Fluent Essays

Topic - salmonella bacteria  2 pages Body; Can use a news article as a starting point, but scientific statements must be based in peer-reviewed sources.  If a news source references a study, does the news source portray the results accurately?  Are the conclusions of the researchers warranted? How does the study fit into a larger body of literature? Avoid editorializing Instructions; Font-Times New Roman, size-12, margin-1 Cover page and references will not be counted towards page limit.  Cover page should include Title, name and section. All work cited must be in same format.ARTICLE OPEN Exposure of Salmonella biofilms to antibiotic concentrations rapidly selects resistance with collateral tradeoffs Eleftheria Trampari1, Emma R. Holden 1, Gregory J. Wickham1, Anuradha Ravi1, Leonardo de Oliveira Martins 1, George M. Savva1 and Mark A. Webber 1,2✉ Most bacteria in nature exist in biofilms, which are inherently tolerant to antibiotics. There is currently very limited understanding of how biofilms evolve in response to sub-lethal concentrations of antimicrobials. In this study, we use a biofilm evolution model to study the effects of sub-inhibitory concentrations of three antibiotics on Salmonella Typhimurium biofilms. We show that biofilms rapidly evolve resistance to each antibiotic they are exposed to, demonstrating a strong selective pressure on biofilms from low antibiotic concentrations. While all antibiotics tested select for clinical resistance, there is no common mechanism. Adaptation to antimicrobials, however, has a marked cost for other clinically important phenotypes, including biofilm formation and virulence. Cefotaxime selects mutants with 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 Microbiomes (2021) 7:3 ; https://doi.org/10.1038/s41522-020-00178-0 INTRODUCTION Antimicrobial resistance (AMR) is a complex problem and a major threat to human and animal health1. Understanding how bacteria develop resistance to antibiotics is important to inform how antibiotics should be used to minimise the selection of AMR. Much of our understanding of the mechanisms of antibiotic action and resistance comes from experiments in which bacteria have been grown in liquid culture before being exposed to antibiotics. Yet, most bacteria in nature exist in biofilms, aggregated communities of cells encased in a matrix2. Biofilms represent a fundamentally different mode of life to planktonic cultures and studies have demonstrated extreme changes in gene and protein expression profiles from the same strains when grown in liquid or as a biofilm3. Many infections include a biofilm component that makes the infection difficult to treat; common examples include infections on prosthetic or indwelling devices. Biofilms are typically more tolerant to antibiotics, compared to the corresponding strain in liquid culture. One theory explaining the resistance to antibiotics of biofilms is that cells within a biofilm are metabolically inactive, and a high proportion are dormant ‘persister’ cells. In these dormant subpopulations, characterised by arrested macromolecular synth- eses, the cellular targets that the