FIG 2.

Bacterial damage of P. aeruginosa ceftazidime-resistant (CAZ-r) (A) and ceftazidime-susceptible (CAZ-s) (B) isolates induced by the coincubation with PMNs and CAZ for 24 h. Bacterial damage of planktonic cells (PL) and biofilms (BF) was assessed by XTT assay. Data are presented as means ± SE of the percentage of damage of planktonic cells or biofilms from all experiments with each of the six clinical isolates. Asterisks demonstrate significant differences between planktonic cells and biofilms for the indicated concentrations of PMNs alone, drug alone or their combination: *, P < 0.05; **, P < 0.01. The lowercase letters show significant differences for the indicated combination of PMNs with CAZ: a, additivity; n, antagonism.