FIG 3.

Effect of antibiotic class on phage-antibiotic synergy. A 100-fold diluted subculture of wild-type JJ2528 was incubated for 4 h, centrifuged, washed, adjusted too an OD₆₀₀ of 1, and inoculated in a 96-well plate coated with ΦHP3 and antibiotics, and the OD₆₀₀ was measured every 15 min for a total of 24 h with shaking. Effect of different antibiotics was studied with: (A) trimethoprim; (B) colistin; (C) kanamycin; (D) ciprofloxacin; (E) ceftazidime; (F) chloramphenicol. Synograms (t = 24 h) represent the mean reduction percentage of each treatment from three biological replicates: Reduction (%) = [(OD_{growthcontrol} − OD_treatment)/OD_{growthcontrol}] × 100. The regions above the dashed lines indicate antibiotic-mediated killing with highly effective doses; the regions between the solid and dashed lines represent the interacting regions of the phage and antibiotic, and the regions below the solid lines indicate phage-mediated killing with ineffective antibiotic concentrations.