Phage 'cocktail' wipes out 99 percent of E. coli in meat, spinach

April 2, 2014 by Natalie Van Hoose, Purdue University

( —Treating food products with select bacteriophages - viruses that target and kill bacteria - could significantly reduce concentrations of E. coli, a Purdue University study shows.

An injection of bacteriophages - also known informally as "phages" - nearly eradicated a toxin-producing strain of E. coli in contaminated spinach and ground beef, in some cases decreasing E. coli concentrations by about 99 percent.

The study suggests that bacteriophage treatment could be an effective tool to help ensure the safety of food products, said Paul Ebner, associate professor of animal sciences.

"Phage treatment is a way of harnessing the natural antibacterial properties of phages to limit E. coli and other important foodborne pathogens," Ebner said. "Applying this kind of therapy to contaminated foods will make them safer."

While most strains of E. coli are harmless, some can cause severe and potentially fatal illnesses. The strain used in Ebner's study - E. coli O157:H7 - caused more than 63,000 illnesses, 2,100 hospitalizations and 20 deaths in the U.S. in 2011. Ingesting as few as 10 colony-forming units of E. coli O157:H7 can result in serious illness.

Most E. coli infections are caused by eating undercooked meat contaminated with the bacteria, but outbreaks associated with fresh produce such as spinach are on the rise.

Ebner and Purdue graduate students Yingying Hong and Yanying Pan infected fresh spinach leaves and ground beef with about 10 million cells of E. coli, a far greater amount than typically found in contaminated , Ebner said. The researchers then treated the food with a "phage cocktail," a liquid containing three kinds of phages selected for their ability to quickly and efficiently kill E. coli. Using a variety of phages also helps prevent the bacteria from developing resistance.

After 24 hours, the treatment had reduced E. coli concentrations in the spinach, stored at , by more than 99.9 percent. E. coli dropped by more than 99.8 percent and about 99.8 percent in spinach after 48 and 72 hours, respectively.

In ground beef stored at room temperature, the phages cleaned up about 99 percent of E. coli bacteria within 24 hours. The number of E. coli in refrigerated and undercooked shrunk by about 68 percent and 73 percent, respectively.

"Bacteria have viruses just like we do," Ebner said. "We're taking what already exists in nature and concentrating it to have an impact on these bacteria."

The search-and-destroy methods of phages sound like the stuff of science fiction: Spaceship-like phages dock onto the receptor sites of a host bacterium cell and deploy a syringe-like device that penetrates the cell wall. They inject their own DNA into the host cell, transforming it into a phage-making factory. The cell assembles phages until it contains so many it explodes, releasing the next generation of phages to find new hosts.

"Phages are the most abundant life forms on the planet - if you consider viruses to be alive," Ebner said. "You can eat thousands of phages just by licking your lips."

Ingesting phages does not pose a threat to human health because phages are highly host-specific, only targeting certain types of bacteria, said Ebner.

"Phage therapy is a way of using microbes beneficially, similar to using probiotics in yoghurt," he said.

Interest in using phages as antibacterial treatments has increased with the rise of antibiotic-resistant bacteria. The host specificity of phages can be an advantage over broad-spectrum antibiotics, which can wipe out both pathogenic and beneficial , Ebner said.

He said phage therapy is not a substitute for antibiotics, but "it can be very effective when used at specific time points and for shorter periods."

Explore further: Phagevet-P: Applying viruses to treat bacterial diseases

More information: "Development of bacteriophage treatments to reduce E. coli O157:H7 contamination of beef products and produce."
Y. Hong, Y. Pan, and P. D. Ebner. J ANIM SCI jas.2013-7272; published ahead of print. February 3, 2014. DOI: 10.2527/jas.2013-7272

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not rated yet Apr 02, 2014
It is a Russian neglected simple technic of 1920 years, very useful to prevent amputation of limbs due to of antibiotic-resistant bacterias !!!
Some travel to Georgia and keep their limbs !!!
They search theses phages in the very dirty water of rivers !!!
It is incredible that antibiotics have supressed completely this huge domain of natural bacteria lifes and biotop.
not rated yet Apr 02, 2014
"You can eat thousands of phages just by licking your lips" and cure your illness without knowing it !!!
not rated yet Apr 02, 2014
How about encouraging a hygenic supply chain ? Phages may kill off gross infestations, but what about the bacterial toxins ?
not rated yet Apr 03, 2014
Three years ago the FDA/USDA approved a phage-based cocktail effective against E. coli O157:H7. That product is called EcoShield (tm), developed and sold by Intralytix, Inc., a Baltimore-based biotech company. The company also has FDA/USDA approved phage cocktails effetive against Listeria m., and Salmonella spp. See: http://www.youtub...o1OVa11E for a video on using phages for food safety. These products are all natural, kosher, halal, and two are Organic Materials Research Institute (OMRI) listed.
Apr 03, 2014
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not rated yet Apr 03, 2014
The toxin risks parallel those that gave irradiation sterilisation of foodstuffs a bad name.
(IIRC, that 'supply chain' had to 'raise its game', so that irradiation was a precaution rather than a 'fix'...)

Yes, there's a place for phages but, like antibiotics, resistant strains of bugs will soon flourish...

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