Hearing Loss with Semicircular Canal Fistula in Exotoxin A-Deficient Pseudomonas Otitis Media

Abstract

OBJECTIVE: The study goal was to compare the severity of hearing loss with semicircular canal injury in the presence of otitis media (OM) due to an exotoxin A-producing strain of Pseudomonas aeruginosa (PA+) and an exotoxin A-deficient daughter strain (PA-). METHODS: PA+ or PA- was injected bilaterally into guinea pig ears. Three days later, unilateral lateral semicircular canal transection was performed. Hearing was tested before and after transection. RESULTS: PA OM was induced in all injected ears. Significant elevation of click and 12-kHz thresholds ( P < 0.0001) were encountered in PA+-infected ears. No significant threshold elevations were encountered in PA-infected ears. Conclusion: Hearing loss resulting from canal injury in the presence of Pseudomonas OM may be mediated by exotoxin A. SIGNIFICANCE: Treatment to neutralize the effects of exotoxin A may minimize the risk of hearing loss with canal fistula in chronic OM.