A biofilm exists on healthy mucosa of the paranasal sinuses: a prospectively performed, blinded, scanning electron microscope study.

Objectives: Based on our hypothesis that biofilm is nothing else but normal, otherwise abundantly colonised mucosal mucous blanket, the aim of this study was to check out whether bacterial biofilm exists exclusively at the diseased mucosal surfaces or at healthy mucosa of paranasal sinuses as well.

Design: Prospective and blinded.

Setting: Tertiary academic hospital.

Participants: The patients suffering from the diseases not related to the chronic inflammation of the paranasal sinuses. Mucosal tissue samples from healthy sphenoid sinuses were taken from 48 patients who underwent pituitary gland surgery and from ethmoidal sinuses mucosa of the 17 patients who underwent endonasal endoscopic orbital decompression because of Graves' disease.

Main Outcome Measures: The samples were submitted blindly along with similar samples from patients with chronic rhinosinusitis to two scanning electron microscope experts. In all samples the looked for the main signs of biofilm presence of: the 'towers', rod-shaped bacteria and water channels.

Results: Signs of biofilm presence were found in 45 out of 48 pituitary gland surgery patients (94%) and in all of 17 EEOD patients (100%).

Conclusions: Our study showed the presence of the biofilm at the surface of the healthy mucosa of the paranasal sinuses. This suggests that perhaps so called bacterial biofilm is nothing else but regular respiratory mucosal blanket, a part of the mucociliary system itself, containing a great number of bacteria.