FIG 4

Antibiofilm effect of antibiotic mixtures alone and in combination with bacteriophage YC#06 on biofilm formation inhibition (A, B) and mature biofilm reduction (C, D) in vitro. Antibiotic mixtures include chloramphenicol, imipenem, and cefotaxime. (A and C) Optical density at 600 nm (OD₆₀₀) was measured using the microplate reader. (B and D) Viable bacteria counting was detected using dilution plate counting method. I, bacteria added alone as control group; II, phage added as treatment group; III and IV, antibiotic mixtures added as treatment group; V and VI, antibiotic mixtures plus phage added as treatment group. For the biofilm formation inhibition experiment in panels A and B, the phage and B.m#4015, antibiotic mixtures and B.m#4015, and antibiotic mixtures plus phage and B.m#4015 were cocultured at the initial time. For the mature biofilm-reducing experiment in panels C and D, phage, antibiotic mixtures, and antibiotic mixtures plus phage were added after mature biofilm was observed. “×MIC” shows that the effective antibiotic concentrations used are at n times the MIC. MICs were chosen according to the Clinical and Laboratory Standards Institute guidelines. Data are presented as the mean ± standard deviation (SD) (*, P < 0.05).