Applications of bacteriophages for the control of veterinary pathogens, p. 41-68. In Boulanger A, Blanc M (ed.), Bacterial Pathogens: Virulence Mechanisms, Diagnosis and Management

The emergence of multi-drug resistant bacteria and the increased pressure from medical and public sectors to limit antibiotic usage in agriculture and the production of wholesome foodstuffs have prompted the need to search for alternative methods to control veterinary pathogens. Bacteriophages, viruses that infect bacteria, may play a critical role. The idea of using bacteriophages as therapeutic agents against bacterial infections, or ‘phage therapy’, is not new and has been around for almost a century. Despite its early breakthrough, phage therapy did not evolve towards routine use likely due to the discovery and ensuing popularity of antibiotics during the early 20th century. However, in the past two decades the emergence of antibiotic-resistant bacteria has generated an increased awareness as well as the need to search for “resistance-free” antimicrobials to protect consumer health. Therefore, phage therapy has again become a subject of major interest in treating bacterial infections. Although phage therapy has been historically associated with human medicine, bacteriophages have also been applied in veterinary medicine. Bacteriophages have been reported to be a safe and effective preventive/treatment modality against numerous bacterial infections of animals including Staphylococcus aureus infections in cows, Salmonella infections in poultry and swine, and Escherichia coli infections in poultry, calves, piglets, and lambs. Phage therapy has also been used to decrease or prevent the shedding of E. coli O157:H7 in cattle and for the decontamination of food intended for human consumption to prevent spread of zoonotic pathogens such as Listeria, Campylobacter and Salmonella. More recently, bacteriophage generated endolysin enzymes that target the integrity of the host bacterial cell wall have also displayed an efficient capacity to eradicate pathogens. With Earth-bound bacteriophage populations estimated to approach numbers as high as 1031, there is an enormous selection of bacteriophages available for targeted destruction of pathogens that is only beginning to be applied in the veterinary realm. This chapter will review the current state and future trends of phage therapy in veterinary medicine.