Toxic gas helps bacteria resist antibiotics
Last Updated: Friday, September 11, 2009 | 2:05 PM ET
CBC News
MRSA, seen here in an electron micrograph, uses nitric oxide to resist antibiotics, researchers say. (Canadian Press)Some deadly superbugs produce enzymes that help them to resist a wide range of antibiotics, scientists have found.
The discovery could offer a way to boost existing medications in fighting infections like methicillin-resistant Staphylococcus aureus, known as MRSA, and anthrax.
In Friday's issue of the journal Science, U.S. researchers say some bacteria produce enzymes for nitric oxide that help the microbes to resist antibiotics. If drugs could be created to inhibit this defence mechanism, it could increase the potency of current pharmaceuticals.
"Developing new medications to fight antibiotic-resistant bacteria like MRSA is a huge hurdle, associated with great cost and countless safety issues," said study author Evgeny Nudler of New York University's medical centre.
"Here, we have a short cut where we don't have to invent new antibiotics. Instead, we can enhance the activity of well established ones, making them more effective at lower doses," he added in a statement.
Nitric oxide, or NO, is a simple molecule. But it wasn't until the late 1980s that researchers discovered that the toxic gas and air pollutant also plays an important role in learning and memory, control of blood pressure, penile erection, digestion, fighting infection and cancer in mammals.
"We show that NO generated by [bacteria] increases the resistance of bacteria to a broad spectrum of antibiotics, enabling the bacteria to survive and share habitats with antibiotic-producing microorganisms," the researchers write.
The team found that many antibiotics work against bacteria through the production of reactive oxygen, also known as oxidative stress, which damages the microbes' DNA.
Nitric oxide seems to protect bacteria from the oxidative stress, countering the effect of antibiotics, the researchers said. The compound also helped to modify the toxic effects of antibiotic compounds.
The study focused on Gram-positive bacteria such as MRSA and anthrax, which make NO from the common amino acid arginine, the team said.
The study was funded by the U.S. National Institutes of Health.
