Scientific Publications
Exposure of Salmonella biofilms to sub-lethal concentrations of antibiotics rapidly selects for resistance but with collateral tradeoffs
npj biofilms and microbes
Most bacteria in nature exist in biofilms, which are inherently tolerant to antibiotics. There is very currently limited understanding about how biofilms evolve in response to sub-lethal concentrations of antimicrobials. In this study, we used a biofilm evolution model to study the effects of sub-inhibitory concentrations of three antibiotics on Salmonella Typhimurium biofilms. We found that biofilms rapidly evolved resistance to each antibiotic they were exposed to, demonstrating a strong selective pressure on biofilms from low antibiotic concentrations. Whilst all antibiotics selected for clinical resistance, there was no common mechanism. Adaptation to antimicrobials, however, had a marked cost for other clinically important phenotypes including biofilm formation and virulence. Cefotaxime selected mutants which had the greatest deficit in biofilm formation followed by azithromycin and then ciprofloxacin. Understanding the impacts of exposure of biofilms to antibiotics will help understand evolutionary trajectories and may help guide how best to use antibiotics in a biofilm context. Experimental evolution in combination with whole-genome sequencing is a powerful tool for the prediction of evolution trajectories associated with antibiotic resistance in biofilms.
npj biofilms and microbes
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