amazing...
http://www.sciencemag.org/cgi/content/full/320/5872/100
http://www.sciencemag.org/cgi/content/full/320/5872/33a
http://www.sciencemag.org/cgi/content/full/320/5872/100
Science 4 April 2008:
Vol. 320. no. 5872, pp. 100 - 103
DOI: 10.1126/science.1155157
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Reports
Bacteria Subsisting on Antibiotics
Gautam Dantas,1* Morten O. A. Sommer,1,2* Rantimi D. Oluwasegun,1 George M. Church1{dagger}
Antibiotics are a crucial line of defense against bacterial infections. Nevertheless, several antibiotics are natural products of microorganisms that have as yet poorly appreciated ecological roles in the wider environment. We isolated hundreds of soil bacteria with the capacity to grow on antibiotics as a sole carbon source. Of 18 antibiotics tested, representing eight major classes of natural and synthetic origin, 13 to 17 supported the growth of clonal bacteria from each of 11 diverse soils. Bacteria subsisting on antibiotics are surprisingly phylogenetically diverse, and many are closely related to human pathogens. Furthermore, each antibiotic-consuming isolate was resistant to multiple antibiotics at clinically relevant concentrations. This phenomenon suggests that this unappreciated reservoir of antibiotic-resistance determinants can contribute to the increasing levels of multiple antibiotic resistance in pathogenic bacteria.
1 Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
2 Program of Biophysics, Harvard University, Cambridge, MA 02138, USA.
Vol. 320. no. 5872, pp. 100 - 103
DOI: 10.1126/science.1155157
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Reports
Bacteria Subsisting on Antibiotics
Gautam Dantas,1* Morten O. A. Sommer,1,2* Rantimi D. Oluwasegun,1 George M. Church1{dagger}
Antibiotics are a crucial line of defense against bacterial infections. Nevertheless, several antibiotics are natural products of microorganisms that have as yet poorly appreciated ecological roles in the wider environment. We isolated hundreds of soil bacteria with the capacity to grow on antibiotics as a sole carbon source. Of 18 antibiotics tested, representing eight major classes of natural and synthetic origin, 13 to 17 supported the growth of clonal bacteria from each of 11 diverse soils. Bacteria subsisting on antibiotics are surprisingly phylogenetically diverse, and many are closely related to human pathogens. Furthermore, each antibiotic-consuming isolate was resistant to multiple antibiotics at clinically relevant concentrations. This phenomenon suggests that this unappreciated reservoir of antibiotic-resistance determinants can contribute to the increasing levels of multiple antibiotic resistance in pathogenic bacteria.
1 Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
2 Program of Biophysics, Harvard University, Cambridge, MA 02138, USA.
Science 4 April 2008:
Vol. 320. no. 5872, p. 33
DOI: 10.1126/science.320.5872.33a
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News of the Week
MICROBIOLOGY:
Germs Take a Bite Out of Antibiotics
Mitch Leslie
As far as patients and doctors are concerned, bacteria are supposed to do one thing when they encounter antibiotics: drop dead. But a broad survey of soil microbes shows that numerous species devour even the most potent drugs. The craving for antibiotics is widespread across environments and bacterial groups, researchers report on page 100, fueling worries about the dwindling power of our main weapons against infections.
Although a few previous studies had identified antibiotic-eating strains, "nobody had done a systematic search like this," says chemical biologist Gerry Wright of McMaster University in Hamilton, Canada. "It's one of those papers that unveils a whole new area of research."
Eighty years after Alexander Fleming discovered penicillin on a moldy culture dish, the battle against killer bugs is faltering. More and more bacteria--including insidious tuberculosis strains that have cropped up (Science, 15 February, p. 894)--now shrug off almost all antibiotics. Meanwhile, few new antibiotics are reaching the clinic. Medicine is on the defensive, says microbiologist and physician Stuart Levy of Tufts University School of Medicine in Boston. "We are not keeping up with the bacteria."
Geneticist George Church of Harvard Medical School in Boston and colleagues had not planned to dig up more grim news about antibiotics. These researchers were hunting for microbes that could convert agricultural waste into biofuels and were using antibiotics in their control studies. But for some bacteria, they learned, antibiotics provide a meal.
The team gathered soil from 11 sites that have varying degrees of exposure to human-made antibiotics--from a cornfield that had been fertilized with manure from cows fed antibiotics to an untouched patch of temperate forest. Every locale harbored bacteria that could survive with nothing to eat but antibiotics.
