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12 December 2013 1:00 pm ,
Vol. 342 ,
The iconic 125-year-old Lick Observatory on Mount Hamilton near San Jose, California, is facing the threat of closure...
Recent results from the Curiosity Mars rover have helped scientists formulate a plan for the next phase of its mission...
A new, remarkably powerful drug that cripples the hepatitis C virus (HCV) came to market last week, but it sells for $...
In pretoothbrush populations, gumlines would often be marred by a thick, visible crust of calcium phosphate, food...
Evolutionary biologists have long studied how the Mexican tetra, a drab fish that lives in rivers and creeks but has...
Victorian astronomers spent countless hours laboriously charting the positions of stars in the sky. Such sky mapping,...
In an ambitious project to study 1000 years of sickness and health, researchers are excavating the graveyard of the now...
Stefan Behnisch has won awards for designing science labs and other buildings that are smart, sustainable, and...
- 12 December 2013 1:00 pm , Vol. 342 , #6164
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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.''