Above: Image © arinarici,iStockPhoto.com

When you think about viruses and bacteria, maybe you think about being sick in bed. But did you know that there are certain viruses that can infect and kill bacteria? These viruses are called bacteriophages (or phages). Back in 1915 and 1917, the scientists who discovered phages also discovered the possibility of phage therapy, the use of phages to kill disease-causing bacteria in people with infections. However, when scientists discovered antibiotics in 1928, phage therapy research slowed down. This happened because antibiotics were easier to use.

But does that mean antibiotics are more effective than phages? Well, it depends. Let’s look at this debate in more detail.

Did you know? In 1917, Franco-Canadian scientist Felix’d Herelle successfully treated a patient suffering from dysentery using a virus preparation. This was even before the era of antibiotics.

Above: Image © ttsz, iStockPhoto.com

How do bacteriophages work?

Bacteriophages are microscopic particles with head and tail structures. The head contains viral nucleic acid. Some phages have tail fibres. Bacteriophages attach to bacteria using their tail or tail fibres. Then, they inject their nucleic acid into the bacterial cell. There, the virus multiplies. Finally, the newly produced virus will get released to the environment by bursting (killing) the bacterial cell.

Did you know? In 1896, scientists first noticed that water in the Ganges and Jumma rivers in India could kill the bacteria that causes cholera, but no one knew how. Later, researchers began to suspect that the rivers contained bacteriophages.

The superbug probem

Some bacteria, called superbugs, are resistant to antibiotics. Patients infected with superbugs are hard to treat with antibiotics. On the other hand, for any bacterial species, you can find a phage in nature that can kill it.

When bacteria become resistant to antibiotics, pharmaceutical companies have to invest in finding other ways to kill that bacteria. That costs money! Finding a phage to kill a bacterial species is cheaper and easier.

One interesting thing about microorganisms is that they change or evolve very fast. That means that bacteria are capable of changing to protect themselves from antibiotics as well as phage attacks. However, viruses also can change and produce more varieties of phages that can even kill superbugs! That’s another advantage of phage therapy.

Why won’t my doctor give me a phage?

Think of all the times you’ve gone to a doctor for an infected wound, or even for pneumonia. You’ve probably received an antibiotic, not a phage. So why aren’t phages used to treat bacterial infections as commonly as antibiotics are?

There are a few reasons. One major reason is the narrow host range (number of bacterial species a phage can kill). Usually, one specific bacteriophage only infects and kills one specific species of bacteria. For example, a phage that can infect and kill Streptococcus pneumoniae (a bacterium causing pneumonia) cannot infect and kill Campylobacter jejuni (a bacterium causing stomach flu).

    Phage Fast Facts

  • Phages won’t harm any of your cells other than the bacterial cells that they’re meant to kill.
  • Phage therapy has less side effects than antibiotics. However, some patients can have minor allergic reactions.
  • Human immune systems can sometimes recognizes phages as “foreigners” in your body and try to kill it. To prevent this, your doctor can give you a large amount of phage particles.

Meanwhile, there are antibiotics that can kill a wide range of bacterial species at the same time.

Let’s take the example of bacterial pneumonia. It can be caused by several bacteria. Two of them are Streptococcus pneumoniae and Haemophilus influenzae. Generally, both infections can be treated with an antibiotic called amoxicillin. So if your doctor recognized that you had the symptoms of pneumonia, but wasn't sure which species was causing it, they could give you amoxicillin and you would probably start to feel better. However, if your doctor wanted to use phage therapy, they would first need to order a laboratory test to identify which bacteria had caused your pneumonia. That’s because a phage capable of killing Streptococcus might not necessarily kill Haemophilus.

So, when the doctor is not sure about which bacteria caused the disease, prescribing antibiotics with a wide host range takes less time than running lab tests and then prescribing a phage. But when it comes to infections with superbugs, known antibiotics are ineffective and phage therapy is the best option to look for.

Is anyone using phage therapy?

Although phage therapy has not yet knocked out antibiotic treatments, there are many reports of doctors successfully treating superbug-infected patients with phages. One of the pioneering institutes in using phage therapy is the Eliava Institute in Georgia. There, phage therapy has successfully treated patients with skin ulcers, infected burn wounds, stomach bugs, eye infections, respiratory infections and more.

Other countries are also doing research on phage therapy to use it as an alternative to antibiotic therapy, especially to treat the superbugs. So when you go to the doctor with an infection in the future, instead of giving you a bottle of antibiotics, you just might get a vial containing a phage!

Learn more!

Bacteriophage (2008)
D. Goodsell, PDB-101

Did someone call the Superbug Exterminator? (2015)
CurioCity

Viral replication: lytic or lysogenic (2017)
Khan Academy

Damitha Gunathilake

I am a PhD student in molecular microbiology at the University of Calgary. Before coming to Canada, I earned bachelor’s and master’s degrees in Sri Lanka, where I also had opportunities to work in different research labs. My earlier studies and research focused on industrial microbiology, epidemiology of viral encephalitis and genetic diagnostics. I have also published several articles and papers on related topics. As I pursue a career as a microbiologist, I am excited about sharing my knowledge and experience with others through projects like CurioCity.