Bacteriology of Noneosinophilic vs Eosinophilic CRS With Nasal Polyps

x ray of sinusitis and nasal polyps
Do differences in bacteria cultures between noneosinophilic and eosinophilic CRSwNP relate to differences in disease severity?

Patients with noneosinophilic chronic rhinosinusitis with nasal polyps (CRSwNP) have a significantly higher gram-negative aerobic culture rate compared with patients with eosinophilic CRSwNP, according to study results presented at the American Academy of Otolaryngology-Head and Neck Surgery Foundation (AAO-HNSF) 2022 Annual Meeting and OTO Experience, held in Philadelphia, Pennsylvania, September 10 to 14, 2022.

Eosinophilic CRS, a subtype of recalcitrant CRS, generally has worse disease severity and poorer treatment outcomes than noneosinophilic CRS. Notably, bacteria have been hypothesized as having vital roles in CRS pathogenesis. To test this hypothesis, researchers compared disease severity by evaluating culture results between patients with either noneosinophilic or eosinophilic CRWSwNP who underwent primary bilateral functional endoscopic sinus surgery. Before surgery, patients underwent an endoscopic examination, a computed tomography scan, and had swab samples taken from the middle meatus to obtain bacterial cultures for determining CRS severity.

A total of 295 patients with a confirmed diagnosis of nasal polyps were enrolled in the study. Analysis of both sides of these patients’ nasal cavities showed polyps in a total of 471 sides of the nasal cavity that were categorized as either noneosinophilic (n=235) or eosinophilic (n=236). A tissue eosinophil count of more than 10 cells per high power was used to distinguish CRS as either eosinophilic or noneosinophilic. The specimens were sent for evaluation of tissue eosinophilia after surgery.

Among the included patients, bacteria grew in 88 of the 235 noneosinophilic sides and in 94 of the 236 eosinophilic sides. There was a significantly higher Lund-Kennedy endoscopic score among the noneosinophilic sides of the nasal cavity compared with eosinophilic sides (P <.001). However, noneosinophilic and eosinophilic sides were not considered significantly different (P =.611).

Additionally, although gram-negative aerobes were cultured from both CRSwNP sides, the culture rate between the noneosinophilic (42 of 235) and eosinophilic (25 of 236) groups was not considered significantly different (P =.662). The noneosinophilic group had a significantly higher gram-negative aerobic culture rate compared with the eosinophilic group (P =.033).

The researchers determined the study “showed that the bacteriology of CRS with nasal polyps was different between [eosinophilic CRSwNP] and [noneosinophilic CRSwNP],” with gram-negative aerobes more present in patients with noneosinophilic CRSwNP.


Jiang R-S, Liang K-L. Comparison of bacteriology between eosinophilic and noneosinophilic chronic rhinosinusitis with nasal polyps. Otolaryngol Head Neck Surg. 2022;167(1 suppl):P142.