ANTIMICROBIAL EFFECT ON RABBIT SINUSITIS AFTER TEMPORARY OSTIAL OCCLUSION

A key precipitating factor in the pathogenesis of acute bacterial sinu sitis (ABS) is ostiomeatal obstruction. It has been postulated that AB S cannot resolve until the sinus ostium is patent. The primary purpose of this study is to quantify sinusitis resolution after temporary ost ial occlusion in a rabbit model. A secondary aim is to quantify bacter ial clearance with and without antimicrobial therapy in Staphylococcus aureus infected sinuses. A blinded, placebo controlled study in 10 Ne w Zealand white rabbits was performed using Merocel(R) as a temporary maxillary sinus ostial obstruction. Computerized tomography (CT) of th e maxillary sinuses was obtained before and after bilateral ostial occ lusion; sinuses were cultured and then the left sinus was injected wit h approximately 10(8) cfu/mL S. aureus. CT imaging and sinus cultures were obtained and then the ostial plugs were removed. Serial CT and cu ltures were done until sinusitis resolved and cultures were negative f or S. aureus. Mean CT sinusitis scores increased with ostial obstructi on and decreased with ostial plug removal (P < 0.0001 and P < 0.001). Injection of S. aureus did not significantly change mean CT sinusitis scores despite being cultured from 45% of sinuses. Antimicrobial thera py was not significant in reducing mean CT scan sinusitis scores or po sitive cultures. Resolution of mucosal swelling is more dependent on r elief of ostial obstruction rather than antimicrobial therapy in this rabbit model.