Life Science Blog

Trojan Horse Metal Kills Monster Infections

December 2, 2008

Biofilms. They’re like Frankenstein’s monster in microscopic form. They are living, heaving, powerful patchworks of microscopic creatures that have learned to seize the advantage of numbers. When individual, free-wheeling microbes latch onto surfaces – say, your shower drain, your teeth or your catheter – then others of the same species join them and they grow both by inviting their friends and by old-fashioned reproduction. They coalesce into something that is greater than the sum of  its parts. If the little critters that make them up are infectious bacteria, individually they may be easy enough for the body’s immune system to tackle on its own. But when the bacteria come together into a biofilm, they are a menace to health, sometimes a threat to life and are very tough to kill, even with antibiotics.

Some exciting work has revealed ways that the bacteria might communicate with each other. In the future, we may be able to crack their codes, confuse them and  disband the whole community.

But for now, one group of scientists is using an old trick: the Trojan Horse. Peter Greenberg, microbiologist at the University of Washington, led a team of investigators that performed a chemical sleight of hand to bacteria of the species Pseudomonas aeruginosa, when they had formed a biofilm. The researchers tricked the infectious bacteria into absorbing gallium, a metal that looks like iron, something they need for their metabolisms. The nasty surprise was that it looked like the thing the bacteria needed, but it didn’t work the same way. Kind of like filling your gas tank with Jim Beam.

“It’s an agent that kills Pseudomonas aeronginosa when it’s in a biofilm” Green said. “It thinks it’s iron, so it delivers it to its cells and dies.”

In fact, when the gallium was used in combination with a common antibiotic, the biofilms were brought to their knees so efficiently that the scientists wrote of the effect with the glee of teenagers slaughtering aliens in Halo 3: the combination “caused massive killing of… cells in mature biofilms.”

Massive killing. This could be formidable, better still if it could be adapted to wipe out infections by other kinds of microbes as well.

Also on Scienceline:

Deciphering Bacteria’s Defenses, One Gene at a Time

Is there a cavity vaccine? Fighting plaque-forming biofilms

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