Acute otitis externa in children

Abstract

Question In the summer months I see many children with uncomplicated acute otitis externa (AOE). I am aware of the multiple ototopical preparations. Which is the best first-line agent to treat AOE, and is there a role for an oral antibiotic?

Answer There are no specific Canadian guidelines for the management of AOE. However, current American guidelines promote initial ototopical therapy without systemic antibiotics for uncomplicated AOE; suggest there is little difference between the various ototopical preparations; and recommend the choice of treatment be based on the specific clinical situation. In practice, this often results in prescribing an antibiotic-steroid formulation for 7 to 10 days. This ototopical treatment option is supported by a recent Cochrane review that has documented the superiority of an antibiotic-steroid combination when compared with placebo or acetic acid in providing clinical resolution of AOE.

Acute otitis externa (AOE) is a common condition in the pediatric population characterized by diffuse inflammation of the external acoustic meatus.¹ The 2003 to 2007 data from the Centers for Disease Control and Prevention estimate a yearly incidence of 8.1 per 1000 population, with a higher incidence during the summer months in children between the ages of 5 and 14 years old.²

Acute otitis externa is colloquially known as swimmer’s ear for its preponderance in children who have a history of prolonged water exposure.³ Other predisposing factors include humidity, maceration, local trauma, external devices, dermatitides, anatomic abnormalities, and canal obstruction, which might make the canal epithelium susceptible to infections.⁴

Diagnosis of AOE

A diagnosis of AOE requires a rapid onset (within 48 hours) of signs and symptoms of external acoustic meatus inflammation with or without infection.⁵ Typical symptoms include otalgia, itching, and aural fullness. Signs include tenderness of the tragus and pinna, diffuse ear canal edema, conductive hearing loss, erythema, and otorrhea.⁵ Acute otitis externa must be distinguished from other causes of external ear pain including furunculosis, herpes zoster oticus, otomycosis, chronic otitis externa, malignant otitis externa, acute otitis media with perforation, contact dermatitis, and retained foreign body, as these will all have varying treatments.⁴

Overall, 90% of AOE cases are unilateral,¹ and in North America more than 90% of the time AOE is caused by bacterial infection, with a low incidence of fungal infection.⁶ Pseudomonas aeruginosa and Staphylococcus aureus are the most common pathogens responsible for AOE, with Staphylococcus spp being less prevalent in children than in adults.⁶

Rationale for treatment

A 2012 prospective observational study of 106 patients who presented to an ears, nose, and throat emergency clinic in the United Kingdom reported that 42% of the patients had not received treatment before arrival, 14% received topical antibiotics alone, and 44% received oral antibiotics either alone or with topical treatment.⁷ Although none of the patients was younger than 18 years of age, this research highlights the variation in how AOE is treated. All patients eventually received ototopical antibiotics from the clinic.⁷

Local treatment with antibiotic ear drops is the initial treatment of choice because it creates antibiotic concentrations 100-fold to 1000-fold higher⁵ than systemic therapy, and has the advantage of not causing systemic side effects or promoting resistance.⁶ Topical aminoglycosides (neomycin, gentamicin) and fluoroquinolones (ciprofloxacin, ofloxacin) are efficacious against bacteria that cause AOE.^5,6 However, if there is a proven or suspected perforation of the tympanic membrane, then aminoglycosides are contraindicated owing to their ototoxic properties.⁸

The addition of steroids to reduce inflammation of the external acoustic meatus or the addition of acetic acid to reduce the pH of the ear canal is also common practice.⁹ The rationale for use of acetic acid is to return the pH to an acidic and more antimicrobial environment.⁸ There is anecdotal evidence that avoidance of swimming while healing is beneficial, and inciting factors such as the use of cotton buds should be discouraged.^4,9

In children with edematous ear canals, drops cannot penetrate the entire length of the canal and an ear wick can be used as a conduit.¹⁰ In addition, the need for oral analgesia should be assessed, as this is often required before ototopical treatment takes effect.⁵

