Antibiotic resistance: the scientific apocalyptic scenario

Caught a minor infection? Go get your miracle cure, antibiotics, from your local doctor’s office now! Receiving an antibiotic treatment seems so self-evident in modern day society, to a point that common infections are considered as harmless. But what happens if our miracle cure loses its effect?

That urinary tract infection that keeps coming back every year or that pulmonary infection you can’t quite shake off suddenly turn into something very dangerous and potentially deadly.

This sounds like a terrifying scenario.

A terrifying and real scenario.

It turns out that bacteria have caught up to our achievements in modern medicine. Many harmful bacteria have developed resistance against antibiotics. Antibiotic resistant bacteria no longer respond to drugs to which they were originally sensitive to making it harder or even impossible to cure.

What is antibiotic resistance

Antibiotic resistance is when a bacteria develops a way to incapacitate a certain antibiotic. There are four main mechanisms by which this can be achieved. The drug can be inactivated or modified by the bacteria making it harmless, the target site of the antibiotic can be altered thereby preventing the drug from binding, The bacterium can change its own metabolism to make the antibiotic target redundant for cell survival, or the antibiotic can be actively pumped out of the cell before it is able to cause any harm.

Bacteria have two ways to acquire resistance.
Bacteria are able to genetically mutate and acquire a change in the binding site of antibiotics. The bacteria is then less susceptible to the drug. This mutation is the past on to all further descendants. Although mutation occur only once in every ten billion replications, the high reproduction rate of bacteria cause this effect to still be significant.

Figure 1: Antibiotic targets and acquiring resistance

Resistance to antibiotics can also be caused by horizontal gene transfer where a resistance gene is transferred from one bacteria to another. This can happen between and within the same species. These transfers takes place by means of a special gene transfer mechanism. Most antibiotic genes are located on what is known as a plasmid. This is a small circular piece of DNA that can be easily copied and transferred through cell-cell contact via a pilus. The gene can also be transferred by bacteriophages (viruses that infect bacteria), or even release and uptake of DNA in

extracellular fluids.

Figure 2: Three ways of gene transfer between bacteria

Antibiotic resistance isn’t free

Although it seems that antibiotic resistance is of pure benefit to the bacteria, keeping itself safe from antibiotics comes with a cost. Acquiring antibiotic resistance costs energy and often interferes with normal bacterial processes. Resistance therefore comes with a fitness cost. Overall resistant bacteria are ‘weaker’ than their normal counterparts. However, this changes when the antibiotic is present.

Bacteria that carry a plasmid or mutation are better adapted to an environment where antibiotics are present, like your body during an antibiotic treatment. Following Darwin’s age old rule, survival of the fittest, the adapted bacteria survive, live and reproduce while the others die. This ultimately leads to a resistant colony.

That is when it becomes dangerous. Your suddenly faced with an infection that cannot be cured through the usual treatment. Furthermore you are an infection source for other people. 

Then why not treat it with another antibiotic?

This should of course be the usual course of action. However, most of the common bacteria strains have developed resistance to multiple antibiotics, making them incredibly hard to cure. For example, staphylococcus aureus strains (MRSAs) have developed resistance for multiple antibiotic agents due to its extreme pressure to adapt to antibiotics. MRSAs are therefore one of the most common causes of hospital-acquired infections infecting around 500.000 and killing about 11.000 patients in US hospitals alone.

how widespread is antibiotic resistance at the moment?

The World Health Organization (WHO) issued a global report in June 2014 on the magnitude and current surveillance of the spread. It has been observed that alarmingly high rates of resistance the seven most common pathogenic bacteria, such as E. coli, Salmonella and S. aureus, have been found throughout the world. The report also stated that tools to battle antibiotic resistant were often lacking or non-excitant in many countries. The threat was in fact so severe that a global action plan was installed to tackle actions that accelerate antibiotic resistance.  If we keep using antibiotics inappropriately and do not properly prevent and control infection, many medical treatments will fail and make common infections deadly again.

What can I do to prevent the apocalypse?

Antibiotic resistance is a complex problem, but you can be part of the solution. Small efforts like washing your hands, avoiding contact with sick people and getting vaccinated go a long way if they are applied by everyone. And when it comes to antibiotics: use only when prescribed by a doctor, always complete your treatment and never share your leftover drugs.

Coen Hanselaar