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Friday 25th May 2018

Antibiotic-eating germs found

7th April 2008

Researchers in the United States have found several strains of bacteria in soil samples that are not only resistant to antibiotics: they actually feed on them.


Geneticist George Church of the Harvard Medical School said his team was very surprised to find bacteria that could withstand antibiotics up to 50 times stronger than the standard used to judge bacterial resistance to the germ-fighting drugs.

The study, published in the journal Science, looked at soil microbes taken from 11 sites. It found that many bacterial in many different soil isolates could not only tolerate antibiotics; they can actually live on them as their sole source of nutrition.

While antibiotic-eating bacteria are not entirely new, Church's study is the first to study them systematically, offering clues about why bacteria develop resistance to antibiotics so quickly.

The phenemenon of drug resistance is causing increasing concern among global health experts, as drug companies struggle to develop new antibiotics to defeat increasingly resistant strains of bacteria.

Church's team took samples from a variety of sites, including a cornfield fertilised by manure from cows that were fed antibiotics.

Initially they had set out to find organisms in the soil that remove toxins from cellulose, and they found them easily, as expected.

However, when they tested the microbes against antibiotics, which they believed would be toxic to them, the bacteria devoured them easily.

The research team were surprised by these findings, and did a broader series of tests exposing hundreds of microbes to 18 separate antibiotics, including the major classes of synthetic and naturally occurring antibiotics currently in use. These included ciprofloxacin and penicillin.

Depending on the bacterial and the source of the soil samples, the team found bacteria that could grow on almost all of them.

These bacteria were not of a kind that is known to infect humans, but they did include close relatives of the Burkholderia cepacia complex, which infects people with cystic fibrosis, and Serratia marcescens, which can cause blood infections in people with compromised immune systems.

Overuse and misuse of antibiotics have fuelled the rise in drug-resistant superbugs, but the process began as soon as antibiotics were discovered in the 1940s.

Church said the study could provide new perspectives on resistance, and that further research was needed to work out whether the bacteria had developed new ways of disarming the antibiotics.

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