Figure 3: The effect of pyridoxine derivatives on the thickness of preformed biofilms of (a) S. aureus and (b) S. epidermidis. Three-day-old biofilms were washed twice by sterile broth, exposed for 24 h to antimicrobials at concentrations as indicated and then stained by crystal violet. Wells incubated with pure medium served as a control (indicated as E). Standard deviations in each case did not exceed 15% and are not provided. The values for 36 significantly differ from the control value (without any antimicrobials) that were indicated with as judged by Manna-Whitney test.