Approach

The main goals of treatment are to control pain, cure infection, and prevent recurrence. Treatment is usually given as for bacterial infection initially. Treatment for fungal infection is given if there are visual signs of fungal growth, or if presumptive bacterial treatment has failed. Prior to the use of topical ear drops, the ear canal needs to be cleaned of any debris or wax by dry swabbing or microsuction.[18]​ This allows the status of the tympanic membrane to be checked as well as enhancing skin penetration of the topical solution.[18]​ When using ear drops, advise the patient to apply the drops lying down with the affected ear upward and wait for 5-10 minutes before getting up.

Presumed bacterial infection: initial treatment in otherwise healthy people

In people who do not have other medical issues such as diabetes, HIV/AIDS, other immunocompromised states, or a history of radiation therapy, and who do not have signs of fungal infection or necrotizing otitis externa, initial presumptive treatment is with topical antibacterial ear drops, plus analgesia.[1] Prior to the use of topical ear drops, the ear canal needs to be cleaned of any debris or wax by dry swabbing or microsuction.[18]​ Patients who have severe swelling of the ear canal may have difficulty using ear drops. A wick should be inserted in the ear canal to allow for drug delivery. 

Several ear drops are available for first-line treatment. Studies have failed to demonstrate difference in outcome with different products.[1][30] The choice of the ear drop should be based on patient preference, and the clinician's experience, taking into account efficacy, low incidence of adverse events, likelihood of adherence to therapy, and cost.[1]

One of the early treatments consisted of topical acetic acid, and a 2007 study confirmed trichloroacetic acid as an effective and safe treatment for acute otitis externa.[31]

Currently, topical antibiotic solutions are more commonly used in acute otitis externa (AOE).[32][33]​​ Neomycin- and polymyxin B-containing solutions were one of the first antibiotic ear drops to be used and demonstrated efficacy against pathogens causing AOE.[34] The addition of a corticosteroid to such preparations was found to hasten symptomatic relief.[35] However, solutions containing neomycin, polymyxin-B, or hydrocortisone are to be avoided in patients with tympanic membrane perforation due to potential ototoxicity.[1][12]​​[32]

Fluoroquinolone-containing (ciprofloxacin and ofloxacin) agents have become available and are effective against both gram-negative and gram-positive pathogens that are common in otitis externa.[32][36][37]​​ In one systematic review, a combined ciprofloxacin/dexamethasone preparation was found to be safe and effective in patients with AOE.[38] One meta-analysis found that fluoroquinolone-containing ear drops are superior to combination drugs not containing a fluoroquinolone.[39] Hypersensitivity to fluoroquinolone ear drops is not very common, and they can be used in patients with tympanic membrane perforations.[1][12][32]​​​ However, one retrospective cohort study found that the use of fluoroquinolone-containing ear drops to treat AOE is associated with a previously unreported increased risk of developing tympanic membrane perforation, although this has not yet changed clinical practice.[40]

In one randomized clinical study of patients with AOE, it was found that a combined ciprofloxacin/dexamethasone preparation resulted in less time to cure when compared with polymyxin B/neomycin/hydrocortisone otic suspension.[41] Another randomized clinical trial found ciprofloxacin/dexamethasone otic to be equal in effectiveness to topical neomycin/polymyxin B/hydrocortisone administered with systemic amoxicillin in the treatment of AOE.[42] These observations have produced a shift in treatment preference toward the newer fluoroquinolone-containing ear drops.[32] However, the older topical solutions are still very commonly used and may be more affordable.

Care should be exercised in patients who are known, or suspected, to have a tympanic membrane perforation, including a tympanostomy tube, to avoid ototoxic ear drops (those that contain aminoglycosides and alcohol).[1][12]​ In that situation, ofloxacin or ciprofloxacin/dexamethasone can be used.[1]

Symptoms of diffuse AOE should improve within 48-72 hours of starting topical therapy. For patients who fail to show a response within this time frame, reassessment is recommended to confirm the diagnosis of diffuse AOE and exclude other conditions. Reasons for lack of response to treatment for diffuse AOE include obstruction of the ear canal, poor adherence to treatment, incorrect diagnosis, and microbiologic factors. If any obstruction cannot be addressed with removal of debris and/or wick placement, then systemic antibiotics may be needed. A culture of the external auditory canal can identify fungi, resistant bacteria, or unusual causes of infection that would need targeted topical or systemic therapy.[1] Culture and sensitivity may help to guide antibiotic therapy in patients refractory to initial treatment. If symptoms persist despite initial treatment, then alternative diagnoses such as skin disorders, foreign bodies, perforated tympanic membrane, or middle ear disease should be considered.

