Bowel cancer is the second biggest cancer killer in the UK
A virulent strain of E.coli could be linked to the second-biggest cancer killer in the UK, a new study reveals.
Scientists at Edinburgh University have found a "strong" suggestion the bacteria is able to hamper the body's fight against bowel cancer.
They now hope the findings from their pilot study will lead to more research into the causes of the disease.
The team studied colon cells infected with a strain of the bacteria known as enteropathogenic E.coli (EPEC).
They found the bacteria significantly reduced the levels of two key proteins needed to repair damage to DNA.
The EPEC bacteria achieved this by attaching to the colon cells and inserting proteins into them which appeared to inactivate the cells' repair system.
It is known that a breakdown of this system puts the colon cells at greater risk of becoming cancerous.
The scientists also looked at tissue samples taken from colon cancer patients.
From that research they found that 50% of the tumour samples were infected with E.coli, and half of those tested positive for virulent strains such as EPEC.
Lead author of the study, Dr Oliver Maddocks, of the university's school of molecular and clinical medicine, said the research uncovered a "brand new suspect" in the hunt for possible causes of bowel cancer.
Dr Maddocks, on a scholarship with the University of Maryland in the US, said: "We can't say for certain that this type of E.coli bacteria definitely causes colon cancer, as it is possible these patients acquired the bug after their tumours developed.
"But our laboratory work does strongly suggest that the bacteria are able to influence colon cells in a way that might predispose them to cancer, and so there is a real chance that infection could aid the development of colon tumours.
"We hope our findings stimulate further research to clarify the causes of this common cancer."
He added: "You can treat an acute EPEC infection with antibiotics and that has been shown to be effective.
"What we don't know is whether that short-term treatment gives a long-term complete eradication of the bacteria."
Each year more than 35,000 people are diagnosed with bowel cancer in the UK and about 10,000 die of the disease.
EPEC infection, which can stem from poor food-hygiene practices, can cause diarrhoea, particularly in children.
However, it may be carried by children and adults without causing any symptoms.
Current estimates suggest that between two and 10% of the healthy population carry EPEC.
The research is published in the Public Library of Science One journal.