Managing Acute Otitis Externa: The Latest Guidelines

Topical Treatment Options

Ototopical medications are considered first-line therapy for AOE. Several classes of medications are available for use, including antibiotics (eg, fluoroquinolones, aminoglycosides, and polymyxin B), steroids (eg, dexamethasone and hydrocortisone), and antiseptics (eg, acetic acid and boric acid). Three major meta-analyses have compared the relative efficacies of these various classes of drugs for AOE. Rosenfeld and colleagues^[10] and Kaushik and colleagues^[5] concluded that there were few clinically meaningful differences among ototopical compounds. Mösges and colleagues^[11] determined that medications containing both antibiotics and steroids were superior to those containing antibiotics alone when measuring improvement of clinical presentation and eradication of microbes; however, it should be noted that this study was funded in part by a pharmaceutical company that manufactures the drugs that were included in the meta-analysis. Because outcomes are generally similar among ototopical medications, the decision to select a particular medication may be informed heavily by such factors as patient preference, cost, treatment adherence, adverse effects, and provider experience.

For uncomplicated AOE with an intact tympanic membrane, all of the choices listed above are reasonable. Neomycin/polymyxin B/hydrocortisone is often an initial selection owing to its relatively low cost and reasonable effectiveness.^[4] However, the medication has three critical features of which providers and patients should be aware. First, the AAO-HNSF clinical practice guideline on AOE, the UK Committee on Safety of Medicines, and the Medicines Control Agency recommend using a medication that is non-ototoxic for patients with non-intact tympanic membranes.^[3,12] Animal models consistently demonstrate that aminoglycosides are ototoxic when instilled into the middle ear.^{[13,14,15,16]} Furthermore, analysis of Medicaid claims data suggests that repeated use of aminoglycoside-containing eardrops may be associated with an elevated risk for sensorineural hearing loss.^[17] Black box warnings exist on ototopical aminoglycoside labels about the risk for ototoxicity.^[3,16] Second, 15% of patients can develop contact dermatitis after exposure to neomycin therapy,^[5] which can present similarly to AOE (eg, pruritus). The rate of contact dermatitis can be as high as 30%-60% of patients with chronic or eczematous external otitis.^[3] Finally, neomycin/polymyxin B/hydrocortisone is generally administered three to four times daily, a higher frequency than with fluoroquinolone formulations, which may contribute to poorer patient adherence.

Antiseptic and alcohol-containing compounds also are not recommended by the AAO-HNSF if patients have tympanic membrane perforations, owing to the risk for pain and potential ototoxicity. However, fluoroquinolone-containing medications are approved by the US Food and Drug Administration for middle ear use. Moreover, they are administered once to twice daily, which may be more tolerable to patients. Thus, fluoroquinolone eardrops are ideal selections for use in patients with AOE and non-intact tympanic membranes. Their primary drawback is the relatively high cost: more than $100 per bottle for most formulations.^[3,4]

Delivery of ototopical medications is enhanced by aural toilet of the obstructed ear canal, using suction or blotting with a cotton-tip applicator, under direct visualization with an otoscope or binocular microscope. Gentle lavage with saline, distilled water, or hydrogen peroxide may be considered only if the patient has an intact tympanic membrane; this should be avoided in patients with diabetes because of the risk of inducing malignant otitis externa.^{[3,4,18,19,20]} Use of a wick (eg, cellulose or ribbon gauze) can help expand an edematous canal and facilitate delivery of medication. Patient education on the proper techniques for instilling ototopical medications is also critical to successful treatment. Patients should avoid water sports and limit the use of devices placed in the ear, such as hearing aids and earphones, during therapy. Patients should also be instructed on how to safely dry their ears (ie, using a hair dryer set on the lowest power setting).^[3,4]

Fourth Case: Systemic Therapy for AOE

A 21-year-old college student visited her college health center with a 5-day history of bilateral ear itchiness and drainage during and after a trip with friends for spring break. She stated that the symptoms began a day or so after swimming in a resort pool. The patient admitted to using cotton-tip applicators to help dry her ears out after swimming. The patient reported no other symptoms. Her examination demonstrated tenderness of both auricles and tragi and bilateral external auditory canal edema and erythema. The tympanic membranes were intact. The patient was diagnosed with bilateral AOE, and ototopical therapy was initiated.

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