Reduction in kelp forests altered sea otter and sea urchin behavior, restructuring mechanisms of ecosystem control.
Image credit: Michael Langhans (photographer).
Edited by Jennifer A. Doudna, University of California, Berkeley, CA, and approved April 28, 2015 (received for review January 25, 2015)
Significance
Antibiotic resistance of pathogens is a growing concern to human health, reviving interest in phage therapy. This therapy uses phages (natural bacterial enemies) to kill pathogens. However, it encounters many obstacles such as delivery barriers into the tissues and bacterial resistance to phages. Here, we use phages for delivering a programmable DNA nuclease, clustered regularly interspaced short palindromic repeats (CRISPR)–CRISPR-associated (Cas), to reverse antibiotic resistance and eliminate the transfer of resistance between strains. This approach combines CRISPR-Cas delivery with lytic phage selection of antibiotic-sensitized bacteria. The strategy may reduce the prevalence of antibiotic-resistant bacteria in treated surfaces and on skin of medical personnel, as it uses phages in a unique way that overcomes many of the hurdles encountered by phage therapy.
Abstract
The increasing threat of pathogen resistance to antibiotics requires the development of novel antimicrobial strategies. Here we present a proof of concept for a genetic strategy that aims to sensitize bacteria to antibiotics and selectively kill antibiotic-resistant bacteria. We use temperate phages to deliver a functional clustered regularly interspaced short palindromic repeats (CRISPR)–CRISPR-associated (Cas) system into the genome of antibiotic-resistant bacteria. The delivered CRISPR-Cas system destroys both antibiotic resistance-conferring plasmids and genetically modified lytic phages. This linkage between antibiotic sensitization and protection from lytic phages is a key feature of the strategy. It allows programming of lytic phages to kill only antibiotic-resistant bacteria while protecting antibiotic-sensitized bacteria. Phages designed according to this strategy may be used on hospital surfaces and hand sanitizers to facilitate replacement of antibiotic-resistant pathogens with sensitive ones.
Footnotes
↵1I.Y. and M.M. contributed equally to this work.
- ↵2To whom correspondence should be addressed. Email: ehudq{at}post.tau.ac.il.
Author contributions: I.Y., M.M., and U.Q. designed research; I.Y. and M.M. performed research; I.Y., M.M., and U.Q. analyzed data; R.K. contributed new reagents/analytic tools; and U.Q. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1500107112/-/DCSupplemental.
Sensitizing antibiotic-resistance bacteria
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