How bacteria are not only resisting antibiotics, but eating them too
As if it's not bad enough that bacteria are increasingly becoming resistant to our best antibiotics – some bugs are even eating the drugs. An international team of scientists has now examined just how the bacteria disarm and consume the antibiotics as food, uncovering new potential ways to fight back against resistance.
Bacteria are evolving resistance to antibiotics at an alarming rate, thanks to overprescription and overuse. If left unchecked, reports suggest that by 2050 the so-called superbugs could be responsible for up to 10 million deaths a year, ushering in a new dark age of medicine where our drugs simply don't work.
Adding insult to injury, some species of bacteria flaunt their resistance by actually chowing down on antibiotics. New research out of the Washington University School of Medicine in St. Louis has set out to examine just how the bacteria manage to do this.
"Ten years ago we stumbled onto the fact that bacteria can eat antibiotics, and everyone was shocked by it," says Gautam Dantas, senior author of the study. "But now it's beginning to make sense. It's just carbon, and wherever there's carbon, somebody will figure out how to eat it. Now that we understand how these bacteria do it, we can start thinking of ways to use this ability to get rid of antibiotics where they are causing harm."
But the war isn't just being fought inside our bodies: It's in the water and soil too, thanks to waste from farms and pharmaceutical factories. The new study focused on the bacteria that live in these environments, which rapidly become resistant thanks to constant exposure to the drugs and their natural ability to easily share genetic material.
The team closely studied four species of soil bacteria that thrive by eating nothing but penicillin. First, the bugs use an enzyme known as ß-lactamase to deactivate the toxin, which is a common strategy used by antibiotic-resistant bacteria. Then they use special enzymes, which were only just discovered in this study, to break down the drug into pieces that it can eat.
The researchers also observed the genes at play during this process. In particular, three different sets of genes became active while the bacteria dined on the penicillin, but remained silent when the bug was eating sugar instead.
Armed with this knowledge, the tide could be turned against superbugs. The researchers say that it might be possible to engineer E. coli that eats penicillin, and use them to clean up these environmental antibiotic spills. That in turn could help slow down how fast bacteria in general are evolving resistance.
But before a bacterial clean-up crew becomes a viable option, the researchers say that the process needs to be sped up. Currently it takes too long for bacteria to break down antibiotics, so they wouldn't make a dent in drugs found in industrial and agricultural waste.
"You couldn't just douse a field with these soil bacteria today and expect them to clean everything up," says Dantas. "But now we know how they do it. It is much easier to improve on something that you already have than to try to design a system from scratch."
The research was published in the journal Nature Chemical Biology.
Source: Washington University