A Watson–Marlow 205S peristaltic pump was used to maintain the AB medium flow with or without 0.5% ginseng at a constant rate of 3 mL h−1. Biofilm tolerance to tobramycin was LDK378 mouse assessed by supplementing the medium to the 3-day-old P. aeruginosa PAO1 and PDO300 biofilms with

tobramycin at concentrations of 20 μg mL−1. The tobramycin treatments were continued for 24 h. Bacterial viability was assessed by staining ginseng-treated biofilms with 20 μM of propidium iodide for 10 min, followed by confocal laser scanning microscope (CLSM) observation. The biofilms of P. aeruginosa PAO1, PDO300 and NH57388A were cultivated in flow chambers for 7 days. The tolerance of biofilms to ginseng was assessed by adding 0.5% ginseng to the influent medium of 7-day-old preformed biofilms for 24 h. Images were recorded from hour 0 to hour 24 under CLSM. Bacterial viability in biofilms was assessed using propidium iodide staining as described above. All microscopic observations were performed on a Zeiss LSM510 confocal laser scanning microscope, CLSM (Carl Zeiss, Jena, Germany), equipped with an argon laser detector and filter sets for monitoring of green fluorescent

protein (GFP) fluorescence. Images were obtained using a 40 ×/1.3 Plan-Neofluar Oil objective. Vertical cross-section images were generated using the imaris FK506 software package (Bitplane AG, Zurich, Switzerland). 1 Swimming. Bacteria were inoculated using a sterile toothpick at the center of 5 mm ABT plates (AB medium containing 2.5 mg L−1 thiamine, 0.3% Bacto agar, 0.2% Casamino acids and 30 mM glucose). The swimming zone was measured after a 48-h incubation at room temperature. Forty 12-week-old healthy female Balb/c mice were used in the study. The animals were divided into four groups and each contained 10 mice. Pseudomonas aeruginosa PAO1 and PAO1-filM were used as challenge strains, which were immobilized in alginate beads as described previously (Wu et al., 2001). The challenge concentrations were 108 CFU mL−1. Half the animals were fed with 5% ginseng aqueous extracts 2 h and 30 min before intratracheal

challenge and the dosage were to equal to 0.5% of the final concentration in animal body fluid. The other half of the animals functioned as a control and only received normal saline orally at the same timepoints. Each animal received 0.04 mL of PAO1 or PAO1-filM alginate beads intratracheally into the left lung on the basis of anesthesia using a mixture of fentanyl and fluanisone (Hypnorm, 10 mg mL−1) and Midazolam (Dormicum, 5 mg mL−1) at a ratio of 1 : 1. All animals were sacrificed at 24 h after challenge and bronchial alveolar lavage (BAL) was performed within 15 min. All BAL fluids were kept at 4 °C. The animal experiment was authorized by the National Animal Ethics Committee, Denmark. BAL fluids were centrifuged to collect BAL cells. BAL smears were made and stained by Giemsa solution.