THE SUMMER SEASON invariably brings an increased incidence of external otitis. Most cases are bacterial in origin and generally of low virulence. The condition is prone to recur because of the peculiar structure of the auditory canal, which permits water and foreign material to enter and be retained.
In about 70% of cases of external otitis, the predominant organism is Pseudomonas aeruginosa, a gram-negative organism. The remainder includes Staphylococcus aureus, Staph. albus, Diphtheroids, Escherichia coli, Proteus vulgaris, and a number of others.Maceration of the skin of the canal from water, trauma from foreign objects (particularly of organic character), and moist climatic conditions favor growth of fungi. Fungus infections of the external auditory canal have always presented a problem, since fungi resist most of the commonly used otitis preparations. Contrary to the layman's belief, however, most cases of so-called "fungus ear" are in reality bacterial infections, and fungi—when present—are
Jenkins BH. Treatment of Otitis Externa and Swimmer's Ear. JAMA. 1961;175(5):402-404. doi:10.1001/jama.1961.63040050008021b