Reduction of endotoxin-induced inflammation of the middle ear by polymyxin B.

Endotoxin (ET) is an aggregate of lipo-oligosaccharide and protein found in the cell wall of gram-negative bacteria. A potent mediator of inflammatory responses, ET has been detected in middle ear effusions from patients with otitis media with effusion and chronic suppurative otitis media and used to induce inflammation of the middle ear mucosa and disruption of mucociliary transport in experimental animals. Polymyxin B, a polypeptide antibiotic, has been shown to bond to and inactivate the ET molecule. This study investigated the efficacy of polymyxin B as a modulator of the inflammatory response to endotoxin in the middle ear. In a guinea pig model, cellular infiltrate, effusion volume, and mucosal edema in response to ET were reduced in the presence of polymyxin B. These results suggest a potential role for the use of polymyxin B in the management of middle ear effusion.