Field of Science

My take on the new variant of the rare E. coli O104 strain

Germany, cucumbers and death are 3 words you wouldn’t particularly associate with one another (particularly the cucumbers and death part).  However, in the news this week regarding the E. coli outbreak in Germany, these 3 seemingly unconnected words have been dominating headlines.
Over 1,500 cases and 18 deaths have been caused by the food poisoning bug so far (
Cucumbers (via

Researchers and public health experts believe that the organism responsible for the E. coli outbreak in Germany is a ‘new form’.
I personally find this kind of exciting! So what does this mean? Basically there are hundreds of different types of E. coli – we call these strains, and group them by their different ‘H’ and ‘O’ proteins (E.g. O157:H7, O104:H4).
This ‘new form’ is thought to be a ‘variant’ from the rare O104:H4 strain. What this means is that this bacterium has the ‘O104’ and ‘H4’ proteins but has different ‘genes’ that have not been seen before in this strain.
These genes include:
1)    It produces a nasty toxin
2)    It can colonise the gut more efficiently
So not only is this variant ‘never been seen before in an outbreak’ (WHO) it is also believed to be ‘highly infectious and toxic’ (Beijing Genomic institute, China). The new variant of the rare O104 strain also looks like it’s acquired an ability to infect large numbers of people.

Not only is it a ‘new form’ it can also cause the deadly complication of ‘haemolytic-uraemic-syndorme’ (HUS) which is a rare complication, usually caused by E. coli O157:H7 strain in young children and the elderly.
HUS is caused by a toxin produced by the bacteria, which binds to and damages the kidney cells (as well as intestinal cells).  This is due to the toxin binding to a specific glycolipid that is found in high concentrations on intestinal and kidney cells. This toxin destroys kidney cells and affects kidney function, resulting in acute renal failure.
The disease also causes a decrease in platelets and microangiopathic haemolytic anaemia (which is destruction of red blood cells due to trauma). Death usually occurs in 3-5% of those who develop HUS.
However, the current outbreak has seen HUS predominantly in young adult females (now I’m worried), which is highly unusual and could be due to the type of food that was originally infected - Dr Dilys Morgan, from the Health Protection Agency (via

The outbreak was thought to have been from infected Spanish cucumbers (hence the cucumbers) however this was later deemed not the source of the outbreak. The source is still unclear however the organism’s gene which enables it to colonise the gut is also likely to enable the organism to attach to salad leaves - Professor Gad Frankel, Imperial College London (via

A new variant of a rare strain is not unexpected. Bacteria are continually evolving and developing resistance to current antibiotics (e.g. MRSA). In order for them to survive they evolve new ways of causing disease, like the current E. coli O104 variant.
Scientists know this and are continually planning and developing new ways to treat and control outbreaks when they occur.

In the mean time: If you don’t want to catch E. coli O104:H4 make sure you wash your fruit and vegetables and wash your hands before eating, as well as after using the toilet. Regularly disinfecting food surfaces is also a good idea.
The most IMPORTANT thing in preventing infection is good hand hygiene and effective disinfection!

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