A Better Germ-Killer?

A special coating that could be applied to toys, telephones, keyboards, doorknobs and even surgical equipment kills most of the common bacteria that cause serious infection, researchers say.

Joerg Tiller of Massachusetts Institute of Technology said the polymer could guard against infections commonly spread by sneezes and dirty hands.

"You could coat any type of surface with this material, and it would be there permanently," said Tiller. "It is chemically attached so that it cannot be washed away."

In a study appearing Tuesday in the Proceedings of the National Academy of Sciences, Tiller and his co-authors said laboratory tests show that the coating, called hexyl-PVP, was able to kill up to 99 percent of Staphylococcus, Pseudomonas and E. coli, all common disease-causing organisms.

Tiller said the coating, applied to glass slides, was tested by spraying the slides with a concentrated solution of the bacteria groups common in household and hospital infections. The results were compared to uncoated glass slides that also were exposed to the bacteria solution.

"The test solution was rather like what happens when you sneeze or cough," spraying surfaces with germs, said Tiller.

On the glass slides treated with hexyl-PVP, 94 percent to 99 percent of the Staphylococcus organisms were killed. For Pseudomonas and E. coli, the kill rate was consistently at 99 percent.

Tiller said the polymer kills bacteria by a powerful chemical-electrical action.

"It is a polymer with permanent positive charge," said Tiller. "This positive charge destroys the bacteria cell walls and membranes."

Tiller said the kill mechanism probably would not allow bacteria to develop a resistance, as can happen with antibiotics, he said.

"It is a chemical kill," he said. "For them to develop resistance, the bacteria would have to change their whole composition, and I don't think this can be done."

Most of the nation's antibiotic resistance experts were attending Monday's general meeting of the American Society for Microbiology in Orlando, Fla., and could not be reached for comment.

To test the polymer for toxicity, Tiller said the researchers put mouse cells on a coated surface.

"The mouse cells grew, but this is only the first test," he said. "As long as the polymer remains attached to a surface, it should not be toxic" to humans.

The anti-bacterial coating, said Tiller, could be incorporated into the manufacturing process so that the surface of many products could be permanently sterile.

He said the surfaces would require periodic washing to remove dead bacteria that float out of the air and land on the killing surface.

Tiller and his co-authors hold a patent on the chemical coating but are not involved in any effort to bring the germ-killing technology to the market, he said.

By Paul Recer
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