Antibiotics have saved countless lives over the decades. But despite the pathogens they kill, antibiotics are an old enemy, one they are already familiar with fighting.
It turns out that antibiotic resistance may not be as limited as we assumed, with easier access to more antibiotic – resistant strains than previous models would have us believe.
The findings come from a study conducted by bioinformatics researcher Jan Zrimec from Chalmers University of Technology in Sweden, which looked for movement signals among elements of DNA called plasmids.
If a genome were a cookbook, plasmids could be imagined as scattered pieces of paper with precious recipes stolen from friends and relatives. Many contain instructions for making products that help bacteria survive under stressful conditions.
And for bacteria, a dose of antibiotics is around as much weight as it gets.
While we have been using them as a form of medicine for the better part of a century, the fact is that we have just been inspired by a microbial weapon race that may be almost as old as life. yourself.
As different species of microbe have decided on new ways to inhibit the growth of their bacterial competitors over the centuries, bacteria have found new ways to overcome them.
These protective measures are often retained in plasmid coding, allowing bacterial cells to divide through a process called co-evaluation. If that word awakens thoughts of encounters when you visit prisons, you need to stretch your imagination a little further to paint a picture of it … between single-celled organisms.
For plasmids to be widely distributed between cells in the action of a bacterial hanky-panky, they need a division of genetic coding called origin–de–motion sequence, or oriT.
It is this enzyme-borne layer that slices the open plasmid for easy copying, and then seals it again. Without oriT, plasmid’s secret recipe intends to remain in its owner’s possession.
In the past, it was believed that each plasmid had to have both oriT and code for the enzyme in order for it to be shared in binding functions.
Today, it is clear that the enzyme is not unique in a particular oriT sequence, meaning that if a bacterial cell contains several plasmids, some may benefit from the enzymes encoded by others .
If we want to create a shareable catalog of plasmids – including those that contain instructions on antibiotic resistance – we need to know how many oriT series there are.
Unfortunately, finding and measuring these layers is a time-consuming and labor-intensive task. Zrimec has therefore developed a much more efficient way to detect oriT based on specific features of the physical properties of the encoding.
He submitted his findings to a database of more than 4,600 plasmids, measuring how common mobile plasmids were based on oriT frequency.
We seem to have been far off the mark in terms of the prevalence of this essential series, with Zrimec results eight times higher than previous estimates.
Taking into account other motive factors, it could mean that there are twice as many mobile plasmids among bacteria as we thought, with twice as many bacterial species. And that’s not it.
There was one other discovery made by Zrimec that is worrying.
“Plasmids belong to different movement groups, or MOB groups, so they can’t move between just any bacterial species,” Zrimec says.
But his research now suggests half of the oriT sequences he found were an appropriate binding enzyme from a completely different MOB group, suggesting that the boundaries between bacterial species may be more blurred. circulating to plasmids what we thought too.
All this is troubling news due to the race to develop new antibacterial treatments.
“These results could lead to a strong network for the transfer of plasmids between bacteria in humans, animals, plants, soil, aquatic environments and industries, to name a few,” Zrimec said.
“Protective genes occur naturally in many different bacteria in these ecosystems, and the neural network could mean that genes from all of these environments can be transferred to bacteria. which causes disease in humans. “
It’s a weapon race we launched to save lives – without ever thinking about how capable bacteria would be in matching our firepower.
Technology like this will help us to better understand what we are doing. And already, it doesn’t look good.
This research was published in Open Microbiology.