Effects of aztreonam lysine (AzLys) on P. aeruginosa phage phiKZ that uses the T4P as its receptor. (A) Box plot of plaque diameter, and (B) bar chart of average phage titer, of phage phiKZ in the presence of different concentrations of sub-inhibitory AzLys determined by a modified double agar overlay assay. Results are from three separate trials, with error bars representing the (A) largest and smallest plaque diameter and (B) standard deviation. Statistical analysis was performed using a one-way ANOVA with Dunnett’s post-test compared to the control (** p < 0.01; *** p < 0.001; ns, not significant). (C) Infection efficiency of phiKZ in the absence (-) or (+) presence of 1.06 μg/mL AzLys. Images are representative of three biological replicates, each with three technical replicates. (D) Killing effect of phage phiKZ was examined with or without the addition of 1.06 μg/mL AzLys. Values are averages from three trials, with error bars representing the standard error of the mean (SEM). Statistical analysis was performed using unpaired t-tests (** p < 0.01, **** p < 0.0001; ns, not significant).