The Use of Bacteriophages in the Poultry Industry

Abstract

The emergence of multidrug-resistant infections and antibiotic failures have raised concerns over human and veterinary medicine worldwide. Poultry production has had to confront the problems of an alarming increase in bacterial resistance, including zoonotic pathogens. According to the European Food Safety Authority (EFSA), campylobacteriosis and salmonellosis have been the most frequently reported human foodborne diseases linked to poultry. This situation has strongly stimulated a renewal of scientists' interest in bacteriophages (phages) since the beginning of the 21st century. Bacteriophages are the viruses of bacteria. They are abundant in nature, and accompany bacteria in each environment they colonize, including human microbiota. In this review, we focused on the use of bacteriophages as therapeutic agents to treat infections and reduce counts of pathogenic bacteria in poultry, as biocontrol agents to eliminate foodborne pathogens on/in food, and also as disinfectants to reduce contamination on food-contact surfaces or poultry carcasses in industrial conditions. Most of the phage-based products are targeted against the main foodborne pathogens, such as Campylobacter jejuni, Salmonella spp., Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, and Clostridium perfringens. Phages are currently addressed at all stages of the poultry production "from farm to fork", however, their implementation into live birds and food products still provokes discussions especially in the context of the current legal framework, limitations, as well as public health and safety.

Keywords: bacteriophages; disinfection; food safety; foodborne diseases; multidrug-resistant bacteria; phage therapy; poultry.

Figure 1

Life cycle of bacteriophage. (1) Lytic cycle. (A) Attachment: the phage binds to a receptor on the bacterial cell surface. (B) Penetration: the phage inserts its DNA into the bacterial cytoplasm. (C) DNA replication and protein synthesis: the phage takes over the bacterial cell functions and directs the synthesis to produce of phage DNA copies and proteins. Bacterial DNA is degraded. (D) Assembly packaging: new phage particles are assembled within host cell. (E) Lysis: the phage produces an enzyme which destroys the bacterial cell wall, causing lysis and the release new phages. The bacterial host cell is destroyed. Progeny phages can infect further bacterial cells and the cycle starts again. (2) Lysogenic cycle. (A) Attachment: the phage binds to a receptor on the bacterial cell surface. (B) Penetration: the entry of phage nucleic acid. (C) Integration of phage DNA: the phage DNA then moves through the cytoplasm to the host bacterial DNA and integrates itself into the host genome. (D) Prophage stage: the phage DNA is incorporated into the bacterial genome and becomes a (noninfective) prophage. (E) The prophage is replicated along with the bacterial genome. The bacterial cell divides and prophage DNA is transferred into daughter cells. (F) Sometimes the prophage can be induced to become active. The prophage DNA is excised from the bacterial genome and enters the lytic cycle.

Figure 2

Examples of phage application in the poultry industry.