Bacteria evolve resistance more quickly when stronger antibiotics are used

Apr 23, 2013
Researchers from the University of Exeter and Kiel University in Germany treated E. coli with different combinations of antibiotics in laboratory experiments. Unexpectedly they found that the rate of evolution of antibiotic resistance speeds up when potent treatments are given because resistant bacterial cells flourish most during the most aggressive therapies. Credit: Kiel University

New scientific research published today in the journal PLoS Biology shows that bacteria can evolve resistance more quickly when stronger antibiotics are used.

Researchers from the University of Exeter and Kiel University in Germany treated E. coli with different combinations of antibiotics in laboratory experiments.

Unexpectedly they found that the rate of evolution of antibiotic resistance speeds up when potent treatments are given because resistant flourish most during the most aggressive therapies.

This happens because too potent a treatment eliminates the non-, creating a lack of competition that allows to multiply quickly. Those cells go on to create copies of resistance genes that help them rapidly reduce the effectiveness of the drugs. In tests this effect could even cause E.coli to grow fastest in the most aggressive .

In addition to evolution experiments, the results of this Engineering and Physical Sciences Research Council (EPSRC) and Medical Research Council (MRC) funded research were confirmed using mathematical models and whole-genome sequencing of resistant and non-resistant E. coli.

Professor Robert Beardmore, EPSRC Research Fellow from the University of Exeter said: "We were surprised by how quickly the bacteria evolved resistance. We nearly stopped the experiments because we didn't think some of the treatments should be losing potency that fast, sometimes within a day. But we now know that the bacteria remaining after the initial treatment have duplicated specific areas of their genome containing large numbers of . These gene copies appear more quickly when the antibiotics are combined, resulting in the of very resistant bacteria.

"Designing new treatments to prevent antibiotic resistance is not easy, as this research shows, and governments may need to increase their funding for antibiotics research if scientists are to be able to keep pace with the rapid evolution of bacterial pathogens that cause disease."

Dr Rafael Pena-Miller from Biosciences at the University of Exeter said: "The evidence that combining antibiotics to make a more potent therapy can lead to the creation of more copies of the genes the bacteria needs to be resistant is of real concern."

Professor Hinrich Schulenberg from Kiel University in Germany said: "The interesting thing is that the bacteria don't just make copies of the genes they need. Just in case, they copy other genes as well, increasing resistance to antibiotics the cells weren't even treated with."

About 440 000 new cases of drug-resistant tuberculosis emerge annually, causing around 150 000 deaths. Statistics like this recently lead the Department of Health to state that antibiotic resistance poses one of the greatest threats to human health.

Explore further: How a molecular Superman protects the genome from damage

Related Stories

Resistant gut bacteria will not go away by themselves

Jun 19, 2007

E. coli bacteria that have developed resistance to antibiotics will probably still be around even if we stop using antibiotics, as these strains have the same good chance as other bacteria of continuing to colonise the gut, ...

'Stressed' bacteria become resistant to antibiotics

Feb 21, 2013

Bacteria become resistant to antibiotics when stressed, finds research published in BioMed Central's open access journal BMC Evolutionary Biology. In particular E. coli grown at high temperatures become resistant to rifampicin ...

Tracking the evolution of antibiotic resistance

Feb 01, 2013

With the discovery of antibiotics, medicine acquired power on a scale never before possible to protect health, save lives, and reduce suffering caused by certain bacteria. But the power of antibiotics is now under siege because ...

Roads pave the way for the spread of superbugs

Sep 29, 2011

Antibiotic resistant E. coli was much more prevalent in villages situated along roads than in rural villages located away from roads, which suggests that roads play a major role in the spread or containment of antibiotic resist ...

Recommended for you

Cell architecture: Finding common ground

Oct 16, 2014

When it comes to cellular architecture, function follows form. Plant cells contain a dynamic cytoskeleton which is responsible for directing cell growth, development, movement, and division. So over time, changes in the cytoskeleton ...

Scientists identify "naïve-like" human stem cell

Oct 16, 2014

Scientists from our university and Berlin have identified a type of human stem cell that appears to be "naïve-like" – able to develop into any type of cell. The discovery of this cell type could potentially ...

Shaping the way to see the world

Oct 16, 2014

The proliferation of cells, in particular the orientation in which they divide, is key in regulating the shapes of tissues. However, the cellular mechanisms that govern cell proliferation and cell division orientation are ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

KnowledgeAndTruth
not rated yet Apr 24, 2013
Is this surprising at all?! Stronger selection leads to quicker fixation of advantageous alleles! And this concept has been around for decades! To avoid being misunderstood, I must clarify that I am not claiming that the particular discovery of the molecular mechanisms in this study is redundant. The research is genuine, we learnt new stuff. However, the title of the post is mis-focused and exaggerates a supposed unexpectednes, which is not the case.