- Acute otitis externa (AOE) is a cellulitis of the ear canal skin and subdermis, with acute inflammation and variable edema.
- Also known as swimmer’s ear or tropical ear, AOE is one of the most common infections encountered by clinicians, with regional variations based on age and geography.
- In 2007 there were about 2.4 million visits to ambulatory care centers and emergency departments for AOE (8.1 visits per 1000 population), affecting 1 in 123 persons in the United States.
- Just less than half of all visits were for children 5-14 years of age.
- Lifetime incidence is up to 10%.
- AOE is more common in regions with warmer climates, increased humidity, or increased water exposure from swimming.
- Nearly all (98%) AOE in North America is bacterial.
- The etiology of AOE is multifactorial.
- Regular cleaning of the ear canal removes cerumen, which is an important barrier to moisture and infection.
- Debris from dermatologic conditions may also encourage infections, as can local trauma from attempts at self-cleaning, irrigation, and wearing hearing aids.
- Other factors such as sweating, allergy, and stress have also been implicated in the pathogenesis of AOE.
- The most common pathogens are Pseudomonas aeruginosa (20%-60% prevalence) and Staphylococcus aureus(10%-70% prevalence), often occurring as a polymicrobial infection.
- Topical antimicrobials are beneficial for AOE, but oral antibiotics have limited utility.
Table 1. Elements of the Diagnosis of Diffuse Acute Otitis Externa
|1. Rapid onset (generally within 48 hours) in the past 3 weeks, AND…|
|2. Symptoms of ear canal inflammation, which include:|
|3. Signs of ear canal inflammation, which include:|
Table 2. Summary of Evidence-based Statements
|1. Differential diagnosis||Clinicians should distinguish diffuse AOE from other causes of otalgia, otorrhea, and inflammation of the external ear canal.||R-C/D|
|2. Modifying factors||Clinicians should assess the patient with diffuse AOE for factors that modify management (nonintact tympanic membrane, tympanostomy tube, diabetes, immunocompromised state) prior radiotherapy.||R-C|
|3. Pain management||Clinicians should assess patients with AOE for pain and recommend analgesic treatment based on the severity of pain.||S-B|
|4. Systemic antimicrobials||Clinicians should NOT prescribe systemic antimicrobials as initial therapy for diffuse, uncomplicated AOE unless there is extension outside the ear canal or the presence of specific host factors that would indicate a need for systemic therapy.||S-B|
|5. Topical therapy||Clinicians should use topical preparations for initial therapy of diffuse, uncomplicated AOE.||R-B|
|6. Drug delivery||Clinicians should instruct patients how to administer topical drops and should enhance delivery of topical drops when the ear canal is obstructed by performing aural toilet, placing a wick, or both.||R-C/D|
|7. Nonintact tympanic membrane||When the patient has a known or suspected perforation of the tympanic membrane, including a tympanostomy tube, the clinician should recommend a non-ototoxic topical preparation.||R-D|
|8. Outcome assessment||If the patient fails to respond to the initial therapeutic option within 48-72 hours, the clinician should reassess the patient to confirm the diagnosis of diffuse AOE and to exclude other causes of illness.||R-C|
Table 3. Common Topical Otic Preparations Approved by the Food and Drug Administration for Treating Diffuse AOE
|Active Drugs(s)||Name||Bottle Size, mL||Cost, US$a|
|Acetic acid 2.0% solution||Acetic acid otic (generic)||15.0||—||33|
|Acetic acid 2.0%,|
|Acetasol HC (generic)||10.0||—||23|
|Cipro HC® (trade)||10.0||170||—|
|Neomycin, polymyxin B,|
|Cortisporin Otic® (trade)||10.0||85||30|
|Ofloxacin 0.3%||Floxin Otic® (trade)||5.0||76||18|
Table 4. Instructions for Patients
- If possible, get someone to put the drops in the ear canal for you.
- Lie down with the affected ear up. Put enough drops in the ear canal to fill it up.
