Phages and Food Safety

Bacteriophages (or phages) are viruses that only infect bacteria, and their use in medical practice is widely documented. Phage therapy to treat bacterial infections has been used in the ex-Soviet Union since the early 1900s. Interest in phage therapy was lost amongst the discovery of antibiotics, but the rise of resistance has caused a comeback in phage research. With an ever increasing population and food consumption, the ability to control food safety is becoming more and more difficult, and phage application offers a promising solution in the control of food-borne pathogenic organisms (see articles referenced below). Phages are already being used in the food industry for the control of Listeria monocytogenes, a food-borne pathogen that can cause severe infections in pregnant woman and their neonates as well as the immunocompromised and elderly. The ability to grow at low temperatures makes this pathogen particularly difficult to control. Since 2006, the FDA has licensed the use of several phage cocktails to inhibit L. monocytogenes growth in meat and cheese products. So what are the benefits of using phages over conventional antimicrobials in the food industry?

• Unlike antibiotics, they evolve to combat bacterial resistance: there is a constant arms race between phage and bacteria.
• Cost: phages are ubiquitous in nature and are cheap to produce, unlike antimicrobials.
• Generally regarded as safe (GRAS) status: they are non-toxic to eukaryotic cells and are regularly consumed in food and water.
• Very high specificity: they can be used to selectively inhibit the growth of pathogenic organisms in the gastrointestinal (GI) tract of animals, reducing the risk of food-poisoning outbreaks.

With all of these benefits and use already in the food industry, you may be wondering why phage application has not been more widely adopted. This is partly due to lack of research on the safety and efficacy of phage application, causing resilience of consumers to ingest these edible viruses. There are also concerns over emerging resistance; superbugs already resistant to our last line of antibiotics that are not susceptible to phages is a worrying concept. However, the use of phage cocktails minimizes this risk of resistance, and continuous monitoring of resistant populations will enable these preparations to be altered as soon as resistance arises. With further research and more companies exploring the use of phages, impetus for commercial use of phages in the food industry is set to increase. In time, consumers may be more likely to opt for the use of these edible phages instead of chemicals and conventional antibiotics. References

1. Phage and their lysins as biocontrol agents for food safety applications. Coffey B, Mills S, Coffey A, McAuliffe O, Ross RP. Annu Rev Food Sci Technol. 2010;1:449-68.
2. Bacteriophage for biocontrol of foodborne pathogens: calculations and considerations. Hagens S, Loessner MJ. Curr Pharm Biotechnol. 2010 Jan;11(1):58-68.
3. Bacteriophages as biocontrol agents of food pathogens. Mahony J, McAuliffe O, Ross RP, van Sinderen D. Curr Opin Biotechnol. 2011 Apr;22(2):157-63.

Do you work in this field? How confident do you feel about the contribution phages could make to food safety? Let us know.