Phages: The viruses that offer a sustainable alternative to antibiotic treatment in livestock

Phages, which generate a lower risk of antibiotic resistance, can potentially treat bacterial infections in animals without compromising human health

By Brenda Coromina

An article by Manny I. Fox Morone in the Chemical and Engineering News Magazine investigates how non-profit organizations like the International Livestock Research Institute (ILRI) have been exploring the use of bacteriophages, naturally occurring and abundant viruses that target bacteria, as an alternative to antibiotics in the treatment of bacterial infections in livestock and food production. 

Phages to fight AMR, 

Infographic created by Annabel Slater

The overuse of antibiotics over the last several decades has caused many of the targeted bacteria to build up resistance to these antimicrobial drugs, making both humans and animals more vulnerable to bacterial infections. 

What makes phages such a promising alternative is that unlike antibiotics, which indiscriminately destroy good and bad bacteria, phages specifically target harmful bacteria by injecting themselves into the bacterial cells, reproducing until the bacteria are destroyed, and then dispersing. More importantly, because phages co-evolve with bacteria, there will always be a new phage to infect and destroy emerging phage-resistant bacteria—at least in theory. 

At ILRI, senior scientist Nicholas Svitek, who works to combat Salmonella in animals, has been contributing to phage research by exploring the prospects of phage encapsulation to increase the survival of phages in chicken. The purpose of his research is to test materials that can protect phages as they travel through the harsh environment of a chicken's gastrointestinal tract. 

Nevertheless, the widespread use of phages to treat microbial diseases, particularly in the Global South, is not without obstacles. For example, as of now, they must be stored at 4°C, which poses a storage problem for farmers without adequate resources. To mitigate this, scientists have been exploring methods of storage that do not require refrigeration, like spray-drying, which would allow phages to be stored at room temperature for extended periods of time—although further testing is still necessary to achieve this. 

Because phages self-amplify— the viruses reproduce only up to the necessary amount that would destroy targeted bacteria—farmers would not need to worry about the dangers of overuse in their livestock, unlike with antibiotics.

However, the solution is neither simple nor one-size-fits-all. Since it is ultimately farmers who would be treating their livestock with phages, it is crucial that the options consider farmers’ needs, available resources, and perspectives.

In an interview with Chemical and Engineering News Magazine, ILRI postdoctoral scientist Angela Makumi stressed the importance of understanding the dynamics of the farm system to inform the adoption of any new product development. By consulting farmers in the process, new phage technologies can disrupt the growing threat of antimicrobial resistance. 

Photo credit: Phages arrest the growth of bacterial culture (ILRI/Paul Karaimu)