A review of bacteriophage as a biocontrol agent against pathogens in farm animals responsible for foodborne diseases

Farm animals are important reservoirs for foodborne pathogens such as non-typhoidal Salmonella enterica, pathogenic Escherichia coli, Campylobacter jejuni, C. coli and Listeria monocytogenes. Intensive animal farming, due to global demand, has led to increased risk of contamination along the production chain up to the consumer's table. The main aim of this review is to evaluate the potential of bacteriophages as biocontrol agents against foodborne bacterial pathogens in farm animals, with particular emphasis on their effectiveness in controlling multidrug-resistant bacteria, applications across the farm-totable continuum, advantages, and challenges associated with their implementation in food animal production. Antibiotic-resistant strains have been found in these pathogens that make clinical treatment ineffective if foodborne illness is caused by a multidrug-resistant (MDR) strain. In order to overcome these MDR bacteria, bacteriophage or phage has recently shown promising antibacterial activity with flexibility to be utilised in various ways such as animal disease treatment, husbandry sanitation, processing equipment sanitation, and biopreservative in food. There are two types of phages, namely lytic phage and lysogenic phage, but only lytic phage is useful for biocontrol purposes. Lytic phage will bind to targeted bacterial cells before taking over host machinery to produce more viral particles before eventually lysing the cell to release new phage progeny. Phage has been reported to significantly reduce bacteria by 1 to 2 log CFU but not completely remove them. Despite the application of phage showing promising potential, it faces challenges such as efficacy consistency, especially when applied in the field and consumer limited acceptance of “viruses” added to their food product as preservatives. Addressing these concerns with formulation optimisation, protocol standardisation and educational implementation strategies is crucial to transform phage into a standard biocontrol practice in animal farming.