Sub-Inhibitory Treatment of Gentamicin in Escherichia coli Decreases T7 Bacteriophage Infectivity and Cell Lysis

Increasing rates of multidrug resistant Escherichia coli infections have become a growing concern worldwide. With our current repertoire of antibiotics becoming less effective against bacterial infections, novel antimicrobial therapies are needed. Bacteriophages have been proposed as an alternative therapy against antibiotic resistant bacteria. Previous literature has proposed that E. coli release outer membrane vesicles that can prevent bacteriophage infection. The presence of gentamicin has been shown to increase the production of outer membrane vesicles (OMVs). To determine if treating E. coli UB1005 with gentamicin decreases infectivity of T7 bacteriophage, we treated E. coli UB1005 with a sub-inhibitory concentration of gentamicin and measured T7 infectivity and the rate of cell lysis. We hypothesized that treating E. coli UB1005 with a sub-inhibitory concentration of gentamicin would result in reduced bacteriophage infectivity and cell lysis. We observed decreased T7 infectivity using both a plaque forming assay and a bacterial growth curve to observe cell lysis, a methodology developed in this study. Additionally, bacterial growth curve results indicate a greater decrease in T7 cell infectivity when E. coli is in exponential phase compared to stationary phase.