The diners hailed from 11 orders of bacteria and included relatives of pathogens such as the gut invader Shigella flexneri and the noxious Escherichia coli strain O157:H7. Compared with "conventional" antibiotic- resistant bacteria, the drug-eaters were "uberbugs." They could tolerate antibiotic concentrations 50 times higher than what qualifies a bacterium as resistant. Moreover, each of the 18 medicines the team tested--including pharmacy staples such as penicillin, ciprofloxacin, and kanamycin--could provide nourishment for at least one type of bug.
"Almost all the drugs that we consider as our mainline defense against bacterial infections are at risk from bacteria that not only resist the drugs but eat them for breakfast," says Church. He doesn't yet know how bacteria turn these supposedly lethal compounds into a meal.
The medical importance of these consumers is also unknown. In principle, the germs could cause trouble in two ways, says Wright. Microbes that are usually innocuous might pick on people, such as AIDS patients, who have crippled immune systems. Moreover, soil bacteria pass around resistance-conferring genes like teenagers swap downloaded music files, and pathogenic bacteria could likewise pick up antibiotic-digesting genes, particularly from a closely related microbe.
However, nobody has identified a pathogenic bacterium that can chow down on the drugs, Church notes. And bacteriologist Jo Handelsman of the University of Wisconsin, Madison, thinks it's unlikely that disease-causing bugs would switch to an antibiotic diet: "There are much yummier and easier things to eat in the human body."
Vol. 320. no. 5872, p. 33
DOI: 10.1126/science.320.5872.33a
Prev | Table of Contents | Next
News of the Week
MICROBIOLOGY:
Germs Take a Bite Out of Antibiotics
Mitch Leslie
As far as patients and doctors are concerned, bacteria are supposed to do one thing when they encounter antibiotics: drop dead. But a broad survey of soil microbes shows that numerous species devour even the most potent drugs. The craving for antibiotics is widespread across environments and bacterial groups, researchers report on page 100, fueling worries about the dwindling power of our main weapons against infections.
Although a few previous studies had identified antibiotic-eating strains, "nobody had done a systematic search like this," says chemical biologist Gerry Wright of McMaster University in Hamilton, Canada. "It's one of those papers that unveils a whole new area of research."
Eighty years after Alexander Fleming discovered penicillin on a moldy culture dish, the battle against killer bugs is faltering. More and more bacteria--including insidious tuberculosis strains that have cropped up (Science, 15 February, p. 894)--now shrug off almost all antibiotics. Meanwhile, few new antibiotics are reaching the clinic. Medicine is on the defensive, says microbiologist and physician Stuart Levy of Tufts University School of Medicine in Boston. "We are not keeping up with the bacteria."
Geneticist George Church of Harvard Medical School in Boston and colleagues had not planned to dig up more grim news about antibiotics. These researchers were hunting for microbes that could convert agricultural waste into biofuels and were using antibiotics in their control studies. But for some bacteria, they learned, antibiotics provide a meal.
The team gathered soil from 11 sites that have varying degrees of exposure to human-made antibiotics--from a cornfield that had been fertilized with manure from cows fed antibiotics to an untouched patch of temperate forest. Every locale harbored bacteria that could survive with nothing to eat but antibiotics.
The diners hailed from 11 orders of bacteria and included relatives of pathogens such as the gut invader Shigella flexneri and the noxious Escherichia coli strain O157:H7. Compared with "conventional" antibiotic- resistant bacteria, the drug-eaters were "uberbugs." They could tolerate antibiotic concentrations 50 times higher than what qualifies a bacterium as resistant. Moreover, each of the 18 medicines the team tested--including pharmacy staples such as penicillin, ciprofloxacin, and kanamycin--could provide nourishment for at least one type of bug.
"Almost all the drugs that we consider as our mainline defense against bacterial infections are at risk from bacteria that not only resist the drugs but eat them for breakfast," says Church. He doesn't yet know how bacteria turn these supposedly lethal compounds into a meal.
The medical importance of these consumers is also unknown. In principle, the germs could cause trouble in two ways, says Wright. Microbes that are usually innocuous might pick on people, such as AIDS patients, who have crippled immune systems. Moreover, soil bacteria pass around resistance-conferring genes like teenagers swap downloaded music files, and pathogenic bacteria could likewise pick up antibiotic-digesting genes, particularly from a closely related microbe.
However, nobody has identified a pathogenic bacterium that can chow down on the drugs, Church notes. And bacteriologist Jo Handelsman of the University of Wisconsin, Madison, thinks it's unlikely that disease-causing bugs would switch to an antibiotic diet: "There are much yummier and easier things to eat in the human body."
