Page last updated at 07:32 GMT, Monday, 8 September 2003 08:32 UK

Gene find could halt bug peril

E.coli is a continuing health threat

Scientists have discovered dozens of E.coli genes which could eventually help them cut the number of human infections.

Some strains of E.coli - present in the guts of cattle - can cause dangerous food poisoning in humans.

Researchers at the UK Institute of Animal Health have found 60 E.coli genes which they think may stop the animals getting rid of the bug.

They hope that the finding could help cut the number of contaminated cattle.

Their findings, to be presented at the Society for General Microbiology Conference in Manchester on Monday, centre on the 0157 strain of E.coli.

Worst-ever outbreak

This is particularly dangerous version, implicated in the world's worst ever E.coli poisoning outbreak in Scotland which led to the deaths of 21 people who ate contaminated meat from a butcher's shop.

The very young and the elderly are most at risk when they eat contaminated food - although E.coli 0157 poisoning can produce severe illness in anyone who contracts it.

The fact that it can persist in the guts of infected animals means it is an ever-present threat in the food chain.

Dr Mark Stevens, from the Institute of Animal Health, in Compton, Berkshire, is one of those looking for a way to produce E.coli-free herds, and thus lessen the risk to the public.

He has looked closely at the genetic structure of the bacterium, and picked out 60 genes which appear to play a significant role in its ability to defeat all attempts by the animal's immune system to eradicate it.

Among these could be potential targets for treatments or vaccines that could prevent E.coli 0157 from colonising the cattle.

Overseas menace

Dr Stevens said that the work focused not only on the 0157 strain, but also on a lesser-known, but equally dangerous strain which is gaining a foothold on the Continent.

He said: "Although E.coli 0157 is particularly nasty, causing bloody diarrhoea and life-threatening kidney infections mainly linked to contaminated food or contact with farms, we are also worried about E.coli 026.

"This strain of bacteria is rare in the UK at the moment, but it is a rapidly growing threat to human and animal health in continental Europe.

"We have already identified more than 50 important genes from E.coli 026, which uses distinctly different mechanisms to colonise the intestines of cattle.

"We hope these studies will improve diagnosis, and give us a chance to develop vaccines and treatments in time to prevent it becoming a serious threat here."

'Good' bugs

Other research being presented at the conference on Monday is looking for ways to eradicate a bacterium which can become entrenched in the stomachs of humans, increasing the chances of serious disease.

H.pylori is thought to be behind the majority of stomach ulcers, and increase the risk of the carrier falling prey to gastric cancers.

Unlike most bacterial infections, it appears to be able to evade the immune defences that would normally be targeted to destroy such a bacterium.

Belinda O'Grady, a researcher at the School of Food Biosciences at the University of Reading, said that probiotic supplements - such as "active" yoghurts - might be able to tip the balance between "good" and "bad" bacteria in the gut, and keep H.pylori numbers down.

She said: "These good bacteria are like soldiers defending our gut wall, preventing attack and infection from the enemy."

E. coli infection
03 Aug 09 |  Health
E.coli breakthrough made
26 Feb 03 |  Scotland

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