Health Lifestyle

Antibiotics cause bacteria to mutate, grow faster

Antibiotics cause bacteria to mutate, grow faster

Antibiotics may cause bacteria to mutate into “uberbugs” which reproduce much faster, say scientists who found that a bug which causes severe stomach pain, diarrhoea and kidney failure in humans had increased resistance after each round of drug treatment.

Researchers at University of Exeter in the UK exposed E coli bacteria to eight rounds of antibiotic treatment.

They found that mutated E coli reproduced faster than before en countering 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 evolutionary changes were not undone. “Our research suggests there could be added benefits for E coli bacteria when they evolve resistance to clinical levels of antibiotics,” said prof Robert Beardmore of University of Exeter.

“Bacteria have a remarkable ability to rearrange their DNA and this can stop drugs working, sometimes in a matter of days,” he said. “While rapid DNA change can be dangerous to a human cell, to a bacterium like E coli it can have multiple benefits, provided they hit on the right changes,” he added.

The researchers tested the effects of the antibiotic doxycycline on E coli as part of a study of DNA changes brought about by antibiotics. The E coli “uber-bug” that subsequently evolved was safely frozen at -80°C and the scientists used genetic sequencing to find out which DNA changes were responsible for its unusual evolution.

“Our best guess is that losing viral DNA stops the E coli destroying itself, so we see more bacterial cells growing once the increase in pump DNA allows them to resist the antibiotic,” said Carlos Reding, from University of Exeter.