Salmonella is traditionally associated with food poisoning, but scientists say a genetically-engineered form of the bug could be beneficial for humans.

Vion Pharmaceuticals has applied for a licence to test its treatment, known as the TAPET vector, on humans in both the US and Europe.

It says tests on monkeys and mice have shown the treatment is effective and safe.

Scientists from the company presented their findings to the American Association for Cancer Research on Sunday.

They claim the vectors can help improve the targeting of anti-cancer drugs at tumours.

Even without anti-cancer drugs attached to them, they can inhibit the growth of primary and spreading tumours by more than 90% and prolong the lives of mice which have been implanted with human cancer tissue, claims Vion.

Toxicity reduction

David Bermudes, associate director of biology at Vion, says genetically engineering salmonella means its toxic effects, such as septic shock, are reduced by as much as 10,000 times.

Vion claims cynomolgous monkeys given the genetically-engineered bacteria in high doses showed no toxic effects.

It says the treatment is also rapidly cleared from the bloodstream and is undetectable within 24 hours.

When it was injected intravenously into mice which had been transplanted with human melanoma, colon, lung, prostate and breast tumours, it effectively targeted tumours rather than other tissue.

It accumulated in tumour tissue up to 500 times more than in non-cancerous tissue.

Mice given the vector treatment lived longer than those not given it.