The US Food and Drug Administration has approved bacteriophages - bacteria-killing viruses - for use as a food additive. The idea is that cold, cooked meats will be sprayed with a combination of viruses to get rid the Listeria monocytogenes bacterium.

The Listeria bacterium causes an infection called Listeriosis, which can be very serious for those with weakened immune systems, pregnant women, and newborn babies. In the US, it is thought to cause around 500 deaths every year.

The six viruses are actually grown in vats of the Listeria bacteria they are designed to destroy, and are then purified before use. Wired reports that the FDA had been concerned that the viruses would retain some toxins from the growth process.

However, testing found no residual toxins and the FDA has concluded that the phages are safe to use, provided regulations are followed. The administration added that trace amounts of the toxins are unlikely to cause health problems, according to reports.

The use of bacteriophages will be regulated by the Department of Agriculture, but consumers will not be made aware of the foods that have been treated.

Intralytix, the company responsible for the virus cocktail, initially applied for FDA approval back in 2002. It says it has already signed a licensing deal with one major food manufacturer, and says it plans to market the phages worldwide.

Next up, company president John Vazzana says, Intralytix plans to develop a phage to attack the E.coli bacterium on beef, before it is minced. ®