Food safety – Bacteriophage update by Dr. Ron Wasik

A bacteriophage (phage) is a virus that replicates within bacteria. What prompted me to re-explore the phages was a couple of chance email exchanges with two food science students at different Canadian universities doing research on these organisms. A number of advances in the application of phages have occurred and I felt that readers would appreciate reading not only my thoughts and opinions on the subject but also those of Thomas Brenner (UBC) and Lucas Risi (Ryerson).

Although it has been known for some time that phages can target a wide variety of bacterial pathogens of food safety concern, research on them was largely abandoned because it was more complex to understand than antibiotics and chemical sanitizers, which were seemingly-perfect solutions. However, the indiscriminate applications of antibiotics and sanitizers along the food chain has shown that antibiotics and sanitizers can have significant downsides.

Phages have a lot to offer. They are safe to consume, can be certified as both Kosher and Halal, can be classified organic, provide a clean label, can be formulated with or without preservatives and are cost-competitive. They are also effective under typical food storage conditions, can be genetically engineered to handle specific pathogens and do not alter the flavour, aroma, or nutritional value of food.

Phages can target food pathogens like Listeria monocytogenes, Salmonella enterica, Escherichia coli, Campylobacter and Shigella. Health Canada has only approved phage products to control the first two, with one for E. coli control awaiting approval.

Available phage products

SalmoFresh™ may be used on a variety of food products like fish, shellfish, fresh and processed fruits and vegetables, ready-to-eat poultry products prior to slicing and on raw poultry before or after grinding.

ListShield™ has been approved for use on ready-to-eat meat and poultry, smoked salmon, fresh-cut apples and long leaf lettuce.

PhageGuard Listex™ has been approved to treat ready-to-eat meats, smoked and fresh salmon, shrimp, cheeses and frozen vegetables.

PhageGuard S™ is approved for use on fresh poultry products and ground meat.

Means of application

Phages can be applied in variety of forms including a fine powder, as a liquid (drink, dunk or spray) and even within a protective emulsion for either internal or external use.

Typical results

Recently-published studies and product monographs have shown that phage treatments targeting Listeria S. monocytogenes and S. enterica in a variety of products can reduce counts by 1-2 logs or by 10-100 times. Phage treatments are typically applied as an adjunct to an existing food safety program to enhance pathogen control.

Shortcomings

Since phages are made up of proteins, they can be deactivated by certain environmental conditions including UV light, sanitizers, acidity, heat and chemical cleaners. As with antibiotics, bacteria can also develop resistance to phage treatments if given the time to do so. Unlike broad-spectrum antibiotics and sanitizers, which are effective across a wide variety of pathogens, phages are only effective against their targeted pathogen. To address this latter concern, phage “cocktails” containing as many as six different phages are available.

Research

Brenner is studying the versatility of environmentally-isolated phages for application across the poultry production continuum in free and encapsulated forms. He has demonstrated broad protection against the most widespread Salmonella strains when sprayed directly onto chicken breast that had been spiked with a mixture of foodborne Salmonella isolates. His research has also shown that encapsulated phages can be successfully delivered in sufficient concentrations to the lower digestive system of poultry where Salmonella is regularly harboured. Brenner intends to strategically leverage phage strengths to provide solutions tailored for the Canadian food industry. Reach him at: tbrenner@mail.ubc.ca.

Rici is investigating novel food safety controls and methods and this led him to explore phages. He is currently conducting a food industry survey on effectiveness and implementation of bacteriophages. The results of his survey will help shed light on food industry concerns about phages and to explore possible remedies. Reach him at: lucas.risi@ryerson.ca. 

Dr. R.J. (Ron) Wasik, PhD, MBA, CFS, is president of RJW Consulting Canada Ltd. Contact him at rwasik@rjwconsultingcanada.com