That's the Why

Why was the E.coli outbreak this year so dangerous?

Early this year, an outbreak of E.coli O104:H4 hit northern Germany hard, and cases also showed up in several other sites across Europe and in North America, sometimes causing severe symptoms such as bloody diarrhoea and a complication called haemolytic uraemic syndrome (HUS). Overall about 50 people died.

Why is this particular outbreak so dangerous? Teams around the world have been analysing the genetics of the bug to try to understand it better, and this month a release from the Society for General Microbiologydetails some of the insights.

“We have found that the E.coli strain responsible for the outbreak carries a very high number of genes known to be involved in disease,” says researcher Dr Lisa Crossman from The Genome Analysis Centre (TGAC) in Norwich.

“These include genes that influence the bacterium’s ability to attach to surfaces and survival genes that increase tolerance to high acidity, low oxygen, UV light and antibiotics.”

The E.coli strain associated with the outbreak also has the ability to produce Shiga toxins, which are linked with serious complications in infections.

Genetic sequences from different variants of the strain are now available, and this should offer a resource for finding out more about tackling it, according to the release.

“Knowing which antibiotic resistance genes are carried by the strain, for example, can provide us with more insight into the source of the outbreak and help us avoid similar outbreaks occurring in the future,” says Dr Crossman.

“By studying the genetic factors involved in the survival of this bacterium on surfaces, we hope to get an angle on how this organism has been able to get a foothold in the global food chain.”

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