Experimentally Induced Polyps in the Rabbit Maxillary Sinuses: Effects of Different Bacterial Infections with or without Mechanical Trauma on Polyp Formation

Hong, Soon Kwan

Abstract

BACKGROUND AND OBJECTIVES: Many studies have been made on sinonasal polyps to elucidate their pathogenesis, definition and treatment. However, recently reported animal polyp studies provided only a few comparative results of polyp formation under various conditions. The aim of this study is to develop an animal model of polyps that is more suitable for further polyp studies by semi-quantitatively analyzing the effects of different bacterial infections with or without mechanical trauma to the rabbit maxillary sinus (MS) mucosa on polyp formation.
MATERIALS AND METHODS
The natural ostia of the right MSs were occluded in 40 Pasteurella-free New Zealand white rabbits. The left MSs were used as control. All rabbits were divided into four groups according to different manipulations on the right MSs; Streptococcus pneumoniae was inoculated without brushing the mucosa (group A) and with brushing (group B), Pseudomonas aeruginosa was inoculated without brushing (group C) and with brushing (group D). After four weeks, macroscopic polyps and light microscopic polyps and/or polypoid mucosa were semi-quantitatively analyzed.
RESULTS
The number of macroscopic polyps per sinus of group A was significantly smaller than those of groups B, C and D. Microscopic examination revealed significantly higher levels of polyps and/or polypoid mucosa in group B than in group A, but significantly lower levels in group B than in groups C and D.
CONCLUSION
P. aeruginosa infection of the rabbit MS proved more beneficial to polyp formation than S. pneumoniae infection, regardless of mechanical trauma to the sinus mucosa. However, for the inoculation of MS with S. pneumoniae, it was more beneficial to poly induction if the mucosa was mechanically traumatized.