NFECTION of the external auditory canal and chronic infection of the middle ear that has failed to resolve comprise two widely encountered clinical entities. In the case of the former, external otitis constitutes anywhere from 5 to 40% of all ear infections seen in the United States, the wide variation being due to regional and sectional differences in atmospheric temperature and humidity.
Judicious selection of medicaments for the treatment of external otitis, the more common types of which include furunculosis, otomycosis, and eczematous dermatitis, often depends on the bacteriology of the infectious process. The causative agent of external otitis can be any one of a number of gram-positive or gram-negative bacteria and fungi. In troublesome cases, antibiotic sensitivity testscan aid in the selection of the most effective antimicrobial drugs for use in therapy. These tests, however, are not foolproof, and their interpretation requires experience and judgment for proper evaluation.