Treatment guidelines

In 2006 the American Academy of Otolaryngology— Head and Neck Surgery Foundation published a clinical guideline supporting the use of topical antimicrobials as first-line treatment in otherwise healthy patients with AOE.⁵ A meta-analysis of 2 trials that compared topical antimicrobials with placebo reported an absolute rate difference of 0.46 (95% CI 0.29 to 0.63, number needed to treat = 2), supporting antimicrobials over placebo.⁵ Meta-analyses of different topical antimicrobials showed no significant differences in clinical cure rates and demonstrated that regardless of which topical agent was used, 65% to 90% of patients had clinical resolution within 7 to 10 days.⁵ In a study of 842 patients with AOE between the ages of 2 and 85, Pistorius et al demonstrated that the addition of steroids to ciprofloxacin resulted in a reduction of 0.88 days in the duration of ear pain (P = .039),¹¹ which might be clinically significant for many children.

Initial therapy of diffuse uncomplicated AOE should include a topical antimicrobial agent, and there is consensus that adding a systemic antibiotic is unlikely to be beneficial.⁹ This is supported by a double-blind trial¹² of 100 patients randomized to receive topical and oral antibiotics or topical antibiotics with placebo that reported no significant changes in severity, duration, or cure rates of AOE in the primary care setting (P > .4, P > .5, P > .8, respectively). The role of systemic antibiotics is in treating patients with AOE complicated by immunosuppression or by infections outside the ear canal, such as cellulitis, osteitis, abscess formation, necrotizing otitis externa, and mastoiditis.^5,13

Ototopical treatment with an antibiotic-steroid combination was significantly more effective than placebo drops (odds ratio [OR] 11, 95% CI 2.00 to 60.57) based on data from a double-blind trial¹⁴ of 40 patients aged 2 to 68 years old used in a Cochrane review from 2010.¹⁵ In a 3-armed randomized controlled trial of 213 adults in the primary care setting, van Balen and colleagues compared topical treatments containing acetic acid, acetic acid and steroid, and antibiotic and steroid.¹⁶ They demonstrated that acetic acid was less effective than antibiotic-steroid drops at 2 weeks (OR 0.29, 95% CI 0.13 to 0.62) and 3 weeks (OR 0.25, 95% CI 0.11 to 0.58), with a median recovery in the antibiotic-steroid group of 6 days (95% CI 5.1 to 6.9 days) compared with 8 days (95% CI 7.0 to 9.0 days) in the acetic acid group.^15,16 The Cochrane review reported no clinically meaningful differences in clinical resolution of AOE when comparing various ototopical antimicrobials but insists they are effective with or without steroids, with cure rates of 55% to 100% as compared with 10% for placebo drops.¹⁵ There were no significant differences found when comparing quinolone versus nonquinolone ototopical antibiotics, and ciprofloxacin was not inferior to previously used aminoglycosides.^15,17 As the clinical trials identified no relevant clinical differences, other factors such as ototoxicity, contact sensitivity, antibiotic resistance, availability, cost, and dosing schedule need to be considered when selecting ototopical antimicrobial treatment.^5,15

Conclusion

Ototopical antimicrobials are effective in the treatment of AOE regardless of which preparation is used, and it is not necessary to prescribe an oral antibiotic unless there is infection outside the external ear canal. It is advisable to use an antibiotic-steroid formulation for 7 to 10 days, as it has been shown to be superior to placebo or acetic acid in providing clinical resolution of uncomplicated AOE. The choice of antibiotic remains dependent on the clinical scenario. In the specific setting of a disrupted tympanic membrane, fluoroquinolones are indicated given the potential ototoxicity of aminoglycosides.

PRETx

Child Health Update is produced by the Pediatric Research in Emergency Therapeutics (PRETx) program (www.pretx.org) at the BC Children’s Hospital in Vancouver, BC. Mr McWilliams and Dr Smith are members and Dr Goldman is Director of the PRETx program. The mission of the PRETx program is to promote child health through evidence-based research in therapeutics in pediatric emergency medicine.

Do you have questions about the effects of drugs, chemicals, radiation, or infections in children? We invite you to submit them to the PRETx program by fax at 604 875–2414; they will be addressed in future Child Health Updates. Published Child Health Updates are available on the Canadian Family Physician website (www.cfp.ca).