Censoring (Bacterial) Speech

December 16, 2014
X-ray of human body holding up their hand to green bacteria.

In recent years, it’s been shown that when many bacteria invade our bodies, they have a way of sensing when their numbers are great enough to resist our immune system’s defenses. This “quorum sensing” works through a molecular signal; when received, it gives bacteria the go-ahead to launch an all-out infection.

Quorum sensing is used by infectious bacteria like P. aeruginosa, which causes pneumonia. Once the signal goes out that a quorum has been reached, the bacteria release virulence factors that help them attack, and become established in, lung cells. But Mikael Elias, an assistant professor of biochemistry, molecular biology and biophysics, and his colleagues have identified a substance that acts as the signal. They’ve discovered that shutting off production of the substance—a molecule called a lactone—gives rats protection from pneumonia, even when the numbers of bacteria remain high. Because this treatment doesn’t kill the bacteria, they may feel less selection pressure to develop resistance, says Elias. He adds that the technique holds promise as a preventive measure for cystic fibrosis patients, who are prone to infection by the bacteria, and in hospitals, where P. aeruginosa is an opportunistic pathogen. The research was published in the journal PLoS One.