Tuesday, February 21, 2006


Discovery Could Disarm Flesh-Eating Bacteria

Inactivating an enzyme renders bug vulnerable to immune system, experts say

HealthDayBy Robert PreidtMonday, February 20, 2006

MONDAY, Feb. 20 (HealthDay News) -- Scientists say they've discovered a secret weapon wielded by the family of Streptococci bacteria that causes strep throat, toxic shock and, in rare cases, the "flesh-eating bacteria."

These "group A" Streptococcus bacteria use a specific enzyme to escape defensive nets set up by the body's immune system, researchers at the University of California, San Diego (UCSD) report.

The discovery could lead to new treatments for serious infections, the scientists say.
"These findings suggest a novel approach to treating serious Strep infections, such as flesh-eating disease, by assisting our body's own defense system," senior author Dr. Victor Nizet, associate professor of pediatrics at UCSD and an infectious diseases physician at Children's Hospital in San Diego, said in a prepared statement.

He and his colleagues studied the interaction between Strep bacteria and neutrophils, specialized white blood cells that play an important role in protecting the body against pathogenic microbes. Previous research found that neutrophils release "nets" composed of DNA and toxic compounds. These nets entrap and kill bacteria that have invaded the body.

But this study found that Strep bacteria release an enzyme that degrades these nets. This enables the Strep bacteria to escape the net and spread throughout the body. However, disabling the gene that creates this enzyme makes Strep bacteria vulnerable again to the nets.

"Deprived of this single enzyme, the mutant Strep strain was easily killed by human neutrophils. In addition, the mutant Strep bacteria no longer produced a spreading infection when injected into the skin of experimental mice," lead author John Buchanan, research scientist in the UCSD department of pediatrics, said in a prepared statement.

The findings appear in the Feb. 21 issue of the journal Current Biology.


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