An Ally Against Infectious Bacteria

For centuries, humans have fought in a lengthy battle against our mortal enemy: infectious bacteria. These microscopic microbes, too small to be seen through the naked eye, have wreaked havoc against organisms across all biological kingdoms, killing millions, maybe even billions over the course of history. Many attempts have been made to stop their destruction and some, like antibiotics, have significantly decreased it in the short run. However, these attempts are starting to show new, dangerous effects posing an even bigger issue. The issue in question? AMR.

For years, antibiotics have been used to stop the growth and survival of pathogenic microbes. In the case of bacteria, it has led to the development of antimicrobial resistance (AMR), or the resistance to many different antibiotics. This has had detrimental effects on humans all over the world. According to the World Health Organization, AMR has posed huge threats to public health globally, with an estimated 1.27 million deaths in 2019 directly correlated with it, and another 4.95 million deaths associated with its development (World Health Organization.) So, what’s the solution to infectious bacteria if not even antibiotics can help? Well, this is when one specific microorganism enters the battle. Its name is the bacteriophage.

Bacteriophages are essentially viruses of bacteria, and are key in the controlling of bacteria population, acting as an apex predator of the microbe. They specifically target certain bacteria strains, stopping host genome and protein replication, and use the host’s protein machinery to multiply the phage’s numbers. There are two main cycles bacteriophages use. The first is the lytic cycle. It begins with the phage attaching itself onto a host cell’s extracellular receptor, and injects its DNA into the host. Next is the shutdown of the host cell’s major macromolecule synthesis– like DNA replication– and instead, the production of the phage’s contents and enzymes to aid in this production occurs. Afterwards, maturation, or the assembling of the phage components occurs, and bacteriophage-coded enzymes cause osmotic lytic: the bursting of the cell releasing the newly synthesized phages. The other cycle, known as the lysogenic cycle, follows similar infection steps as the lytic cycle– except it does not kill the host cell. Instead, the cycle involves the fusing of viral DNA to the host’s, which gets passed down to future generations through mitosis.

So, how can phages benefit antimicrobial treatments against the effects of the dangerous bacteria? Well, throughout the years, scientists have discovered that bacteriophages can indeed be effective against certain bacteria strains (as a biocontrol agent), and according to an article published on National Library of Medicine, “phages have multiple advantages, including ubiquity, specificity, broad antimicrobial effects on several different serotypes strains and less interference to the normal flora” (Li et al.)

Even so, there is a continued limitation that solely relying on phage therapy to overcome a microbial infection is indeed not possible, as these phages are limited to very, very specific strains that they target. Currently, scientists all over the world are working together to solve these limitations, and have proposed some new ideas to counteract them. For example, one solution to this problem that has been proposed is the creation of a “phage cocktail”, a mixture of multiple phages in order to counteract the specificity characteristic of phages. Another proposed solution was the generating of recombinant phages– taking certain genes of other phage types and inserting them into one single phage to broaden host range to genetically different bacteria (Li et al.) Additionally, another limitation to consider is that despite being successful in multiple experiments, the long term effects of solely using bacteriophages have not been evaluated, making clinical usage not a current possibility. 

But who knows? Perhaps sometime in the near future, we will stand our ground against our deathly foe: the bacteria. With the help of advanced technology and our new knowledge of bacteriophages’ true powers, our newfound alliance might be the key to ending the era of succumbing to pesky bacteria, and instead open a door to tackling even greater issues, like climate change. Exciting, isn’t it?

---

Michelle Choi is a sophomore from Minnesota who actively participates in various STEM-related programs. Driven by her fascination of microbiology, she oftentimes finds herself watching YouTube videos or researching about the multitude of microbes in existence, while crocheting on the side.

References

Clokie, Martha RJ, et al. “Phages in nature.” NCBI, 2011, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109452/.

Johns Hopkins Medicine. “Escherichia coli O157:H7.” Johns Hopkins Medicine, https://www.hopkinsmedicine.org/health/conditions-and-diseases/escherichia-coli-o157-h7. Accessed 15 January 2024.

Li, Min, et al. “Recombination of T4-like Phages and Its Activity against Pathogenic Escherichia coli in Planktonic and Biofilm Forms.” NCBI, 25 May 2020, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7736419/.

Lin, Jiaxi, et al. “Limitations of Phage Therapy and Corresponding Optimization Strategies: A Review.” NCBI, 13 March 2022, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8951143/.

Mayo Clinic. “E. coli - Symptoms and causes.” Mayo Clinic, 1 October 2022, https://www.mayoclinic.org/diseases-conditions/e-coli/symptoms-causes/syc-20372058.

Oluwarinde, Bukola O., et al. “Order Article Reprints Open AccessReview Safety Properties of Escherichia coli O157:H7 Specific Bacteriophages: Recent Advances for Food Safety.” MDPI, 31 October 2023, https://www.mdpi.com/2304-8158/12/21/3989.

World Health Organization. “Antimicrobial resistance.” World Health Organization (WHO), 21 November 2023, https://www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance.