Activity of nasal amphotericin B irrigation against fungal organisms in vitro

Background: The role of fungi in chronic rhinosinusitis has been described in recent reports. Controversy exists on the use of topical amphotericin B therapy as a treatment modality for this condition. The effect of various concentrations of amphotericin B nasal irrigation on actively growing fungi was studied in vitro. Methods: Ten species of fungi commonly found in the nasal cavity were grown on growth media plates. Each fungi was exposed to 20 mL of amphotericin B nasal irrigation at concentrations of either 100, 200, or 300 mu g/mL, or sterile water two times daily for 6 weeks. Each plate was subcultured on a weekly basis to examine for any viable fungi. Results: Fungi growth was not arrested in the 100-mu g/mL amphotericin B and sterile water groups at the end of 6 weeks. Use of the 300- and 200-mu g/mL amphotericin B solutions showed failure of the subcultured fungi to grow at 5 and 6 weeks, respectively. Conclusion: Nasal amphotericin B irrigation is ineffective in killing fungi in vitro at a concentration of 100 mu g/mL over a 6-week period. Concentrations of 200 and 300 mu g/mL successfully prevented fungi growth at the conclusion of the study. The current concentration Of commercially available topical amphotericin B (100 mu g/mL) seems ineffective in eradicating fungi in vitro.