The growth of bacteria can be stimulated by antibiotics, scientists have discovered.

The EPSRC-funded researchers exposed E.coli bacteria to eight rounds of antibiotic treatment over four days and found the bug — which can cause severe stomach pain, diarrhea and kidney failure in humans — had increased antibiotic resistance with each treatment.

This had been expected, but researchers were surprised to find mutated E.coli reproduced faster than before encountering the drugs and formed populations that were three times larger because of the mutations.

This was only seen in bacteria exposed to antibiotics — and when researchers took the drug away, the evolutionary changes were not undone and the new-found abilities remained.


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“Our research suggests there could be added benefits for E.coli bacteria when they evolve resistance to clinical levels of antibiotics,” said lead author Professor Robert Beardmore, of the University of Exeter.

“It’s often said that Darwinian evolution is slow, but nothing could be further from the truth, particularly when bacteria are exposed to antibiotics.

The researchers tested the effects of the antibiotic doxycycline on E.coli as part of a study of DNA changes brought about by antibiotics.

Read the full press release here.

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