View Full Version : Novel drug kills resistant bacteria

05-20-2006, 11:43 PM
A newly recognized compound can wipe out some of the most troublesome antibiotic-resistant bacteria, laboratory tests show. The drug works by sabotaging a microbe's production of fatty acids.

Scientists at Merck Research Laboratories in Rahway, N.J., discovered the compound, which they call platensimycin.

The findings are preliminary but impressive, says Eric D. Brown, a microbiologist at McMaster University in Hamilton, Ontario. "This is a really promising story in a field that has had quite a bit of disappointment," he says.

Roughly 90,000 people in the United States acquire fatal infections in hospitals every year, according to data from the Centers for Disease Control and Prevention in Atlanta. Nearly three-fourths of those deaths can be traced to antibiotic-resistant microbes.

Merck chemist Sheo B. Singh and his colleagues screened roughly 250,000 natural compounds in search of potent antibacterials. This approach makes sense, Brown says, because organisms in nature "are constantly in warfare with each other." He notes that natural compounds work well as drugs because they target specific weaknesses in rival organisms.

The search led to platensimycin, a small molecule made by the bacterium Streptomyces platensis. That bug normally lives in soil in South Africa.

In the May 18 Nature, the researchers report that platensimycin promptly kills lab-dish colonies of staphylococcus and enterococcus bacteria that resist drugs such as vancomycin and methicillin. When the researchers continuously infused mice with the drug in a first test, it killed Staphylococcus aureus that wasn't drug resistant.

Platensimycin is structurally different from other antibiotics. Unlike most of those drugs, it binds to and neutralizes an enzyme called FabF, which bacteria use to make fatty acids. Platensimycin "preexisted in nature to get this job done," Brown says. "This was pretty good detective work at Merck."

Fatty acids are essential for building and maintaining the membrane that lines the bacterial cell wall. FabF is different from the corresponding enzyme in mammals, suggesting that platensimycin won't inhibit fatty acid synthesis in people, says Charles O. Rock, a biochemist at St. Jude Children's Research Hospital in Memphis, Tenn.

more... http://www.sciencenews.org/articles/20060520/fob1.asp