Acute Otitis Externa (Swimmer’s Ear): Pathogenesis and clinical findings

Pathogens = Pseudomonas aeruginosa (most common opportunistic), Staphylococcus, other gram negatives

Risks: Immunocompromized (HIV, diabetes), Swimmers



1. Absence of cerumen - Aggressive washing of cerumen or retention of water -> Alkalotic external auditory canal -> Decreased production of antibacterial agents (e.g. lysozyme) -> Bacterial overgrowth

2. Trauma - Microtraumas (e.g. cotton swaps, finger nails, or hair pins) -> Injury of external auditory canal soft tissue -> Invasion of bacteria into damaged skin

3. Obstruction - Cerumen build-up, debris, exostosis, narrow and tortuous auditory canal -> Moist, dark, warm environment of the external auditory canal -> Pathogen overgrowth



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