Killer vegetables!

What is E. coli and why is it so deadly?

The deadly outbreak of E. coli in Germany was thought to have originated from cucumbers or bean sprouts. So why is this bacteria so deadly? Well, we need some facts to start us off:

1. E. coli is normally found in our intestines and is harmless
2. It usually colonises (grows in) a baby's gut 40hours after birth!
3. Where ever E. coli is found, it is usually due to exposure to human poo!
4. As it is a bacteria, it can become immune to antibiotics!

This deadly strain of E. coli is very special. It's fancy name is 0104:H4 and it produces a toxin and a glue type substance found in other types of E. coli. This makes it very special as the glue is very rare and normally found in a different type of E. coli.

The toxin

The toxin is called the Shiga toxin and it is not very nice. It has an inhibitory effect on cells and stops cells making proteins. Now this is a big problem as proteins are the scaffolding that supports your cells. If you take that away, the cell collapses, becomes weak, dies and splits open. Now as E. coli is in your intestines, it affects the cells lining the gut, if the cell dies, this releases all the fluid inside the cell into the intestine. As the cells die, they are continually replaced and the process repeats itself over and over. This leads to the build up of fluid in the gut and thus diarrhoea.

It can get worse! If the rate of cell break down and death is greater than the rate of repair, we can start to rupture the many tiny blood vessels that surround the intestines and start to bleed into the gut and get bloody diarrhoea.

If this continues death usually results from severe dehydration and electrolyte imbalance. This means that you don't have the right amounts of sodium, potassium and other essential minerals in your body. They have all been lost from your cells as they split open. Death usually occurs in 4-5 days.

...worse still!

The toxin also targets the kidneys if it gets into your blood. It can attack the tiny tiny blood vessels that filter your blood called the glomerulus and cause something called Hemolytic-Uremic Syndrome. What happens is the toxin triggers a cascade of events in the glomerulus that activate part of your blood's clotting system (specifically von Willebrand Factor). This results in mini blood clots forming and travelling round the body blocking off blood supplies to vital organs which results in organ failure. The clots also block red blood cells, so they have to squeeze past and split in doing so - this is called Hemolysis (Hemo = Blood / Lysis = Split!) and it reduces your oxygen carrying capacity, which with the reduced blood flow is dangerous for your organs, especially your brain.

The glue

The glue makes the situation doubly treacherous. It means that bacteria have been stuck to the intestine wall more strongly than usually. They have been stuck on with super glue instead of prit-stick! As they are well attached they can just pump out the toxin that causes all the damage and the body's defences can do very little about it.

Hopefully there wont be any more deaths from this poisoning outbreak. I bet you will wash all your fruit and salad from now on.... i know i will!

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