Mucus collection technique
Mucus samples were taken at each time point. At time point -2, samples were taken before the washout period. At time point 0, samples were taken after the 4-week washout period. At all other time points, samples were taken prior to antibiotic or steroid administration. Samples were taken by applying a polyvinyl alcohol sponge (PVA, Medtronic, Minneapolis, MN) to the anterior internal valve, taking care not to abrade the mucosa or contaminate the sponge with blood. The sponges were weighed prior to and after insertion into the nose. Then, the sponge was soaked with 3 ml of PBS. After 10 minutes, the sponges were centrifuged for 10 minutes at 2000 xg. The eluate was frozen immediately into aliquots at -80°C and was stored at -80°C until analysis.