What causes antibiotic resistance?

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Most of us will have taken antibiotics at some point in our lives. But what if nothing happens the next time you pop one of those little bug-busting pills? Your life could be in serious danger.

Bacteria are an integral part of our ecosystem and we share our bodies with many of these tiny creatures. However, they can be the root of serious health problems.

There are roughly as many human cells as bacterial cells in our bodies, and our microscopic passengers pay their way by helping our immune system and contributing to our metabolism.

But bacteria come in all manner of guises. Some can turn from friend to foe, while others are just plain nasty and will make us sick at any chance they get.

Since their discovery in the 1920s and their introduction into mainstream medicine after World War Two, we’ve been relying on antibiotics to keep pathogenic bacteria at bay.

Antibacterial resistance is on the rise, however. According to the Centers for Disease Control and Prevention (CDC), each year in the United States, at least 2,049,442 illnesses are caused by resistance to medicines prescribed to treat bacterial or fungal infections. What is more, 23,000 people die each year when these drugs fail to work.

So, why have our once reliable antibacterials stopped working, and how do the pesky bugs manage to outfox us? It’s all about mutations.

Mutations, a ‘natural phenomenon’

Bacteria are prone to DNA mutations. This is part of their natural evolution and allows them to constantly adapt their genetic makeup. When one bug naturally becomes resistant to a drug, it survives when all others are killed.

Now it’s a race against the clock.

How quickly can this one bacterium adapt to the new mutation, and how quickly can it replicate in the face of species eradication? If the bug comes on out top, it’s bad news for the infected individual and bad news for society at large: the drug-resistant bacterium will likely spread.

Not only has it evaded the grim reaper, but it can also now spread the love by passing the resistance to its numerous offspring, who will soon be the dominant species on the block.

Bacteria are also able to pass genes to other bacteria. This is known as horizontal gene transfer, or “bacterial sex.” While this process is actually quite rare, bacteria are highly mobile creatures, which gives them plenty of opportunity to come into contact with other microbes and pass on their mutated genes.

But how do genetic mutations equip bacteria with the skills to outsmart antibiotics?

Combating antibiotics

A study recently published in Nature Communications sheds new light on how Echerichia coli and other members of the Enterobacteria family fight off commonly used antibiotics.

A gene called mar is commonly shared by family members. Some of the proteins encoded in this gene can switch on other genes, explain researchers from the University of Birmingham’s Institute of Microbiology and Infection in the United Kingdom.

“We found two completely unexpected mechanisms,” says senior study author Prof. David Grainger, “that bacteria use to protect themselves from antibiotics. One protected their DNA from the harmful effects of fluoroquinolone antibiotics, and the other prevented doxycyline getting inside bacteria.”

But finding out how Enterobacteria combat antibiotics is only the first step in this decade-long research project.

First study author Prateek Sharma, Ph.D., says that “the resistance mechanisms that we identified are found in many different species of bacteria therefore, our research could lead to the discovery of molecules that could be developed into new drugs that can treat bacterial infections.”

The World Health Organization (WHO) call antibiotic resistance “one of the biggest threats to global health, food security, and development today.” The need for new drugs is great.

‘Overuse and underuse’ of antibiotics

This week is World Antibiotic Awareness Week. The WHO aim to warn people that inappropriate use of antimicrobials makes drug resistance worse. This includes both overuse and underuse.

This year, they urge everyone to “[s]eek advice from a qualified healthcare professional before taking antibiotics.”

To find out more, here is video from the WHO explaining why they think that “everyone has a role to play to help reduce antibiotic resistance.”

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