Back to basics...

Meeting with the microbes

Part 2

This month’s exclusive “autobacteriography” is on Mrs Escherichia coli...

Brace yourself..... you are becoming microscopic..... Honey, I shrunk the readers begins!


PART 2: Escherichia (E.) coli O157


The Food Safety Network (TFSN) Reporter: Good morning Mrs. Coli and welcome to The Food Safety Network.  We are very fortunate to have you here live and exclusive on our website.


Mrs E.coli: The pleasure is all mine. Mr Aureus said that the world is treating him with a bit more respect after your interview with him.

TFSN Reporter: Well that is great news! The fact that the readers and myself are on your microscopic level during this interview make us appreciate your world...with that, lets begin. Tell us your full name...I believe you are just one class of your group...the Enterovirulent E.coli (EEC)?

Mrs E.coli: Yes you’ve done a bit of homework. I am one of the four recognised classes of the EEC group that cause gastroenteritis in humans, the Enterohemorrhagic or EHEC for short. My full name is Escherichia coli O157:H7. But you can call me Mrs H.


TFSN Reporter: Thank you. So you are a gram negative, rod-shaped bacterium, but what are the O and H short for?

Mrs H: I’m very impressed; a good reported always knows their subject. “O” refers to the cell wall (somatic) antigen number and the “H” the flagella antigen number, with which I attach to the corresponding receptors found in the human intestine.

TFSN Reporter: I know that E.coli is a natural inhabitant of the intestines of most animals including ourselves, the humans, and consequently the species found in our faeces?

Mrs H: Yes, that’s correct, but you make us sound so gross! We usually serve quite a useful function in your gut – we suppress harmful bacteria and produce vitamins.


TFSN Reporter: So then why am I worried about are needed...what is the big hype?

Mrs H: Well I am a very rare variety of species as I produce large quantities of toxins that can cause severe damage to the lining of your intestine. My toxins, which I affectionately call verotoxin (VT) are identical to the toxin produced by a Shigella species.

TFSN Reporter: And the other classes?

Mrs H: The other classes include the ETECs or Enterotoxigenic and EPECs or Enteropathogenic, that cause gastroenteritis (specifically diarrhea) and infantile diarrhea. I cause hemorrhagic colitis.....the fancy name for bloody diarrhea.

TFSN Reporter: Step back, you are scary! Explain how you cause disease, specifically food poisoning.


Mrs H: My natural habitat is cattle farms and I can live in the intestines of healthy cows. I can therefore be shed in their faeces and can be spread tohumans.  This occurs if I contaminate meat during slaughter or butchering. I can also be present on cow udders or equipment and can thus contaminate raw milk. I do not change the look, smell or taste of the original food.

TFSN Reporter: Okay, so if we control you at “cow” level you should be stopped from contaminating our foods?

Mrs H: Yes and no...I can also be carried by flies, including the common house fly, to your food.  We have a frequent flyers partnership with Musca domestica Airlines...ha ha ha!

TFSN Reporter: I don’t think your sense of humour is shared by our readers! How exactly do you contaminate our food we eat?

Mrs H: My most frequent route of entry into the human intestine is through your love of under-cooked or raw hamburger (ground/minced) meat.  However, I have successfully contaminated alfalfa sprouts, unpasteurised fruit juices, dry-cured salami, lettuce, game meat and some cheese curds.


TFSN Reporter: You definitely get around...those frequent flyer rewards must be paying off! But what exactly is your success...I mean infection rate?

Mrs H: Although you humans have done a lot of probing of my kind, my infectious dose is actually unknown.  However, data compiled from all of our outbreaks puts us right up there with Shigella’s infectious dose – as few as 10 organisms. This would however depend on the person.


TFSN Reporter: Well then you are considered serious! What is the course of this serious infection?

Mrs H: As already said I cause acute hemorrhagic diarrhea, with abdominal cramping for about 5-10 days.  In children under 5 and the elderly, I can also result in acute haemolytic uremic syndrome (HUS). This syndrome destroys the red blood cells (hemolytic anemia) and kidney failure.  This is however quite rare and only occurs in 0-15% of all cases.  

TFSN Reporter: Oh my can you be killed...I mean the person treated?

Mrs H: I heard that! Most people recover with antibiotics in 5 – 10 days. However, HUS is life-threatening and I usually send the person to intensive care. I can normally be killed off after a few blood transfusion and kidney dialysis treatments, however, I can still cause death in about 3-5% of the cases.


TFSN Reporter: As food producers we are aware that prevention is better than cure. How are we as producers able to prevent you from contaminating our food?

Mrs H: Well...maybe you should not know this as it would impact on the existence of my species.  However, it is common sense that that if you eliminate the source, then you should eliminate the problem. By reducing the number of infected cattle, through the use of vaccines, and reducing the contamination of meat during slaughter and grinding, the infection rate is reduced.  Prevention measures assisting the latter include careful removal and cleaning of the intestine, steam/vacuum treatment and organic acid sprays.

TFSN Reporter: So at farm level we can already start obliterating you, but from our interview today, I can assume you survive the process. So what can we do at fork level?


Mrs H: Well, yes you are right, but thefollowing measures have caused many family deaths:
1. Cooking ground or minced meat thoroughly (must reach a core temperature of 72°C);
2. Preparation of meat should be kept separate from all other food items and all surfaces. All utensils that come are used for this prep should be washed thoroughly. Hands are also utensils so are similarly important;
3. Any unpasteurised milks, ciders, and juices are potential sources of E.coli;
4. Wash your fruits and veggies thoroughly. Alfalfa sprouts are our best vectors of transport, so eat at your own discretion;
5. Water should be boiled for at least one minute before consumption should you suspect contamination;
6. Proper hand-washing, after handling of infected patients, will reduce the risk of transmission.

TFSN Reporter: Thank you so much for being so honest with us during this interview Mrs. H. Your life facts will surely be used to prevent you from causing any more outbreaks as food manufacturers and food consumers will hopefully use what you have told us to prevent your incidence in their food.

Mrs H: No, thank you! Remember I am a living organism that also need to survive in the world and my aim in not to harm people or any other living creature.

TFSN Reporter: Well that is the end of our E.coli O157:H7 autobacteriography and part two of our Meeting with microbes Series.

Brace yourself..... you are becoming macroscopic..... Honey, I shrunk the readers ends!

Remember small steps and you will...
Let’s rephrase are MAKING SENSE OUT OF MICRO....



Created by 1021 Media and design | Copyright © The Food Safety Network 2009, All Rights Reserved. | Enabled by