- Once the drops are in place, stay in this position for 3-5 minutes. Use a timer to help measure the time. It is important to allow adequate time for the drops to penetrate into the ear canal.
- A gentle to-and-fro movement of the ear will sometimes help in getting the drops to their intended destination. An alternative method is to press with an in/out movement on the small piece of cartilage (tragus) in front of the ear.
- You may then get up and resume your normal activities. Wipe off any excess drops.
- Keeping the ear dry is generally a good idea while using eardrops.
- Try not to clean the ear yourself as the ear is very tender and you could damage the ear canal or even the eardrum.
- If the drops do not easily run into the ear canal, you may need to have the ear canal cleaned by your clinician or have a wick placed in the ear canal to help in getting the drops into the ear canal.
- If you do have a wick placed, it may fall out on its own. This is a good sign. It means the inflammation is clearing and the infection subsiding.
- Do not remove the wick yourself unless instructed to do so.
Table 5. Patient Information for Topical Therapy of AOE
|Frequently Asked Question||Answer|
|Are eardrops alone sufficient to treat my infection, or do I also need to take an antibiotic by mouth?||Eardrops alone are the most effective treatment for AOE and may contain antibiotics, antiseptics, steroids, or a combination. Antibiotics taken by mouth do not kill most germs that cause AOE and should be used only when infection spreads beyond the ear canal, eardrops cannot get into the ear, or the immune system is weak.|
|Which eardrop is best for treating my ear infection?||All eardrops approved for treating AOE (Table 3) are highly effective, with no consistent advantage shown for any one specific drug.|
|If all eardrops are equally effective, why do doctors prescribe different ones?||Your doctor will discuss with you the reasoning behind his or her eardrop recommendation, but some of the factors considered include cost, dosing frequency, status of the eardrum, and the doctor’s experience. Your opinion and preferences should also factor into this decision.|
|Is there anything I should be sure to tell my doctor that might help in deciding which eardrop is best?||Let your doctor know if you had any prior ear surgery, if there is an opening (hole or perforation) of the eardrum, or if an ear tube is in place. If 1 or more of these conditions apply, then your doctor will need to use an eardrop that is approved for use in the middle ear, just in case some of it gets past the eardrum. Also let your doctor know if you have recently used other ear products or medications or if you have had a reaction in the past to a particular eardrop or antibiotic. Last, tell your doctor if you have, or are suspected to have, diabetes, since this could alter management.|
|Once I start using the eardrops, how long should it take until I feel better?||Most people feel better within 48-72 hours and have minimal or no symptoms by 7 days. Notify your doctor if your pain or other symptoms fail to respond within this time frame.|
|If it usually takes at least 48 hours to feel better from the eardrops, what should I do for earlier relief?||Pain medicine is especially important to use for relief in the first few days, until the eardrops begin working. Discuss with your doctor which pain medicines are best for you. Pain-relieving (anesthetic) eardrops are not recommended because they are not intended for use during an active ear canal infection and can mask symptoms of a delayed response to therapy.|
|For how long will I need to use the eardrops?||Eardrops should be used for at least 7 days, even if you feel better sooner, to prevent relapse of infection. If symptoms persist beyond 7 days, you should notify your doctor and continue the drops until the symptoms resolve for a maximum of 7 additional days.|
|Are there any activity restrictions or special precautions that will help my ear recover faster?||Avoid scratching or touching the ear, and do not insert anything into the ear canal, including cotton-tipped swabs. Cover the opening of ear canal with an earplug or cotton (with petroleum jelly) prior to showering or hair washing to minimize water entry. Check with your doctor regarding swimming or other water activities that may take place during, or soon after, your infection.|
|Do eardrops have side effects that I should be aware of?||Eardrops are, in general, very safe and well tolerated. Some people report local rash, itching, irritation, or discomfort, but it is rarely bad enough to require stopping the medication. If you taste the eardrops, it means there is likely a hole or perforation of the eardrum, so inform your doctor (if you have not already done so). Also call your doctor if the drops become painful or you develop unexpected symptoms.|