What is the origin of Staphylococcus aureus in the early postoperative sinonasal cavity?

Background: Despite increasing evidence of a role for Staphylococcus aureus (S. aureus) biofilms in chronic rhinosinusitis (CRS), the origin of this organism in the postsurgical sinonasal cavity had been unclear. Recently, we suggested that the increased culture rate of S. aureus following endoscopic sinus surgery (ESS) may be related to biofilm activity. This study, therefore, was designed to evaluate the origin of early postoperative sinonasal S. aureus and assess the early postoperative outcomes in patients culture-positive for this organism. Methods: Twenty-nine patients undergoing ESS for medically-recalcitrant CRS were prospectively enrolled. A comprehensive intraoperative S. aureus screening protocol was followed for all patients (including swabs for culture and tissue for fluorescence in situ hybridization [FISH] S. aureus biofilm analysis); early postoperative management included endoscopically-guided swabs for culture in all patients. Results: Twenty of 29 (69.0%) patients cultured S. aureus postoperatively, of which 17 of 20 (85.0%) were screen-positive at surgery. Seven of 11 (63.6%) intraoperatively biofilm-positive but culture-negative patients progressed to culture S. aureus post-ESS. S. aureus culture was associated with selected poorer early post-ESS outcomes. Conclusion: S. aureus persists in the sinonasal cavity despite ESS. The postoperative culture of sinonasal S. aureus in patients previously biofilm-positive but culture-negative may reflect the dynamic ability of S. aureus to adapt to the surgically-altered microenvironment with subsequent biofilm dispersal and release of planktonic clones.