Antibiotic resistance driven by intragenomic co-evolution

July 25, 2017 by Alistair Keely, University of York
Antibiotic resistance – gaining resistance is just the start
Different coloured proteins allow scientists to carry out 'bacterial time travelling'. Credit: University of York

Scientists have discovered bacteria are able to "fine-tune" their resistance to antibiotics – raising the possibility of some superbugs being resistant to drugs which they have never even been in contact with.

Bacteria can become resistant to in several ways. One really fast and effective way is by gaining extra DNA, called a , from other .

The plasmid provides bacteria with the genes needed to become resistant to specific antibiotics.

E.coli

Scientists know that in hospitals bacteria can spread through these plasmids, but don't know much about how the plasmids and the bacteria form a relationship with each other.

Using a technique called experimental evolution, the scientists from the Universities of York and Sheffield, controlled the environment the E. coli were exposed to and allowed them to grow and evolve.

The bacteria were grown for 80 days (about 530 generations) exposing them continuously to an antibiotic.

During the 80 days the bacteria were exposed to the antibiotic, first they gained additional resistance mutations themselves, but this meant that the resistance provided by the plasmid was now somewhat redundant and could therefore be tuned down.

This produced a plasmid and host that were now dependent upon each other when exposed to this antibiotic.

First author Michael Bottery, from the University of York's Department of Biology, said: "Gaining resistance plasmids is just the start of the bacteria's journey to become resistant; the marriage between plasmid and bacteria is a complex one, involving both compromise and changes in behaviour.

"It is a relationship we need to unpick further in order to best preserve the use of the antibiotics we have for use in both critical and routine medical procedures.

"The experiment has shown that if you stop giving antibiotics, resistance won't go away. If you keep using the same antibiotics the bacteria will just get better and better by fine-tuning their resistance.

"And we have also shown if you give the same antibiotic over and over again it could also become resistant to completely different antibiotics which they have never seen before."

Co-dependent

Dr Jamie Wood, Senior Lecturer in Biological Modelling at York added: "The hosts have taken advantage of the plasmid resistance to evolve their own resistance and become co-dependent on each other.

"What we are really showing here is the relationship between the bacteria and these plasmids is a really complicated situation and we might be able to find better ways of managing it.

"Antibiotic resistance is a huge global threat - the UN has put it as equal threat as climate change.

"We need to gain this kind of basic scientific understanding of how bacteria become resistant, but also how they maintain resistance and how resistance changes over time."

Explore further: Antibiotic resistance—it's a social thing

More information: Michael J. Bottery et al. Adaptive modulation of antibiotic resistance through intragenomic coevolution, Nature Ecology & Evolution (2017). DOI: 10.1038/s41559-017-0242-3

Related Stories

Antibiotic resistance—it's a social thing

March 15, 2016

Trace concentrations of antibiotic, such as those found in sewage outfalls, are enough to enable bacteria to keep antibiotic resistance, new research from the University of York has found. The concentrations are much lower ...

New mechanism to fight multi-resistant bacteria revealed

April 19, 2017

In recent years, scientists, clinicians and pharmaceutical companies have struggled to find new antibiotics or alternative strategies against multi-drug resistant bacteria that represent a serious public health problem. In ...

Bacteria in estuaries have genes for antibiotic resistance

January 31, 2017

An international group of researchers, including Professor Michael Gillings from Macquarie University, have reported that pollution with antibiotics and resistance genes is causing potentially dangerous changes to local bacteria ...

Recommended for you

A world of parasites

May 25, 2018

Alex Betts, Craig MacLean and Kayla King from the Department of Zoology, shed light on their recent research published in Science, which addressed the impact that parasite communities have on evolutionary change and diversity.

A better B1 building block

May 25, 2018

Humans aren't the only earth-bound organisms that need to take their vitamins. Thiamine – commonly known as vitamin B1 – is vital to the survival of most every living thing on earth. But the average bacterium or plant ...

Plant symbioses—fragile partnerships

May 25, 2018

All plants require an adequate supply of inorganic nutrients, such as fixed nitrogen (usually in the form of ammonia or nitrate), for growth. A special group of flowering plants thus depends on close symbiotic relationships ...

Bumblebees confused by iridescent colors

May 25, 2018

Iridescence is a form of structural colour which uses regular repeating nanostructures to reflect light at slightly different angles, causing a colour-change effect.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

HenryE
not rated yet Jul 25, 2017
How do the bacteria get the plasmids from other bacteria? Do they consume other bacteria, or is there a mechanism by which some bacteria provide DNA segments for others?

Also, how do they incorporate the new DNA into their genome?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.