As with all skin the external auditory canal has a normal bacterial flora that remains free from infection until skin defences fail or become damaged. Some common causes that allow the overgrowth of bacteria in the external ear include:
- Swimming, perspiration, high humidity - these create excessive moisture that carry bacteria into the cerumen (ear wax) of the ear canal, leading to maceration and inflammation
- Local trauma to the ear canal allowing bacteria to enter damaged skin, e.g. insertion of objects such as cotton buds, matchsticks and fingers to relieve itching or impacted earwax
Bacteria commonly implicated in otitis externa include Pseudomonas aeruginosa and Staphylococcus aureus. In about 10% of cases of infectious otitis externa, fungal infections are the cause. The most common fungal pathogen is Aspergillus (80-90%), followed by Candida. Mixed bacterial and fungal infections are common.
Joke and Humors
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