FIG 4.

Elimination of anaerobic survivors. (A) Validation of the predicted antibiotic susceptibilities of different anaerobic persister populations was assessed by adding a second antibiotic to wells with bacteria that were previously challenged for 24 h with ceftazidime (cefta) (black bars) and ciprofloxacin (cipro) (gray bars). The survival frequencies were assessed after a further 24 h of incubation with the second antibiotic. Controls that underwent 48 h incubation with the initial antibiotic only were included for comparison. (B) Reversal of oxygen-dependent drug tolerance by introduction of oxygen was assessed by incubating 24-well plates containing bacteria that were previously challenged for 24 h with ceftazidime (black bars) and ciprofloxacin (gray bars), with aeration at 150 rpm. The survival frequencies were assessed after a further 24 h of incubation with shaking. Controls that underwent 48 h of static incubation were included for comparison. (A and B) Error bars represent the standard deviation over the mean values from at least three independent experiments.