Evolution of Bacterial Yield and Antimicrobial Resistance in Chronic Rhinosinusitis Patients in a Dedicated Sinus Centre

ABSTRACT Background Antibiotics are frequently prescribed for acute exacerbations of chronic rhinosinusitis (CRS). However, antimicrobial resistance presents a challenge for the ongoing and future management of CRS patients. Objective This study aims to examine the current and past microbiological yield and antimicrobial resistance profile in a tertiary sinus centre. Methodology A retrospective results review for the calendar years from 2015 to 2018 and 2019 to 2024 was conducted on all CRS patients who had sinonasal microbiological samples taken during their outpatient visits with a history of previous endoscopic sinus surgery (ESS). Results A total of 706 cultures were analysed from 338 patients. Clinically significant organisms were identified in 60.0% of cases in 2015–2018 and 71.9% of cases in 2019–2024 ( p = 0.003). Whilst Staphylococcus aureus remained the predominant isolate in both groups, Gram‐negative organisms rose significantly (32.9%–46.5%, p = 0.004), particularly non‐ Pseudomonas and Enterobacteriaceae species. Interestingly, classical acute bacterial rhinosinusitis pathogens ( Staphylococcus pneumoniae , Moraxella catarrhalis , Haemophilus influenzae ) were detected in only 28.0% and 23.8% of cases in the respective study periods. Resistance to clarithromycin in S. aureus isolates increased significantly from 12.1% to 27.5% ( p = 0.0008), whilst resistance to doxycycline and amoxicillin also rose, though these changes were not statistically significant. Resistance to co‐amoxiclav increased from 0.3% to 3.2% in 2019–2024. ( p = 0.0276). Conclusion There has been an increase in the incidence of Gram‐negative bacteria as well as antibiotic resistance in CRS sinonasal cultures. These findings emphasise the importance of endoscopically guided cultures and culture‐directed antibiotic therapy when managing postoperative CRS exacerbations.