otitis externa, inflammation or infection of the external canal or the auricle of the external ear. Major causes are allergy, bacteria, fungi, viruses, and trauma. Allergy to nickel or chromium in earrings and to chemicals in hair sprays, cosmetics, hearing aids, and medications, particularly sulfonamides and neomycin, is common. Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pyogenes are common bacterial causes. Herpes simplex and herpes zoster viruses are frequently implicated. Eczema, psoriasis, and seborrheic dermatitis also may affect the external ear. Abrasions of the ear canal may become infected, and excessive swimming may wash out protective cerumen, remove skin lipids, and lead to secondary infection. Otitis externa is more prevalent during hot, humid weather. Folliculitis is particularly painful in the external auditory meatus and is a common occupational hazard in nurses, caused by irritation from the earpieces of stethoscopes. Treatment includes oral analgesics, thorough local cleansing, topical antimicrobials to treat infection, and topical corticosteroids to reduce inflammation. Prevention includes measures to avoid trauma and to reduce maceration of the skin.
