BackgroundChronic rhinosinusitis (CRS) can be difficult to treat medically secondary to crusting and biofilms resistant to oral antibiotics. Treatment with topical antibiotics has grown in popularity due to their ability to administer a high local drug concentration while mitigating systemic effects. Published literature on topical antibiotic efficacy for CRS is mixed and sparse.ObjectiveTo describe the efficacy of postoperative topical mupirocin rinses in reducing objective and subjective markers of CRS disease severity.MethodsPatients with suspected biofilm formation following functional endoscopic sinus surgery who were treated with mupirocin 15 mg or 30 mg rinses twice daily between 2018-2023 were included. These patients' symptoms and endoscopic findings were refractory to high-volume steroid irrigations and oral antibiotics. Data collected involved comorbidities, rinse duration, concurrent therapies, Lund-Kennedy (LK) scores, sino-nasal outcome test-22 (SNOT) scores, and adverse effects. LK and SNOT scores were compared across 3 time points (preoperative, 3-month-postoperative-prerinse, postrinse) using one-way analysis of variance and Wilcoxon rank sum for pairwise comparisons.ResultsThirty patients were included. Average age was 63.3 years, 66.7% of patients were female, and 60% had nasal polyposis. There was a statistically significant decrease in LK scores between the 3-month-postoperative-prerinse period and the postrinse period (-0.92 ± 1.25