Monday, October 31, 2005

Phages: A New Way to Fight Bad Germs

Back in June I was amazed at this story in Wired about phages, bacteria-eating viruses that could be the answer to antibiotic resistance. The first treatment to use the therapy could be available this year.

"Half a century ago, antibiotics revolutionized medicine by turning many once-deadly infections like tuberculosis into minor impediments. But overuse is rapidly rendering antibiotics ineffective, and scientists know they need a replacement fast. One of the most promising options is one that's been used in Eastern Europe and Russia for decades: bacteriophage therapy

One potential drawback is that phage therapies might be too specific for widespread use against infection, according to Carl Merril, a senior investigator at the National Institutes of Health. For example, one phage might work for one strain of Streptococcus pneumoniae (the most common type of pneumonia) but not for the 27 others.

One solution is to make a "cocktail" treatment containing several phages, but it remains to be seen how useful that approach will be.

The beauty of antibiotics was that any one antibiotic worked for many different types of infection. But it is also turning into their downfall, because they also kill good bacteria that humans need to remain healthy. Moreover, bacteria are good at finding ways to outsmart the drugs.

According to the Centers for Disease Control and Prevention, nearly 2 million people in the United States acquire an infection while in a hospital every year, and 90,000 of them die. More than 70 percent of the bacteria that cause these infections are resistant to at least one of the antibiotics commonly used to treat them.

Phage therapies are at the opposite end of the spectrum. They kill the bacteria they're meant to almost without fail, and bacteria don't become resistant nearly as often. However, Merril cautioned, "Given the narrow host range of phage, you can't use it like penicillin."

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