EFSA evaluates bacteriophages
In a recent opinion, EFSA’s BIOHAZ Panel concluded that under specific conditions, bacteriophages may be very effective in the elimination of specific pathogens from foods. However, based on data currently available in peer-reviewed scientific literature, the Panel could not conclude whether bacteriophages can protect against bacteria in case the food becomes re-contaminated. The efficacy of bacteriophages against re-contamination of food may vary according to the characteristics of the food itself, the type of bacteriophage and how it is used, and environmental factors.
The European Food Safety Authority (EFSA) was asked by the European Commission to provide advice on the use of bacteriophages on food of animal origin. In particular, it was asked to describe the mode of action of bacteriophages on food of animal origin (be it carcasses, meat and dairy products), and also if these have a continuous action in the final food.
EFSA’s BIOHAZ Panel (Biological Hazards) concluded that some bacteriophages, under specific conditions, have been demonstrated to be very effective in the targeted elimination of specific pathogens from meat, milk and products thereof. The Panel, however, could not conclude whether bacteriophages can protect against bacteria in case the food becomes re-contaminated.
The BIOHAZ Panel noted that bacteriophages infect specific hosts, and that these are generally limited to some bacterial species or strains. Bacteriophages occur in nature, have a broad range of habitats and may be isolated in considerable numbers from meat, milk and derived products. While bacteriophages replicate best on growing bacterial cells, they have also been shown to reproduce on those cells which are not in a growing phase.
The Panel also noted that some mutants which become insensitive to bacteriophages might exist in the populations of target bacteria. The frequency of these mutations and their consequences are likely to vary according to the specific bacteriophage, the mode of application and the bacteria concerned.
Regarding the length of their effect in the final product, the BIOHAZ Panel noted that bacteriophages behave as inert particles in the environment and tend to persist longer than their hosts. However, their long-term antibacterial activity is compromised on dry surfaces. Also, the persistence in food varies with each bacteriophage, and with the conditions of application, including dose, and physical and chemical factors associated with the food (e.g. pH, moisture levels etc..). For instance, refrigeration temperatures enhance persistence of bacteriophages on the surface of meat and on/in dairy products.
EFSA’s BIOHAZ Panel finally recommended that in order to further assess the persistence of bacteriophages in foods and their ability to prevent recontamination with bacterial pathogens, research for specific combinations of bacteriophages, pathogens and foods should be encouraged.