Mice were anesthetized with inhalation of isoflurane and instilled with PAO1 bacteria (sensitive to all peptides), through intra-tracheal inoculation of ~3 × 106 CFU per mouse in 50 µl PBS. Two hours after the bacterial infection, the peptide was intra-tracheally administered at desired dosage in 50 µl of PBS. Control mice were instilled with 50 µl of PBS without peptide. For repeated dosage experiments, the peptide was intra-tracheally instilled at 2 hours and 12 hours after bacterial infection.