The bacteriology of recurrent acute exacerbations of chronic rhinosinusitis: a longitudinal analysis.

Purpose: The purpose of this study was to describe the microbiology of recurrent acute exacerbations of chronic rhinosinusitis over time.
Methods: Retrospective review of patients with recurrent acute exacerbations of chronic rhinosinusitis who underwent endoscopic-guided cultures during acute exacerbations of chronic rhinosinusitis.
Results: 386 cultures were obtained from 112 patients during recurrent acute exacerbations of CRS. A change of bacterial isolates during the course of recurrent exacerbations was observed in 68% (76/112) of patients, necessitating a change of treatment in 40% (45/112). The main risk factor for the subsequent change in cultures was polymicrobial growth. Sinus surgery was not associated with subsequent change in cultured isolates. Resistant strains developed in 11.6% (13/112) of patients, of whom those with abnormal mucociliary clearance being at the highest risk.
Conclusion: Repeated middle meatal cultures should be considered in patients with recurrent exacerbations of CRS, particularly in cases not responding to standard therapy.