Shiga toxin-producing E. coli (STEC)

Question 1

TRUE or FALSE: Shiga toxin-producing E. coli (STEC), can cause severe foodborne disease

Answer 1

TRUE

Question 2

How is STEC transmitted to humans?

Answer 2

primarily through consumption of contaminated foods, such as raw or undercooked ground meat products, raw milk, and contaminated raw vegetables and sprouts.

Question 3

Describe the toxins produced by STEC

Answer 3

STEC produces toxins, known as Shiga-toxins because of their similarity to the toxins produced by Shigella dysenteriae.

Question 4

Describes conditions that promote grwoth of STEC

Answer 4

• STEC can grow in temperatures ranging from 7 °C to 50 °C, with an optimum temperature of 37 °C.
• Some STEC can grow in acidic foods, down to a pH of 4.4, and in foods with a minimum water activity (aW) of 0.95.

Question 5

How is STEC destroyed?

Answer 5

• STEC is destroyed by thorough cooking of foods until all parts reach a temperature of 70 °C or higher.
• E. coli O157:H7 is the most important STEC serotype in relation to public health; however, other serotypes have frequently been involved in sporadic cases and outbreaks.

Question 6

What are the symptoms of diseases caused by STEC?

Answer 6

• Abdominal cramps
• Diarrhoea that may in some cases progress to bloody diarrhoea (haemorrhagic colitis)
• Fever and vomiting may also occur

Question 7

What is the incubation period of STEC?

Answer 7

The incubation period can range from 3 to 8 days, with a median of 3 to 4 days.

Question 8

Do most patients recover from STEC?

Answer 8

Most patients recover within 10 days, but in a small proportion of patients (particularly young children and the elderly), the infection may lead to a life-threatening disease, such as haemolytic uraemic syndrome (HUS). HUS is characterized by acute renal failure, haemolytic anaemia and thrombocytopenia (low blood platelets).

Question 9

TRUE or FALSE: Antibiotics are part of the treatment of patients with STEC disease

Answer 9

FALSE

Question 10

What are the main resovoirs for STEC serotype O157:H7?

Answer 10

The reservoir of this pathogen appears to be mainly cattle. In addition, other ruminants such as sheep, goats, deer are considered significant reservoirs, while other mammals (such as pigs, horses, rabbits, dogs, and cats) and birds (such as chickens and turkeys) have been found infected.

Question 11

Give examples of foods implicated in outbreaks of E. coli O157:H7

Answer 11

• undercooked hamburgers
• dried cured salami
• unpasteurized fresh-pressed apple cider
• yogurt
• cheese made from raw milk

Question 12

An increasing number of outbreaks are associated with the consumption of which fruits and vegetables

Answer 12

• sprouts
• spinach
• lettuce
• coleslaw
• salad

Contamination may be due to contact with faeces from domestic or wild animals at some stage during cultivation or handling

Question 13

Which bodies of water have STEC has also been isolated from?

Answer 13

• Ponds and streams
• wells and water troughs
• STEC has been found to survive for months in manure and water-trough sediments.

Waterborne transmission has been reported, both from contaminated drinking-water and from recreational waters.

Question 14

Explan prevention of STEC infections

Answer 14

The prevention of infection requires control measures at all stages of the food chain, from agricultural production on the farm to processing, manufacturing and preparation of foods in both commercial establishments and household kitchens.

• Good hygienic slaughtering practices reduce contamination of carcasses by faeces
• Education in hygienic handling of foods for workers at farms, abattoirs and those involved in the food production is essential to keep microbiological contamination to a minimum.
• The only effective method of eliminating STEC from foods is to introduce a bactericidal treatment, such as heating (for example, cooking or pasteurization) or irradiation.
• Regular hand washing, particularly before food preparation or consumption and after toilet contact