Allison Lopatkin, a doctoral student in Dr. Lingchong You’s laboratory, is the lead author of a new study published online in Nature Microbiology that turns assumptions about the cause of antibiotics resistance on its head and suggests new directions for antibiotic use.
Researchers previously concluded that antibiotics increased the amount of genetic swapping taking place, contributing to antibiotic resistance. (Bacteria can swap DNA through a process called conjugation, which allows helpful genes to spread quickly between individuals and between species). But Lopatkin, You, and others on the research team designed an experiment to consider an alternate cause: that antibiotics kill off non-resistant strains and allow new resistant strains to thrive instead.
They tested nine clinical pathogens commonly associated with the rapid spread of resistance and exposed them to ten common drugs representing each major class of antibiotics. The rates of genetic swapping in each test remained flat and, in a few cases, actually decreased slightly as the concentration of antibiotics grew. They observed that antibiotics did not increase gene swapping but let the newly resistant bacteria emerge as the winners. As Allison Lopatkin describes it, “we showed at the single-cell level that the exchange of resistant genes is not influenced by antibiotics at all, which is in contrast to the literature.”
The You lab, including Shuqiang Huang, Jaydeep Srimani and Tatyana Sysoeva, and their collaborators at Nova Southeastern University, the University of Maryland; and the Johns Hopkins University Applied Physics Laboratory, hope their research will contribute to the design of better antibacterial protocols. They expect their follow up research to contribute to the design of antibiotic treatment protocols that will be effective but won’t promote the spread of antibiotic resistance.
The work is supported by grants from US Army Research Office, the National Institutes of Health and the Packard Foundation.
Find the article here.
“Antibiotics as a selective driver for conjugation dynamics,” Allison J. Lopatkin, Shuqiang Huang, Robert P. Smith, Jaydeep K. Srimani, Tatyana A. Sysoeva, Sharon Bewick, David Karig, Lingchong You. Nature Microbiology, April 11, 2016. DOI: 10.1038/NMICROBIOL.2016.44