Scientists discover antibiotic-eating germs

Apr 07, 2008

SEVERAL strains of bacteria in the soil can make a meal of the world’s most potent antibiotics, researchers said last week. The startling finding illustrates the extent to which these germ-fighting drugs are losing the war against bacteria.

SEVERAL strains of bacteria in the soil can make a meal of the world’s most potent antibiotics, researchers said last week. The startling finding illustrates the extent to which these germ-fighting drugs are losing the war against bacteria.

A study of soil microbes taken from 11 sites discovered bacteria that could withstand antibiotics 50 times stronger than the standard for bacterial resistance.

“It certainly was very surprising to us,”said George Church, a geneticist at Harvard Medical School in Boston, whose research appears in the journal Science.

“Many bacteria can not only tolerate antibiotics, they can actually live on them as their sole source of nutrition,” Church said in an interview on the journal's web site.

Other researchers have found antibiotic-eating strains of bacteria, but Church's study is among the most systematic. It offers more clues about why bacteria quickly develop resistance to antibiotics, and why drug companies must constantly develop new antibiotics to defeat them.

Church’s team initially set out to find organisms in the soil that remove toxins from cellulose, the material that gives plants structure.

Bacteria taken from soil samples could easily defeat toxins from cellulose. The researchers then tested the microbes against antibiotics, something they thought would be toxic.

“We were expecting them to grow on cellulose and we weren’t expecting them to grow on antibiotics,” Church said.

Surprised by how easily the microbes devoured the antibiotics, Church and colleagues did a broader test, exposing hundreds of microbes to 18 antibiotics representing most of the major classes of naturally-occurring and synthetic antibiotics, including penicillin and ciprofloxacin.

“We could find bacteria that could grow on almost all of them, depending on the bacteria and the source of the soil,” Church said.

The bacteria were not known to attack humans, but some were close relatives; the type that infect people with cystic fibrosis, and those that cause blood infections.

The research showed that the microbes could be using a new way to disarm the antibiotics, but it may take some time to figure that out.

Church said the finding underscores the extent to which bacteria have developed resistance to antibiotics, a process that started almost as soon as penicillin was introduced in the 1940s. Over prescription and misuse of antibiotics have fuelled the rise of drug-resistant bacteria.

One antibiotic resistant infection killed 19,000 people in the US in 2005.

Reuters

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