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Wednesday, February 22, 2006
Soil grows drug-resistant bacteria
By Zosimo T. Literatus, R.M.T.
Breakthroughs
The demands of survival make even the lowest of organisms develop an elaborate defense system that its foes could not easily destroy.
Against human antibiotics or fellow bacterial toxins, soil bacteria have been recently found with astonishing armory of weapons to protect themselves.
A team of microbiologists, led by Gerard Wright McMaster, University in Ontario, Canada, identified some ways in which soil bacteria neutralize antibiotics, an information that could help anticipate the next wave of drug-resistant bacteria to plague humans.
In a recent study, the team collected handfuls of dirt from towns and forests across Canada, and grew the bacteria found in them. They isolated 480 different strains of the common soil bacteria, Streptomyces, alone. Genus Streptomyces are known to synthesize a large number of antibiotics. The team threw in 21 different antibiotics (some natural, some synthetic) at the bacterial growths to see if they would survive.
Each of the Streptomyces strain showed no effect from seven to eight antibiotics, on average. Two especially resistant strains were not vulnerable to 15 drugs. The microorganisms turned out to be capable of finding ways to detoxify some drugs, like adding a sugar molecule on to the drug Telithromycin, which prevents it from crippling the bacterial cell. This ability to fashion an effective defense against antibiotics enabled them to survive against an array of toxic chemical released on them by other bacteria, fungi, and plants in the underground.
“The chances that these genes will end up in a disease-causing organism at some future point are high,” says microbiologist Abigail Salyers, who studies microbe gene transfer at the University of Illinois at Urbana-Champaign.
Researchers believe that these genes allowed certain bacteria to resist Vancomycin, one of the last lines of antibiotic prescribed by doctors.
Vancomycin is originally obtained from soil-dwelling bacteria, too.
This new discovery is both a danger and an opportunity. It is a dangerous discovery because this drug-resistance could be developed in certain bacteria, such as Staphylococcus areus, an infection obtained in hospitals, and is already resistant to almost everything on the pharmacy shelf.
It is also an opportunity because it provides us the tool to formulate new antibiotics against soil bacteria that can be used against other drug-resistant bacteria.
In his poem, The Secret of the Sea, poet Henry Wadsworth Longfellow wrote: “Wouldst thou”—so the helmsman answered—”Learn the secret of the sea?/Only those who brave its dangers/Comprehend its mystery!” (For comments and suggestions, email to ztliteratus6046@lycos.com)
For Bisaya stories from Cebu. Click here. (February 22, 2006 issue)
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