Chronic bacterial rhinosinusitis - Description of a mouse model

Objectives: To survey normal murine sinonasal anatomy and to create a mouse model for chronic bacterial rhinosinusitis. Design: Anatomic, histologic, and pathophysiologic study displaying normal murine sinonasal anatomy and surgically created unilateral sinonasal inflam mation. Subjects: Twenty-one 6-week-old, male C57BL/6 mice. Interventions: Animals that underwent unilateral maxillary sinus ostial obs truction using Merocel nasal packing, animals with unilateral Bacteroides f ragilis inoculation alone, and animals with both ostial obstruction and bac terial inoculation were examined at 4 weeks for histologic evidence of chro nic sinonasal inflammation. Experimental interventions were compared with c ontralateral control sinuses within each animal and with normal and sham-op erated controls. Results: Normal mouse paranasal sinuses include maxillary sinuses, ethmoid air cells, and respiratory-type epithelium. In experimental animals, the la teral maxillary sinus wall, nasal septum, and superior turbinelle of the ma xillary sinus were examined histologically. Epithelial thickening and disar ray, goblet cell hyperplasia, inflammatory infiltrates, and sinonasal fibro sis were present in the experimental sinuses of animals packed with Merocel alone or Merocel with bacterial inoculation. Changes seen with Merocel and bacteria were more dramatic than those with Merocel alone. Sham-operated c ontrols and sinuses inoculated with bacteria alone did not differ significa ntly from the sinuses of normal animals. Conclusion: Unilateral maxillary sinus ostial obstruction using Merocel nas al packing along with B fragilis inoculation results in a persistent, local ized bacterial rhinosinusitis in mice.