What is bacteriophage therapy used for?

Bacteriophage therapy is an option to cure infectious diseases when antibiotic resistance or serious side effects make it impossible to use antibiotics. At the same time, it is an experimental and complex therapy.

What is bacteriophage therapy used for?
The use of bacteriophage in the treatment of bacterial illnesses. Photo by Roberto Sorin / Unsplash

Antibiotic resistance is a common trend worldwide. When antibiotic therapy is needed, it may not work, so medics and scientists are looking for other methods to cure infectious diseases. One solution to antibiotic resistance is to start using bacteriophage therapy.

Simply put, bacteriophages are viruses that attack bacteria in the human body. There are two types: moderate or lysogenic bacteriophages, which bring a new property to bacteria, make them strong and can cause very serious diseases. And there are lytic viruses, which do the opposite—they destroy the bacteria. These are not viruses that could affect human or animal cells in any way, but only bacterial cells, and that is their uniqueness.

Lytic bacteriophages penetrate bacteria, use the bacterium as a place to breed, and then tear the bacterium in half and move on to the next one. So the result is that we get new bacteriophages, but the bacteria themselves die. These are what we consider to be good bacteriophages.

Moreover, scientists are certain that while temperate bacteriophages may become lytic or good, lytic bacteriophages will never become temperate. This gives them the security to use lytic bacteriophages in therapies to fight a variety of infections. Once the bacteria are destroyed, the bacteriophages die.

Bacteriophages have the advantage and disadvantage of being highly specific.

So any bacteriophage will not work for one particular bacterium; there will be a specific bacteriophage that we have to use. The other is that it will not always be able to kill that bacterium, and then there is this geographical difference: the bacteriophages that work in Europe may not work in the Americas.

Furthermore, producing bacteriophages for medical purposes is a highly complex and expensive process that relies on a bacteriophage collection in which the bacteriophages have been thoroughly described, studied, and all of their genetic material is known. Only when all of the information is available is it considered a potential therapeutic bacteriophage.

Next, we look at how it interacts with already-pathogenic bacteria that are real, disease-causing bacteria. Then we have to look at the stability of the bacteriophage; we will not be able to use a bacteriophage that will die in a day in the fridge.

Once all the criteria are met, the bacteriophage is taken out of the biobank, or bacteriophage library, and bacteriophage production is started in special laboratories according to a myriad of requirements. Because of its great complexity, it is still an experimental therapy today—a therapy to be used when nothing else works.

In cases where there is either overwhelming antimicrobial resistance or where giving antibiotics can lead to very severe, previously known side effects, no more antibiotics can be given. So the therapy is based on virtually any infection that we cannot cure with antibiotics.

At the same time, there are very strict rules on how we give these bacteriophages—it is a complex therapy. With poor control of the therapy, there is the possibility that there would be many cases where people would say that they did not work, but in reality, they did not work because they were being used incorrectly.