Bacterial exposure continued for 3 hours at 37°C,
5.0% CO2. RCEs were washed with pre-warmed PBS and then treated
with 100 L of gentamicin (0.4% [vol/vol]; 200 g/mL; BioWhittaker)
in EMEM/Hams F-12 medium for 1 hour. After another PBS wash, 100
L of Trypan blue (10% [vol/vol]) in Hams F-12 was added to the cells
and incubation continued for 15 minutes.