Figure 4

Intracellular killing assay of antibiotics. A549 cells (1 × 10⁵ cells/well) were infected for 1 h at 37°C with 1 × 10⁷ CFU of YS001 (A) or YS005 (B) in the absence of antibiotics. After a 1-h infection followed by a 1-h incubation period with GEN (100 μg/ml), the cell culture was incubated in the presence or absence (control) of AMP, AZM, CLR, CFPN, or LVX (1 μg/ml). Two hours later, the surviving intracellular bacteria were enumerated by plating. Data represent the means ± SD of three experiments with triplicate assays. *, P < 0.05 (compared with control). **, P < 0.01 (compared with control). ND, not detected.