Breakthrough May End Need of Antibiotics For Superbugs
By Maggie Fox
Health and Science Correspondent
WASHINGTON (Reuters) - A new approach to fighting toxic bacteria could mean an end to the problem of drug-resistant ''superbugs,'' California researchers said Thursday. They found a single protein that controls production of all the poisons that make staphylococcus bacteria dangerous and also found two ways to stop the protein's action.
Naomi Balaban and colleagues at the University of California, Davis, said they hoped their new approach, which uses either a vaccine or a protein molecule, would provide an alternative to antibiotics.
``It's all by peaceful terms for the bacteria, so maybe it won't resist it as much,'' Balaban, an infectious-disease specialist, said in a telephone interview. Staphylococcus aureus -- staph for short -- is the most common cause of infection in the United States. It causes infections ranging from harmless pimples to toxic shock syndrome.
Staph is usually easy to treat with antibiotics, but drug-resistant forms have evolved. Most frightening is a strain that resists vancomycin, the powerful antibiotic seen as the last line of defense against bacteria. Only three cases have been reported, but experts predict there will be more.
Balaban said her approach avoided the whole problem. Writing in the journal Science, she said she found a way to stop the staph bacteria from producing the toxins that make it dangerous. ``Unlike antibiotics, it does not kill the bacteria, so there is no pressure on the bacteria to mutate,'' she said. There is no real need to kill the bacteria, she said. ``The bacteria doesn't necessarily cause disease because it enters the body but because of the toxins it produces,'' she said. She believes the toxins are meant to enhance the bacteria's survival.
Fighting each separate toxin would be unwieldy and time-consuming. So Balaban looked for a protein that controls all toxin production, and she found it. ``There is one protein that activates the cascade of events and activates many toxins, so all you have to deal with is the one protein,'' she said.
Balaban named the protein RAP, for RNAIII activating protein. Using mice, she found a way to generate antibodies to the protein. Antibodies are the molecules that the body's immune system uses to flag invaders for killer cells to destroy. A second protein, called RAP-inhibiting peptide, is produced by staph bacteria when they are not in a disease-causing stage and can block RAP's effects.
``So antibodies to this protein, which I call RAP, block it, and a peptide that I call RIP competes with RAP,'' she said. Injected into mice, the RAP antibody prevented cellulitis, a skin infection, more than 70 percent of the time, she said. In mice that did develop infection, the lesions were smaller than in those that did not get the RAP antibodies. Mice who got injections of staph along with the second protein, RIP, were much less likely to develop infections. Balaban said RIP could be developed as a coating to put on catheters, a notorious cause of staph infections, or tampons, which can cause toxic shock syndrome. Milk pumping machines represent another possible application, as staph infections from the milkers cause a common udder infection known as mastitis. Besides preventing the evolution of drug-resistant staph, there is a second advantage to the new approach, Balaban said. Antibiotics can kill off the useful bacteria in the body, such as those that help digestion. The result can be yeast infections. Treating an infection without killing bacteria would maintain the healthy balance of micro-organisms in the body. Balaban said she was testing her idea further but thought it could be applied to other bacteria that cause infections, such as streptococci and enterococci.

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