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Published on: February 29, 2020
Hearing loss with semicircular canal fistula in exotoxin A-deficient Pseudomonas otitis media
Tariq M Yunus1, Rolando M Molina, Angela R Prevatt
1Department of Otolaryngology,University of Florida, Gainseville, FL 32610-0264, USA.
Insights
Pseudomonas aeruginosa exotoxin A significantly worsens hearing loss from semicircular canal injury during otitis media. Neutralizing this exotoxin may prevent hearing loss in chronic otitis media with canal fistula.
Area of Science:
- Otolaryngology
- Infectious Diseases
- Auditory Neuroscience
Background:
- Otitis media (OM) is a common middle ear infection.
- Semicircular canal injury can lead to hearing loss.
- Pseudomonas aeruginosa (PA) is a frequent cause of chronic OM.
Purpose of the Study:
- To compare hearing loss severity in guinea pigs with semicircular canal injury and OM.
- To investigate the role of PA exotoxin A in OM-related hearing loss.
Main Methods:
- Guinea pigs were infected with either PA+ (exotoxin A-producing) or PA- (exotoxin A-deficient) strains.
- Semicircular canal transection was performed three days post-infection.
- Hearing thresholds were measured before and after canal injury.
Main Results:
- PA+ induced OM led to significant hearing threshold elevations at click and 12 kHz.
- PA- induced OM did not cause significant hearing threshold elevations.
- Exotoxin A from PA+ was associated with greater hearing impairment.
Conclusions:
- PA exotoxin A likely mediates hearing loss associated with semicircular canal injury in OM.
- Targeting PA exotoxin A may prevent hearing loss in chronic OM with canal fistula.
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.
