The multiplicity of Staphylococcus aureus in chronic rhinosinusitis: correlating surface biofilm and intracellular residence.

OBJECTIVES/HYPOTHESIS: The biofilm paradigm of chronic rhinosinusitis (CRS) is increasingly understood to play a key role in the pathophysiology of this disease. The role of intracellular infection of sinonasal epithelial cells has been suggested as a potential reservoir of pathogenic organisms that can lead to recalcitrant disease despite maximal medical and surgical treatment. Could a surface biofilm play a role in allowing intracellular infection to occur, and what are the factors associated with potential intracellular infections? The aim of this study was to investigate these questions. STUDY
DESIGN: A prospective study including 36 CRS patients undergoing endoscopic sinus surgery and five control patients undergoing endonasal pituitary surgery.
METHODS: Sinonasal mucosa harvested at the time of surgery was examined with a Staphylococcus aureus fluorescence in situ hybridization probe and propodium iodide counterstain using the confocal scanning laser microscope for both biofilm status and evidence of intracellular organisms.
RESULTS: Intracellular S aureus was identified in 20/36 (56%) CRS patients compared to 0/8 (0%) control patients. CRS patients with intracellular infection were significantly more likely to harbor surface biofilm (20/20, P = .0014) and have a S aureus-positive culture swab (12/20, P = .0485).
CONCLUSIONS: This study gives further evidence supporting a role of intracellular S aureus in CRS. In all cases intracellular infection was associated with surface biofilm, suggesting a potential relationship between the two. Further work is required to delineate the true mechanisms of intracellular persistence and also the role that it plays in the recalcitrant nature of CRS.