Most Common Pathogens Causing Rhinosinusitis in Patients Who Underwent Endoscopic Sinus Surgery Before, During, and After the COVID-19 Pandemic.

Importance: Chronic rhinosinusitis (CRS) significantly impacts patients' quality of life and incurs substantial healthcare costs. Understanding pathogen trends before, during, and after the COVID-19 pandemic can inform better management and treatment strategies.

Objective: To identify the common pathogens associated with CRS and compare them across pre-pandemic, during-pandemic, and post-pandemic periods.

Design: Retrospective chart review.

Setting: McGill University Health Centre, Montreal, Canada.

Participants: Around 147 patients were 18 years and older, diagnosed with CRS, underwent endoscopic sinus surgery within the specified timeframe (January 2017 to September 2023), and whose charts contained relevant microbiology information. Patients were categorized into 3 groups based on surgery dates: pre- (January 2018 to November 2019), during- (January 2020 to December 2021), and post-pandemic (February 2022 to September 2023).

Main outcome measures: Distribution and prevalence of pathogens associated with CRS across the 3 time periods. Microbiology results from nasal cultures were analyzed to identify predominant pathogens.

Results: Among the 147 patients, 46 distinct organisms were identified. Staphylococcus aureus was the most prevalent pathogen, increasing during the COVID-19 period (24.7%) compared to pre-pandemic (17.9%) and post-pandemic (21.5%) periods. Significant increases during the COVID-19 period were noted for Aspergillus fumigatus (6.8%, P < .001), Enterobacter cloacae (6.8%, P = .01), and Cutibacterium acnes (6.8%, P = .03). Post-pandemic, significant rises were observed in Serratia marcescens (P < .001) and Achromobacter denitrificans (P = .03).

Conclusions and relevance: Significant shifts in CRS-associated pathogens occurred during the COVID-19 pandemic. Notable changes in the prevalence of S. aureus, A. fumigatus, E. cloacae, and C. acnes were observed during the pandemic, with increases in S. marcescens and A. denitrificans post-pandemic. These findings suggest that the pandemic's impact on healthcare practices and environmental factors influenced the microbial etiologies of CRS. Future research may explore the mechanisms driving these changes and their long-term implications for CRS management.