Antibiotics are used to combat the ever-present threat of infectious diseases, but bacteria are continually evolving an assortment of defenses that allow for survival against even the most potent treatments. Biofilm is a collection of microorganisms that live within an extracellular polymeric substance (EPS) matrix adhered to other surfaces. The EPS serves as a protective barrier between a group of microorganisms and their environment, providing a mechanism for the bacteria to withstand increasing concentrations of antibiotics. Using PHL628 <i>E. coli</i>, which readily form robust biofilms in the laboratory, we exogenously overexpressed two transcription factors, RpoH and RpoF, and measured their influence on bacterial survival and biofilm formation during antibiotic treatment. We hypothesized that activation of these pathways, which upregulate genes that respond to thermal stress and nutrient deprivation, respectively, could sensitize bacteria to antibiotic treatment. We considered several classes of antibiotics, including macrolides, glycopeptides, and quinolones. We measured minimum inhibitory concentration of the antibiotic and its impact on biofilm formation using UV-visible spectroscopy. For cells treated with erythromycin and vancomycin, preliminary results suggest that RpoH overexpression promotes an increased antibiotic tolerance at 28 °C. These experiments will elucidate the relationship between RpoH and RpoF signaling pathways and antibiotic mechanisms, and could be further explored for the development of adjuvants for existing antibiotics.

Influence of RpoH and RpoF overexpression on quinolone, macrolide, and glycopeptide antibiotic tolerance and biofilm growth in <i>E. coli</i>

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Influence of RpoH and RpoF overexpression on quinolone, macrolide, and glycopeptide antibiotic tolerance and biofilm growth in E. coli