Delayed hypersensitivity reaction to topical aminoglycosides in patients undergoing middle ear surgery

Repeated exposure to a topical aminoglycoside in patients with ear discharge can induce a delayed hypersensitivity reaction eventually. A postal survey conducted by the authors showed that 75% of UK otolaryngologists routinely prescribe topical aminoglycosides to their patients following ear surgery. This is a prospective study on the result of skin patch testing on 119 patients with chronic otitis media and 30 patients with otosclerosis who were scheduled for otosurgery. Any history of previous exposure to antibiotic eardrops for each patient was recorded. Overall, 14.1% of the patients had a positive skin reaction to one of the aminoglycosides (13.4% for Gentamicin; 12.8% for Neomycin and 4.5% for Framycetin). Sixteen per cent (16%) of the patients with chronic otitis media and 6.7% of the patients with otosclerosis were allergic to one of the aminoglycosides commonly found in antibiotic eardrops. Patients who received more than five courses of antibiotics eardrops previously had a greater tendency of developing allergy to the aminoglycosides (35.3%).