Understanding news reports about Science can be a daunting task. Usually, the reader gets lost one or two paragraphs into the article. What ends up happening is that the catchy title sticks and news spreads with little attention paid to the actual details of the research. Gayatri Muthukrishnan simplifies some facts on superbugs and how to fight them.

Sometimes reading an article beyond the headline and understanding beyond the first paragraph is an important first step to understanding science news.

For example, a lot of articles talk about discovery of a drug that might cure cancer. But if you read the details, most likely, the discovery would be that of a molecule that has shown some potential to cure one type of cancer in a laboratory setting under specific conditions in a mouse, which is not the reality of most cancer patients.

In this series of blogs, I will attempt at taking you through a journey of understanding Biology significant to our daily lives. I will also highlight current research being done in the field, from labs, either in India or Switzerland. I hope you will enjoy learning about the Science and appreciate the importance of scientific research in the process.

Antibiotic Resistance and Superbugs

To understand this, we would first define bacteria, which are single-celled, micron-sized organisms that are neither plants nor animals. They are at least 10 times smaller than human cells and can be found in every nook and corner of the world, including inside of us. While good bacteria like Lactobacillus live in the gut and help with digestion, there are many that make humans sick. Before the discovery of antibiotics, people could die of simple cuts or the common cold because of bacterial infection. Discovery of penicillin in the 1920s and a multitude of other antibiotics since has increased life expectancy of people many times over.

But now we have come to a stage where we need to fear bacterial infections yet again. This is because of ‘antibiotic resistance’, where bacteria can no longer be killed by any drug. These bacteria are termed ‘superbugs’.

The adage by Friedrich Nietzsche: “What does not kill me makes me stronger” (German: Was mich nicht umbringt macht mich stärker) is absolutely apt for bacteria.

Currently, with the onset of bacterial infection, if the last line of antibiotics fail, there is nothing more that a doctor can do to save the life of a patient. It is also worrying that these superbugs develop fast and can travel long distances through tourists. For example, in Switzerland there are reports of strains of antibiotic-resistant enterococci and E. coli that have traveled all the way from the Australian continent and India, respectively. While steps are taken to contain it from spreading, it cannot be eliminated completely.

How do antibiotics work?

Antibiotics target cellular machinery, specific to a bacteria, which is not normally present in the human cell. Hence, they kill the bacteria without affecting the patient in three ways:

  1. They affect the cell wall of the bacteria. Without the cell wall, the bacteria cannot maintain its integrity, and bursts. This is done by medicines called ‘beta-lactams’ like penicillin and carbapenems.
  2. They disrupt the mechanism by which bacteria make their proteins, which is required for them to function. ‘Macrolides’ like erythromycin and Tigecycline do this.
  3. They prevent the process of how DNA gets copied, which is required for reproducing, thereby stopping the bacteria from growing further. This what quinolones like ciprofloxacin and levofloxacin do.

Image illustrating Fighting the Superbugs

How does bacteria develop resistance?

The main points to keep in mind are:

  1. DNA mutations can happen spontaneously.
  2. Bacteria multiply fast

Hence, when an antibiotic is administered, while most bacteria die, the few that survive could either become resistant or develop resistance. These then multiply rapidly to occupy the space left by the other bacteria, thereby increasing the resistant population.

The scary part is that this resistance gene can also transfer from a bacterium to other families of bacteria of the same generation. This is called horizontal gene transfer. Like all living things, bacteria have DNA and genes that code for how the cell should function and more specifically, what proteins should be manufactured for its survival and growth. So if a bacteria gets the secret code (resistance gene) from its neighbour on how to escape an antibiotic, it will gladly accept it and use it.

The three main ways of gaining this piece of secret code is by:

  • swallowing it from the microenvironment from dead antibiotic resistant bacteria that have thrown out their genetic material.
  • transfer of the resistant gene through direct physical connections between the two bacteria
  • virus that first infects a bacteria resistant to antibiotics, carries the DNA with it and passes it on to the next bacteria it infects.

    Comic illustration of Plasmids

Nature, Furuya and Lowy (2006)

But what does it mean to get this resistant gene?

How does bacteria evade the antibiotic? Some of the techniques they use is – they spit out antibiotics, they modify or hide the site on which the antibiotic will act or they send out toxins that break the antibiotics.

This antibiotic resistance is happening at an alarming rate.

How can one be safe?

Avoid antibiotics unless it is a bacterial infection or doctors recommend it. Make sure to complete the course of antibiotics.

Discourage the use of antibiotics in food animals – if a bacteria affecting animals develops resistance, it can transfer that resistance to bacteria affecting humans. And most importantly, support research to develop new classes of antibiotics, hopefully a kind that is more sustainable and does not affect good bacteria.

Research and Awareness

A research published in July 2019 was conducted in India at the Indian Institute of Science and M.S. Ramaiah Medical College, Bangalore. They sought to find a molecule to fight Acinetobacter baumannii, a bacteria that has been put in the most critical section of the 12 deadliest drug resistant bacteria. Strains of this bacteria have been found to be resistant to even the last line of antibiotics, carbapenem- and tigecycline. The only other antibiotic available called colistin is known to cause a severe side effect of kidney failure.

Using computer models, the group identified a novel antimicrobial peptide (which is like a tiny protein) that they named Ω76. The most promising result of this work is that the peptide was able to kill carbapenem- and tigecycline resistant bacteria in mice with low toxic levels (unlike colistin). Ω76 works by damaging the cell wall of bacteria. This molecule will have to be tested further and go for clinical trials before it can be used as a reliable treatment alternative.

While research is being conducted to discover new antibiotics, immediate action is being taken by different initiatives in all countries. In Switzerland, campaigns to raise awareness among the public of proper use of antibiotics is being conducted. In India, a 2019 February published work talks about a surveillance tool being developed by the Indian Council of Medical Research to integrate information about antimicrobial resistance from participating laboratories and analyze the data in real time.

For a perspective of antibiotics from a Science policy maker with an interesting analogy to the energy sector, check this TED-ED talk by Ramanan Laxminarayan

Please leave comments/questions below, along with suggestions on other topics that you would like me to cover.

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