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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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7 November 1996 8:00 pm
The notorious "flesh-eating" bacterium appears to sweet-talk its way deep into vulnerable tissues. A report in the 7 November issue of the Journal of Clinical Investigation suggests that a coating of complex sugars may help vicious strains of streptococcal bacteria cause life-threatening infections. The finding may lead to a test someday that would help doctors identify strains likely to cause the severe infections.
Streptococcus can cause mild infections--witness strep throat--or horrifyingly invasive infections that turn tissue into soup. Researchers have long suspected that a coating made of a complex carbohydrate called hyaluronic acid influences the severity of strep infections. Michael Wessels and his colleagues at Harvard University and Brigham and Women's Hospital in Boston found that it does--but in an unexpected way.
They found that, as predicted, a strep strain genetically engineered not to manufacture the hyaluronic acid capsule failed to cause invasive infections in mice, while the encapsulated bacterium did. But when they exposed cultured human skin cells to the bacteria, they found that only the naked bacterium penetrated the cells. And that's what defeated the sugar-free bugs: The skin cells quickly killed the invaders. The sugar-coated bacterium, meanwhile, did not enter the skin cells and therefore escaped, which could explain how invasive strep slips into deeper tissues.
The finding is a step toward a better understanding of the molecular interactions between Streptococcus and its hosts, says James Musser, a molecular pathobiologist at Baylor College of Medicine in Houston. Indeed, it seems to dovetail with Musser's own work; he studies a strep toxin that appears to do its damage in tissues outside individual cells. The toxin sets off a chemical reaction that melts the protein bonds between cells and ``essentially causes the host tissue to eat itself,'' Musser says.
Both scientists say potential treatments that target the sugar coating are a long way off. But ``this does give us a better insight into how these organisms produce disease,'' says Wessels. ``And that's always the first step in figuring out something to do about it.''