Patients with severe, chronic otitis externa are commonly secondarily infected with Pseudomonas aeruginosa; in those cases, the otitis externa has usually progressed and otitis media is present as well. Otitis media can be a perpetuating factor for otitis externa and can prevent its resolution. Otitis media cases require long courses of systemic antibiotics with the use of culture and susceptibility to guide therapy. Because the ear drum typically grows back when ruptured, an intact ear drum does not rule out otitis media. If the ear drum is intact, a myringotomy is required to culture the bulla and treat the condition. The bulla should be thoroughly flushed under general anesthesia using sterile saline. Topical steroids are frequently used to minimize inflammation and any neurologic signs after a deep ear flush. Oral steroids or other analgesics also may be indicated following an ear flush.
Topical therapy for P aeruginosa should include Tris-EDTA, which binds to calcium in the cell wall of the bacteria. This weakens the cell wall and increases the effectiveness of topical antibiotic solutions. Other topical therapies may include orbifloxacin, enrofloxacin, ticarcillin/clavulanic acid, and silver sulfadiazine. Ototoxicity has not been reported from silver-based solutions in cases of otitis media with P aeruginosa.—Marsella R