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 …