EFFECT OF SYSTEMIC PRETREATMENT WITH BETAMETHASONE ON THE BACTERIAL-FLORA, INFLAMMATORY RESPONSE, AND POLYP FORMATION IN EXPERIMENTALLY INFECTED-RABBIT MAXILLARY SINUS MUCOSA

To investigate possible effects of corticosteroids on polyp formation and local bacterial colonization, pneumococcal sinusitis was experimen tally induced in rabbits pretreated with betamethasone or saline. Afte r 7 days, macroscopic polyps were counted postmortem and on histologic slides after serial sectioning. Histologic sections were also examine d with light microscopy. Macroscopic polyps were significantly fewer i n animals given betamethasone, while there was no difference regarding the number of microscopic polyps. Ingrowth of pathogenic microorganis ms was found in five of eight rabbits given placebo but in none of the animals treated with corticosteroids (P < 0.05). The reduced number o f pathogenic strains in these animals may be explained by a better-pre served local host defense. The lower number of macroscopic polyps in t he same animals could be because of a delayed mucosal repair and subse quent polyp formation.