Now researchers from the University of North Carolina at Chapel Hill and the University of San Diego, La Jolla, reveal that the way we often think about antibiotics - as straightforward killing machines - needs to be revised.
The research not only adds a new dimension to how we treat infections, but also might change our understanding of why bacteria produce antibiotics in the first place.
“For a long time we’ve thought that bacteria make antibiotics for the same reasons that we love them - because they kill other bacteria,” said Elizabeth Shank, an assistant professor of biology in the UNC-Chapel Hill. “However, we’ve also known that antibiotics can sometimes have pesky side-effects, like stimulating biofilm formation.”
Shank and her team show that this side-effect - the production of biofilms - is not a side-effect after all, suggesting that bacteria may have evolved to produce antibiotics in order to produce biofilms and not only for their killing abilities.
Biofilms are communities of bacteria that form on surfaces, a phenomenon dentists usually refer to as plaque. Biofilms are everywhere. In many cases, biofilms can be beneficial, such as when they protect plant roots from pathogens. But they can also harm, for instance when they form on medical catheters or feeding tubes in patients, causing disease.
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“It was never that surprising that many bacteria form biofilms in response to antibiotics: it helps them survive an attack. But it’s always been thought that this was a general stress response, a kind of non-specific side-effect of antibiotics. Our findings indicate that this isn’t true. We’ve discovered an antibiotic that very specifically activates biofilm formation, and does so in a way that has nothing to do with its ability to kill.”
They believe that the research has generated further discussion about the evolution of antibiotic activity, and the fact that some antibiotics being used therapeutically may induce biofilm formation in a strong and specific way, which has broad implications for human health.
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“Thiopeptide antibiotics stimulate biofilm formation in Bacillus subtilis,” Rachel Bleich, Jeramie D. Watrous, Pieter C. Dorrestein, Albert A. Bowers, Elizabeth A. Shank, Proceedings of the National Academy of Sciences February 23, 2015 112 (10) 3086-3091; 2015,doi:10.1073/pnas.1414272112