Characterization of bacterial and fungal biofilms in chronic rhinosinusitis.

Background: Conclusive evidence exists that biofilms are present on the mucosa of chronic rhinosinusitis (CRS) patients. Less is known about the species constituting these biofilms. This study developed a fluorescence in situ hybridization (FISH) protocol for characterization of bacterial and fungal biofilms in CRS.
Methods: Fifty CRS patients and 10 controls were recruited. Bacteria FISH probes for Staphylococcus aureus, Haemophilus influenzae, and Pseudomonas aeruginosa and a universal probe for fungi were applied to sinus mucosal specimens and then analyzed using confocal scanning laser microscopy.
Results: Thirty-six of 50 CRS patients had biofilms present in contrast to 0/10 controls, suggesting a role for biofilms in the pathogenesis of this disease. S. aureus was the most common biofilm-forming organism. Eleven of 50 CRS patients had characteristic fungal biofilms present.
Conclusion: This is the largest study of biofilms in CRS. It has validated mucosal tissue cryopreservation for delayed biofilm analysis. Fungal biofilms have been identified and the importance of S. aureus biofilms in the polymicrobial etiology of CRS is highlighted.