RISPR-Cas9: A weapon against antibiotic-resistant superbugs?


Before the discovery of penicillin in 1928, even common infections such as sore throat could be a fatal diagnosis. Antibiotics gave us a great advantage in the fight against harmful bacteria. Since then, antibiotics have improved significantly. But so are bacteria.

The rapid rise in antibiotic resistance is one of the most serious health problems in the world, killing about 700,000 people every year, according to the WHO. A 2018 study found that these so-called superbugs are responsible for 33,000 deaths annually in the EU alone.

The development of new antibiotics has slowed down and are struggling to keep up with resistant bacteria.

Good bacteria versus evil bacteria

In a recent study, researchers managed to kill resistant bacteria in the intestines of mice. This technique, which is still being researched, uses the famous Nobel Prize-winning gene editing technology, CRISPR-Cas9.

Scientists at the University of Sherbrooke in Canada have used technology that works like “genetic scissors” to penetrate resistant bacteria and cut the vital genetic strands that shut off the bacteria by killing them from the inside.

This result is promising not only because the bacteria were successfully killed, but also because it specifically targeted bad bacteria rather than killing a whole bunch of good bacteria along with bad ones, which antibiotics do.

But what is CRISPR-Cas9?

Imagine you have a book from which you want to remove a specific sentence. You have a small device that can search a book for an exact sentence and extract it without damaging the book. On a computer, it would be like using the search function (Ctrl + F) to identify and remove the specified text. This is pretty much what CRISPR-Cas9 does, only on a much smaller scale – it just replaces the book with a DNA or RNA sequence.

It is like a molecular searching and cutting machine. You give him the target DNA sequence and he will cut exactly and only there. In this case, it is the DNA sequence belonging to the antibiotic resistance gene.

In theory, this seems straightforward. But putting this molecular machine inside resistant bacteria isn’t easy. Canadian researchers managed to do this by using a curious thing that bacteria are capable of. When in contact, they can transfer genetic material to each other. The process is called pairing. It’s like being able to send files from one smartphone to another by touching them.

These scientists used CRISPR-Cas9 to target an antibiotic resistance gene and modified it to be easier to transfer between bacteria. Then they placed it inside harmless bacteria and fed it to the mice. Surprisingly, it killed over 99.9% of the targeted antibiotic-resistant bacteria in just four and four days.

While CRISPR-Cas9 is a very powerful and accurate tool that could potentially be very useful in eliminating antibiotic resistance, researchers still don’t know if bacteria are also capable of developing resistance to this technology.

But this is just one example of a multitude of studies in this area. Some research groups have used bacteria attacking viruses called bacteriophages as vehicles, while others have targeted bacterial RNA instead.

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