- 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.