MIC.

The MIC was determined by the broth microdilution method according to CLSI guidelines. Muller-Hinton broth (MHB) was supplemented with 0.1% Tween 80 to prevent the absorption of compounds to plastic surfaces. Cell concentration was adjusted to about 5 × 10⁵ CFU/ml, and cells were incubated for 20 h at 37°C. The MIC was defined as the lowest concentration of antimicrobial agents that resulted in no visible growth. The MICs of teixobactin and vancomycin in the presence of purified cell wall components were measured with the method described above. Purified peptidoglycan suspension was added to MHB to an optical density at 600 nm (OD₆₀₀) of 0.1. The medium containing antibiotics and peptidoglycan was preincubated at 37°C for 1 h before adding bacterial cells.