can grow using oxygen or without oxygen

what toxin producing this disease

Shiga-toxin producing E. coli (STEC, EHEC) (O157:H7)

what is the emerging cause of food borne illness

Escherichia coli 


is all strains of E coli dangerous

no, Most strains of E. coli are harmless and live in the intestines of healthy humans and animals

• Part of normal flora

why is knowing about E coli important

Estimated 265,000 cases of STEC infection and 61 deaths occur in the United States each year

how does this strain of E. coli cause damage

• Strain produces a “shiga-like” toxin

• Toxin starts by destroying cells which line the large intestine

• Escapes into the blood stream and kills erythrocytes (red blood cells)

• Damages endothelial cells lining the blood vessels

Symptoms/Signs of E. Coli

Abdominal cramps and diarrhea

Progress to bloody diarrhea (hemorrhagic colitis)

Maybe fever and vomiting

Illness resolves in 5 to 10 days

Severe - Haemolytic uraemic syndrome (HUS)

should this disease (e coli) be treated with antibiotics

NO!

Haemolytic uraemic syndrome (HUS)

5-10% of all infections develop into this

• Children under 5 years of age and the elderly are most susceptible to HUS

• red blood cells are destroyed and the kidneys fail

how do u diagnosis e coli

Isolation of E. coli in stool sample grown with Sorbitol MacConkey (SMAC) agar

Selective - inhibit the growth of the Gram positive microbial flora

AND

Differential – cannot utilize sorbitol on plate, therefore, not red

Sorbitol MacConkey (SMAC) agar

• E. coli O157:H7 can ferment sorbitol to make acid

• SMAC turns from pink to yellow due to acids secreted by the bacteria

what is the souce of this strain of e coli

Reservoir of this pathogen appears to be mainly cattle – 50% of feedlot cattle

• organisms can be mixed into beef when it is ground which is why it is important to cook ground beef all the way because the bacteria is everywhere on the meat while on steak it is only on the surface which is why you can eat it rare and stuff

according to the USDA how much of our ground meat is contaminated

90%

sources of e coli

• Dried cured salami

• Unpasteurized fresh-pressed apple cider

• Yogurt, cheese and unpasteurized milk

• Fruits and vegetables (sprouts, lettuce, coleslaw, salad)

• Swimming in or drinking sewage-contaminated water

• Petting zoos

prevention of getting e coli

Cook meat thoroughly and don’t eat undercooked meat – 72˚C (160˚F)

Avoid spreading harmful bacteria in your kitchen (washing hands after touching raw meat)

Drink only pasteurized milk, juice, or cider

Wash fruits and vegetables thoroughly