From: Maggie Fox, Reuters
Published November 3, 2004 12:00 AM

New Methods Control Bugs Without Drugs, Say Researchers

WASHINGTON — Pitting one germ against the other, researchers said this week that they had developed at least two new methods of fighting infection without the use of antibiotics.


One method uses a deadly enzyme made by viruses called bacteriophages that precisely execute bacteria, and another uses compounds made by one bacteria to shut down another without actually killing it.


Each illustrates potential new ways to fight the growing problem of superbugs — bacteria that have mutated the ability to resist most or even all of the antibiotics used against them.


They might also work against biological agents such as anthrax, the researchers told a meeting sponsored by the American Society for Microbiology.


A single squirt of the bacteria-killing enzyme may keep an infected person from sneezing out bacteria for up to a week, said Dr. Vincent Fischetti of Rockefeller University in New York.


"These are enzymes that, basically, punch a hole in the bacteria and cause them to explode," Fischetti told a news conference.


They have used them to decontaminate animals of pesky bacteria such as Group A streptococci and staphylococci.


"We can eliminate these organisms from the noses of these animals," Fischetti said.


They tried it intravenously against the anthrax bacillus. "We could save 90 percent of the animals with a single dose of the enzyme," said Fischetti, whose work is funded by the Department of Defense's Advanced Research Projects Agency or DARPA.


They are planning tests in mice, monkeys, and perhaps rabbits and will use the results to seek permission to test the enzyme for safety in human volunteers.


New Food and Drug Administration rules allow researchers to test drugs against potential biological agents in two animal species, as there is no ethical way to test them in people.


"These enzymes work instantly," Fischetti said. They could be sprayed into the nose in a saline buffer, he said. And there is no evidence, yet, that bacteria can develop mutations that will allow them to evade these enzymes, he said.


Using Bugs to Fight Bugs


Dr. Richard Novick and colleagues at New York University's medical school looked specifically for ways to stop bacteria from attaching to and killing cells in the body.


They found peptides, short pieces of proteins, that regulate this behavior by bacteria.


"We happen to have hit on one of these that provides an Achilles heel of the organism," Novick told the news conference. "We can disarm the organism ... simply by introducing one of these inhibitory factors."


It turns out that the first three hours are critical for infecting bacteria to get a foothold, Novick said. The peptide holds the bacteria in check just long enough to give immune system cells time to get there and destroy the invaders.


The peptide, called auto-inducing peptide, affects signaling within the bacteria.


Staphylococcus aureus — one of the worst causes of infections caught in hospitals — have evolved into four different strains, each with a different version of this peptide.


"Remarkably and conveniently for us, the peptide produced by any one of the subspecies blocks activation of the virulence response by any of the others," Novick said in a statement.


They created a version of the peptide in the lab that blocks all four and are now trying to improve it so it works even more broadly and lasts longer.


Source: Reuters


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