How can we combat antibiotic resistance?

Since the first use of penicillin in 1942, antibiotic resistant bacteria have started to evolve. Usually, resistance develops quickly (a few years after drug introduction). This means that bacterial infections that once were benign could become deadly (back to how bacterial infections were prior to antibiotics). However, there are a few plans that could help combat the threat of bacterial infections.

If you could like to read about what antibiotic resistance is, read this article I wrote:

The most obvious way to get antibiotics is from nature itself. Microbes (other bacteria and fungi) have developed their own antibiotics in order to survive in a competitive environment. If there are many microbe species in a population, the species will have to compete for nutrients and space. This is called interspecific competition (competition for resources between different species). As a result, many microbes have evolved to kill or inhibit growth of their competition in an attempt to “win” and survive. These chemicals can be utilised as antibiotics that can treat bacterial infections.

However, there is an obvious problem with this method. Due to the consistent prescription and overuse of antibiotics (specifically in agriculture), antibiotic resistance would develop again in any new form of drug developed. Bacteria would evolve to be resistant to these new antibiotics. The prospect of a new drug becoming useless after a year of introduction is not appealing to pharmaceutical companies that are attracted to profits (the cost of drug production and clinical trails is too high for the drug to be discontinued after antibiotic resistance develops against it). As a consequence, pharmaceutical companies are not investing in finding antibiotics anymore. Less funding means less scientific discoveries.

A second way that scientists are tackling bacterial infections are bacteriophages. Bacteriophages are viruses that engulf bacteria. Viruses are able to attack bacteria and the benefit is that the bacteriophages can not infect human cells. This allows us to utilise viruses to kill bacteria. Here is a more detailed explanation on how bacteriophages infect bacteria:

Another way to kill bacteria is to add another molecules to antibiotics. Bacteria gain resistance to existing antibiotics due to the proteins it produces. These proteins can act in many forms. Some act as pumps that pump antibiotics out of the bacterial cell before it can kill the bacterium. However, scientists are developing molecules that can block these proteins, thus ensuring the delivery of the antibiotics.

The last method I will mention relies on how bacteria “talk” to each other. Bacteria are so small, therefore, individual cells they can not cause too much damage in the human body. However, when the bacteria work together as a colony, they are able to co ordinate their attacks and release the toxins that make humans ill. Scientists call the communication between bacteria quorum sensing.

There are 2 types of quorum sensing both of which involves the bacteria secreting small molecules called auto inducers. When there are not many bacteria around, the auto inducers have no affect and are dilute. But when there are many bacteria in a space, the concentration of auto inducers increases. The inducers bind to receptors on the bacteria, triggering a response. The inducers signal “Hey, your friends are here. Attack together!”. Consequently, the bacteria all secret toxins and infect our human cells at the same time which overwhelms our immune systems and makes us sick.

The two types of quorum sensing are:

  • Intraspecies communication = communication between bacteria of the same species. They have specific auto inducers that only one species can recognise
  • Interspecies communication = communication between bacteria of different species. Scientists have found out that bacteria have universal auto inducers that allow them to communicate with other microbes in the environment.
Photo from The Guardian. Bacteria often live in very diverse environments (our own gut being a good example). The bacteria are able to communicate with one another to create an ecosystem of bacteria known as our microbiome.

So how does this help us with antibiotic resistance? Now we know how bacteria launch an attack (and increase their virulence) we can stop it. Therefore, scientists are creating anti-quorum sensing molecules that lock into receptors and stop recognition of auto inducers. This will not kill bacteria but will ensure they do not function as well and will have less of a effect on our larger bodies (compared with their microscopic size).

Photo from The London School of Economics

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