Patients with other medical problems

Patients with diabetes, those who have received irradiation, or those who are immunocompromised (e.g., with HIV/AIDS, or patients receiving chemotherapy) are at higher risk for rapid escalation from mild to severe manifestations of AOE or for developing necrotizing otitis externa.[1][12]​​[43]​ Treatment approach in these patients is different and requires the use of systemic antibiotics in addition to the treatment outlined under the general approach above.[1][13]​ In addition, irrigation should not be used to remove debris from these patients' ear canals, as this may predispose the patients to necrotizing otitis externa.[1] Patients with concurrent middle ear disease, such as acute otitis media or a tympanic membrane perforation, may also require systemic antibiotics.[1]

Oral ciprofloxacin is an effective medication; however, it is not generally recommended in children.[13] In addition, in November 2018, the European Medicines Agency (EMA) completed a review of serious, disabling, and potentially irreversible adverse effects associated with systemic and inhaled fluoroquinolone antibiotics. These adverse effects include tendonitis, tendon rupture, arthralgia, neuropathies, and other musculoskeletal or nervous system effects. As a consequence of this review, the EMA now recommends that fluoroquinolone antibiotics be restricted for use in serious, life-threatening bacterial infections only. Furthermore, they recommend that fluoroquinolones should not be used for mild to moderate infections, unless other appropriate antibiotics for the specific infection cannot be used, and should not be used in nonsevere, nonbacterial, or self-limiting infections. Patients who are older, have renal impairment, or have had a solid organ transplant, as well as those being treated with a corticosteroid, are at a higher risk of tendon damage. Coadministration of a fluoroquinolone and a corticosteroid should be avoided.[44] The UK-based Medicines and Healthcare products Regulatory Agency support these recommendations.[45] The Food and Drug Administration (FDA) issued a similar safety communication, restricting the use of fluoroquinolones in acute sinusitis, acute bronchitis, and uncomplicated urinary tract infections.[46] In addition to these restrictions, the FDA has issued warnings about the increased risk of aortic dissection, significant hypoglycemia, and mental health adverse effects in patients taking fluoroquinolones.[47][48]

Despite this, a systemic fluoroquinolone is usually required in patients with non-necrotizing otitis externa who have comorbidities (diabetes or immunocompromised state), as they are at higher risk for rapid escalation from mild to severe manifestations of AOE, or for developing necrotizing otitis externa.[1][12][43]​​​ Advice should be sought from an infectious diseases specialist to guide selenecrotizingction of antibiotic and decide on whether a fluoroquinolone is warranted here. In these patients, cultures may be taken to assist in the proper choice of oral antibiotics. Oral amoxicillin/clavulanate or amoxicillin are other options to cover Staphylococcus aureus if Pseudomonas aeruginosa is unlikely, or while awaiting results, or if cultures are negative. 

Necrotizing otitis externa

Necrotizing otitis externa is an aggressive infection that mainly affects older people with diabetes or those who are immunocompromised, and is a medical emergency.[7]​ Pseudomonas aeruginosa is implicated in most patients.[1][7]​ Staphylococci may also be implicated, including methicillin-resistant Staphylococcus aureus.[1] There are no unified guidelines for the management of necrotizing otitis externa. Some clinicians advocate starting intravenous antibiotics immediately, while others start a trial of oral ciprofloxacin in patients who are suspected to have necrotizing otitis externa not complicated by cranial nerve involvement.[49] Patients who do not respond to oral antibiotics within 24-48 hours should then be started on intravenous antibiotics. The author's usual practice is to try oral ciprofloxacin in early uncomplicated or suspected necrotizing otitis externa and assess the patient's response in 24-48 hours.

All patients in this group should have debridement of granulation tissue. Oral fluoroquinolones are active against Pseudomonas aeruginosa, penetrate the bone well, have excellent oral bioavailability, and have a less significant side effect profile compared with alternatives.[50] Oral ciprofloxacin has good coverage against Pseudomonas aeruginosa and is very commonly and successfully used in these patients. Patients can be given oral ciprofloxacin for 6-8 weeks.[51]

Resistance to ciprofloxacin has been reported, but multidrug resistance is rare.[7]​ If patients fail to respond to oral ciprofloxacin within 24-48 hours, they should be started on intravenous antibiotics that have antipseudomonal activity until culture and sensitivity results are obtained. Empirical intravenous antibiotics should be started based on the recommendation of the local infectious disease specialist. There is no standard recommendation, and the literature reports use of a wide range of antibiotics both singularly and in combination, including third- and fourth-generation cephalosporins (ceftazidime, cefepime), semi-synthetic penicillins (piperacillin), carbapenems (imipenem/cilastatin), aztreonam, and aminoglycosides (amikacin, tobramycin).[52][53]​ One retrospective case series and systematic literature review concluded that ceftazidime monotherapy for 6-7 weeks was effective for treating necrotizing otitis externa.[7]​ In the absence of specialist infectious disease advice, the author considers ceftazidime a reasonable first choice, with the others as alternative options.

