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An artist’s rendition of a bacteriophage

An artist’s rendition of a bacteriophage (nopparit, iStockphoto)

STEM in Context

Phages vs. Antibiotics

Damitha Gunathilake
Format
Readability
8.12
Subjects

Summary

Many doctors prescribe antibiotics to cure infections. But should they be prescribing viruses instead?

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. For short, they are often called phages

Bacteriophages were discovered by two different scientists working independently of each other. Frederick W. Twort discovered them in Great Britain in 1915, and Canadian Félix d’Hérelle discovered them in France in 1917. These scientists also discovered the possibility of phage therapy. This is the use of phages to treat bacterial infections. However, when scientists discovered antibiotics in 1928, phage therapy research slowed down. This happened because antibiotics were easier to use.

Fighting Infection with Phages (2018) by the National Institute of Allergy and Infectious Diseases (NIAID) (2:52)

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, Canadian scientist Félix d’Hérelle successfully treated dysentery with a virus preparation. This was before the era of antibiotics.

Labelled diagram of the parts of a bacteriophage
Labelled diagram of the parts of a bacteriophage (Source: via iStockPhoto ).

How do bacteriophages work? 

Bacteriophages are microscopic particles with a head and tail. The head contains viral nucleic acid. Some phages have tails and some have tail fibres.

Bacteriophages attach to bacteria using their tail or tail fibres (A). Then, they inject their nucleic acid into the bacterial cell (B). There, the virus multiplies (C, D). Finally, the newly-produced virus would burst (kill) the bacterial cell (E).This would release the virus into its host’s environment.

Viruses reproduce by attaching to a cell (A), injecting their DNA (B), multiplying their parts (C), assembling mature viruses (D), and releasing the new viruses into the environment (E)
Viruses reproduce by attaching to a cell (A), injecting their DNA (B), multiplying their parts (C), assembling mature viruses (D), and releasing the new viruses into the environment (E) (Source: Let’s Talk Science).

Did you know? 

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

The Superbug Problem 

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

What happens 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.

Microorganisms can change or evolve very quickly. That means bacteria are capable of evolving to protect themselves from antibiotics and phage attacks. However, viruses can also evolve. That means they can potentially produce more varieties of phages. They can potentially evolve to produce phages that can even kill superbugs! That’s another advantage of phage therapy.

Why won’t my doctor give me a phage?

Have you ever gone to a doctor for an infected wound? How about for a serious infection like pneumonia? Your doctor probably prescribed 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. A host range is the number of bacterial species a phage can kill. Usually, one specific bacteriophage only infects and kills one specific species of bacteria. For example, Streptococcus pneumoniae is a bacterium causing pneumonia. Campylobacter jejuni is a bacterium causing stomach flu. A phage that can infect and kill Streptococcus pneumoniae cannot infect and kill Campylobacter jejuni.

Phage Fast Facts

  • Phages won’t harm any of your cells except for the bacterial cells that they’re meant to kill.
  • Phage therapy has fewer side effects than antibiotics. 
  • On the other hand, most antibiotics have a much wider host range. Some antibiotics can kill a wide range of bacterial species at the same time.
  • The human immune system sometimes recognizes phages as “foreigners” and try to kill them. To prevent this, doctors can give their patients large amounts of phage particles.

 

Let’s take the example of bacterial pneumonia. It can be caused by several species of bacteria. Two of them are Streptococcus pneumoniae and Haemophilus influenzae. Generally, both infections can be treated with an antibiotic called amoxicillin. Let’s imagine that your doctor diagnosed you with pneumonia. However, they weren’t sure which species was causing it. They could give you amoxicillin, and you would probably start to feel better. 

However, let’s imagine that your doctor wanted to use phage therapy. First, they would have 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.

Streptococcus pneumoniae (left/gauche) and Haemophilus influenzae (right/droite)
Streptococcus pneumoniae (left) and Haemophilus influenzae (right) Sources (ktsimage via iStockphoto and ClaudioVentrella via iStockphoto).

 

So when a doctor is not sure about which bacteria is causing a disease, they will probably prescribe antibiotics. Antibiotics have a wide host range. Also, antibiotic treatment takes less time than running lab tests and then prescribing a phage. But when it comes to infections with superbugs, known antibiotics are ineffective. In these cases, phage therapy might be a better option. 

Is anyone using phage therapy?

Phage therapy has not yet eliminated the need for antibiotic treatments. But there are many reports of doctors successfully treating superbug-infected patients with phages. The Eliava Institute in Georgia is one of the first institutes to use phage therapy. There, phage therapy has successfully treated patients with skin ulcers, infected burn wounds, stomach bugs, eye infections, respiratory infections and more. These infections tend to be hard to treat. Doctors often use bacteriophages in combination with antibiotics. That’s because a wound can contain multiple pathogens. It is difficult to quickly select a bacteriophage for each one.

Did you know? 

Scientists are also researching ways to use phages to prevent and treat diseases in cattle. They are also researching using phages as disinfectants in dairy facilities.

So who knows? Maybe someday in the future, you’ll have a bacterial infection and visit your doctor. And instead of a bottle of antibiotics, you just might get a vial containing a phage! 

