New Antibiotic Approach Harnesses Cas9 Enzyme to Specifically Attack Drug-Resistant Microbes

The multitude of microbes scientists have found populating the human body have good, bad, and mostly mysterious implications for our health. But when something goes wrong, we defend ourselves with the undiscriminating brute force of traditional antibiotics, which wipe out everything at once, regardless of the consequences. Researchers at Rockefeller University and their collaborators are working on a smarter antibiotic. And in research published online on October 5, 2014 in Nature Biotechnology, the team describes a “programmable” antibiotic technique that selectively targets the bad microbes, particularly those harboring antibiotic-resistance genes, while leaving other, more innocent microbes alone. "In experiments, we succeeded in instructing a bacterial enzyme, known as Cas9, to target a particular DNA sequence and cut it up," says lead researcher Dr. Luciano Marraffini, head of the Rockefeller’s Laboratory of Bacteriology. "This selective approach leaves the healthy microbial community intact, and our experiments suggest that by doing so you can keep resistance in check and so prevent certain types of secondary infections, eliminating two serious hazards associated with treatment by classical antibiotics." The new approach could, for instance, reduce the risk of C. diff, a severe infection of the colon, caused by the Clostridium difficile bacterium that is associated with prolonged courses of harsh antibiotics and is a growing public health concern. The Cas9 enzyme is part of a defense system that bacteria use to protect themselves against viruses. The team coopted this bacterial version of an immune system, known as a CRISPR (clustered regularly interspaced short palindromic repeats) system and turned it against some of the microbes.
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