Hyperbaric oxygenation can be used in patients with refractory or recurrent disease, or in patients with extensive skull base or intracranial involvement.[52][54]​ However, one systematic review about the use of hyperbaric oxygen as an adjuvant treatment for necrotizing otitis externa failed to show clear evidence demonstrating its efficacy when compared with treatment with antibiotics and/or surgery.[55]

Fungal

Acute fungal otitis externa is more common in tropical countries, humid locations, after long-term topical antibiotic therapy, and in people with diabetes, HIV/AIDS, or other immunocompromised states.[1] The most common fungal pathogens are Aspergillus species (60% to 90%) and Candida species (10% to 40%).[1]

The first line of treatment of fungal otitis externa is still in debate.[3] Acidifying agents such as acetic acid or aluminum acetate can be used.[12][56]​​​​ Patients who do not respond to treatment with acidifying agents can be started on antifungal topical treatment. If Candida is cultured, an oral antifungal (e.g., fluconazole, itraconazole) may help.[13][57]​​​ Further studies are needed to assess the benefit of oral antifungal agents in otomycosis.[57] Frequent cleaning and debridement by medical professionals is also an essential part of treatment. AOE secondary to Aspergillus infections may require the use of oral itraconazole.[16] If fungal otitis externa is refractory to treatment and there is progression of disease, consider fungal necrotizing otitis externa.[58] Topical antibiotic treatment, which is indicated in bacterial AOE, is contraindicated in fungal otitis externa because it is ineffective and may lead to further growth of fungi.[1]

Care should be exercised in patients who are known, or suspected, to have a tympanic membrane perforation, including a tympanostomy tube, to avoid ototoxic ear drops.[1][12]​​​​ Alcoholic solvents used to dissolve water-insoluble antifungal agents (e.g., clotrimazole) can also cause a burning or stinging sensation in the ear and may be ototoxic to the cochlea.​​[10] To overcome this, a wick saturated with the antifungal can be inserted in the ear canal to prevent the seepage of the irritant into the middle ear. Self-medication of clotrimazole solution with Q-tips has been shown to improve patient satisfaction and reduce recurrence.[59]​ One study evaluating paper patches in tympanic membrane perforation found that closing the perforation with a patch and applying Castellani’s solution topically was safe and effective, and a faster resolution of otomycosis was observed, accompanied by reduced recurrence.[60]

Severe swelling of the ear canal

Patients who have severe swelling of the ear canal may have difficulty using the ear drops. A wick should be inserted in the ear canal to allow for drug delivery. Such wicks are often made of dry, compressed Merocel® in a form that facilitates insertion into the swollen ear canal. Subsequent application of topical antibiotic solution expands the wick to fill the canal and make contact with the swollen tissue, thus enhancing penetration of the medication to the inflamed tissue. The wick can then either be removed or replaced after 48 hours if swelling persists. One study of three different packing materials in the treatment of severe AOE found that ear wick and ribbon gauze were superior to biodegradable synthetic polyurethane foam for relieving signs and symptoms, especially on the third day of treatment.[61] In some patients, cleaning of debris and/or placement of a wick may not be possible; these patients may require systemic antibiotics.[1]

Analgesics

Analgesics increase patient satisfaction and allow faster return to normal activities. Mild to moderate pain is usually controlled by acetaminophen or a nonsteroidal anti-inflammatory drug given alone or in combination with an opioid.[1] Analgesics should be started at the initial recommended dose and adjusted accordingly. Codeine is contraindicated in children younger than 12 years, and it is not recommended in adolescents ages 12-18 years who are obese or have conditions such as obstructive sleep apnea or severe lung disease as it may increase the risk of breathing problems.[62] It is generally recommended only for the treatment of acute moderate pain, which cannot be successfully managed with other analgesics, in children ages 12 years and older. It should be used at the lowest effective dose for the shortest period and treatment limited to 3 days.[63][64]

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