Starting Points

Connecting and Relating
  • Have you ever had a bacterial infection? What was done to treat the infection? 
  • How would you feel if the doctor determined that you had an antibiotic-resistant infection? 
  • What are your thoughts about being given a phage to treat an illness?
Connecting and Relating
  • Have you ever had a bacterial infection? What was done to treat the infection? 
  • How would you feel if the doctor determined that you had an antibiotic-resistant infection? 
  • What are your thoughts about being given a phage to treat an illness?
Relating Science and Technology to Society and the Environment
  • How are hospitals dealing with superbug problems? 
  • How are health authorities responding to superbug issues? 
  • What can individuals do to help reduce superbug problems?
  • Has society become too complacent about the availability of antibiotics to cure bacterial infections? Explain.
Relating Science and Technology to Society and the Environment
  • How are hospitals dealing with superbug problems? 
  • How are health authorities responding to superbug issues? 
  • What can individuals do to help reduce superbug problems?
  • Has society become too complacent about the availability of antibiotics to cure bacterial infections? Explain.
Exploring Concepts
  • Why are medical researchers seeking alternatives to antibiotics? 
  • How does a bacteriophage reproduce? What conditions does a bacteriophage need to reproduce? 
  • What is a superbug? Why have they become a serious problem?
  • What are the differences between antibiotic therapy and phage therapy?  
  • For which conditions has phage therapy been successfully applied?
Exploring Concepts
  • Why are medical researchers seeking alternatives to antibiotics? 
  • How does a bacteriophage reproduce? What conditions does a bacteriophage need to reproduce? 
  • What is a superbug? Why have they become a serious problem?
  • What are the differences between antibiotic therapy and phage therapy?  
  • For which conditions has phage therapy been successfully applied?
Nature of Science/Nature of Technology
  • If you were a scientist, would you prefer to look for a new antibiotic or a new bacteriophage? Explain your choice. 
  • Should medical researchers give up on looking for new antibiotics and focus solely on developing bacteriophage therapies? Why or why not?
Nature of Science/Nature of Technology
  • If you were a scientist, would you prefer to look for a new antibiotic or a new bacteriophage? Explain your choice. 
  • Should medical researchers give up on looking for new antibiotics and focus solely on developing bacteriophage therapies? Why or why not?
Media Literacy
  • What have you heard in your local news media about superbugs? What facts are generally reported?
Media Literacy
  • What have you heard in your local news media about superbugs? What facts are generally reported?
Teaching Suggestions
  • This article can be used for Biology and Human Health & the Body to support teaching and learning about bacteria, viruses and methods of treatment for bacterial and viral pathogens. Concepts introduced include viruses, bacteriophages, antibiotics, evolve, nucleic acid, superbugs, host, immune system and amoxicillin.
  • After reading the article, teachers could have students create a Venn diagram that compares and contrasts antibiotic therapy to phage therapy.
  • Teachers could have students consider the positive and negatives aspects of phage therapy by completing a Pros & Cons Organizer. Download ready-to-use Pros & Cons Organizer reproducibles in [Google doc] and [PDF] formats.
Teaching Suggestions
  • This article can be used for Biology and Human Health & the Body to support teaching and learning about bacteria, viruses and methods of treatment for bacterial and viral pathogens. Concepts introduced include viruses, bacteriophages, antibiotics, evolve, nucleic acid, superbugs, host, immune system and amoxicillin.
  • After reading the article, teachers could have students create a Venn diagram that compares and contrasts antibiotic therapy to phage therapy.
  • Teachers could have students consider the positive and negatives aspects of phage therapy by completing a Pros & Cons Organizer. Download ready-to-use Pros & Cons Organizer reproducibles in [Google doc] and [PDF] formats.

Learn more

Fighting Fire with Fire: Killing Bacteria with Virus (2018)

Harvard University's Science in the News gives an overview of the discovery and history of phage treatments, and the current research and difficulties in the field.

The Deadliest Being on Planet Earth – The Bacteriophage (2018)

This video (7:08 min.) by Kurzgesagt illustrates, with graphics, the structure, life cycle and uses of phages.

Bacteriopage Lytic Cycle (2012)

This video (0:58 min.) animation by JohnArt describes the steps of the bateriophage lytic cycle.

Bacteriophage vs ecoli animation (2014)

This video (2:40 min.) animation by Anson Call depicts modified bacteriophage vs E. coli bacteria.

What Are Bacteriophages & How Do Bacteriophage / Phage Viruses Work? (2016)

This video (4:31 min.) with animation by iC0NB0Y explains the enormous number of bacteriophages in existence, their lytic cycle and the possibilities for their use in medicine.

Eliava Institute

The website of the Eliava Institute in Georgia, a major research centre dedicated to phages.

References

Bailey, R. (2018, September 5). 7 facts about bacteriophages. ThoughtCo.

Clokie, M., Millard, A., Letarov, A., & Heaphy, S. (2011). Phages in nature. Bacteriophage, 1(1), 31-45. DOI: 10.4161/bact.1.1.14942

Gutiérrez, D., Fernández, L., Rodríguez, A., & García, P. (2019). Role of bacteriophages in the implementation of a sustainable dairy chain. Frontiers In Microbiology, 10. DOI: 10.3389/fmicb.2019.00012

Loc-Carrillo, C., & Abedon, S. (2011). Pros and cons of phage therapy. Bacteriophage, 1(2), 111-114. DOI: 10.4161/bact.1.2.14590

Molteni, M. (2019, May 8). Genetically tweaked viruses just saved a very sick teen. Wired.

Morozova, V., Vlassov, V., & Tikunova, N. (2018). Applications of bacteriophages in the treatment of localized infections in humans. Frontiers In Microbiology, 9. DOI: 10.3389/fmicb.2018.01696 

Stern, A., & Sorek, R. (2010). The phage-host arms race: Shaping the evolution of microbes. Bioessays, 33(1), 43-51. DOI: 10.1002/bies.201000071

Sulakvelidze, A., Alavidze, Z., & Morris, J. (2001). Bacteriophage therapy. Antimicrobial Agents And Chemotherapy, 45(3), 649-659. DOI: 10.1128/aac.45.3.649-659.2001