Figure 1.

The polymer pEt_20 reverses antibiotic resistance phenotype in MDR Gram‐negative A. baumannii (BAA‐1789). a) Schematic presentation of the unique antimicrobial mechanism of the polymer–membrane penetration followed by binding of cytosolic proteins and genes, which might be a reason for reversing antibiotic resistance phenotype and enhancing antimicrobial activity. b) MICs and MBCs of antibiotics with and without pEt_20. MICs of antibiotics were interpreted according to the Performance Standards for Antimicrobial Susceptibility Testing of Clinical and Laboratory Standards Institute (CLSI), 2105. R: resistant; I: intermediate; S: susceptible. c) MIC fold reduction. d) MBC fold reduction of antibiotics in the presence of pEt_20. The concentration of pEt_20: 7.8 µg mL⁻¹ (0.5× MIC), at which it did not kill bacteria (≈0% killing efficiency as compared to CFU at 0 h). The polymer pEt_20 reduced antibiotic MIC to the susceptible level or even lower, and enhanced bactericidal effect of the antibiotics as evidenced by decreased MBC values. Limit of detection: 50 CFU mL⁻¹. MIC and MBC data are representatives of three biological replicates.