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Bacteria which lie dormant and impervious to antibiotics could be activated briefly before being killed off, say scientists.

Dormant E. coli bathed in nutrients in the lab were transformed for a few hours into a vulnerable, active state.

Israeli researchers, reporting in Proceedings of the National Academy of Sciences, say this might be the best time for treatment.

However, a British expert said the approach was "fraught with risks".

Some bacteria are hard to treat because even large doses of antibiotics cannot clear the infection, with large numbers in an inactive state inside or outside cells.


It could be a bit like awakening a sleeping giant
Professor Michael Brown
University of Wolverhampton

When conditions are right, these dormant bacteria have the ability to reawaken and start to divide and spread once more.

The best known of these is tuberculosis, and infected patients are given courses of drugs which last for many months to try to eradicate it, raising the risk both of the bacterium gaining resistance to the drugs, and of the patient failing to observe the drug regime.

The researchers from The Hebrew University in Jerusalem believe that there may be a way to boost the effectiveness of antimicrobial drugs against dormant bacteria, by introducing a precisely-timed dose.

By measuring, in real-time, the chemicals produced, they proved that dormant E. coli bacteria bathed in a nutrient-rich broth sprung back to life, but only for a single hour.

Shortly afterwards, they returned to their dormant state, and could survive a five-hour dose of antibiotics.

Human difference

While this was observed in the laboratory, so far the researchers have not created the same conditions in a human being to test their theory, or tested to see if the same effect could be produced in the laboratory using other bacteria, including TB.

Professor Michael Brown, a microbiologist from the University of Wolverhampton, said there were practical difficulties in aiming for a similar effect in humans.

If the large numbers of dormant bacteria in a patient could be sparked to life at once, he said, this might well be counterproductive.

"It could be a bit like awakening a sleeping giant," he said.

"Even if you could bring all these bacteria out of dormancy, I don't believe that antibiotics or the patient's own immune system would be capable of eradicating them all."

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