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Practice Rational Testing

Ordering and interpreting ear swabs in otitis externa

BMJ 2014; 349 doi: (Published 01 September 2014) Cite this as: BMJ 2014;349:g5259

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We agree with Pankhania that the prevalence of ototoxicity from aminoglycoside antibiotics has been overestimated.1 Nevertheless, systemic aminoglycosides can clearly be ototoxic and estimates of prevalence of associated ear damage depend on the intensity of monitoring and the number of aminoglycoside courses: 24% of children with cystic fibrosis who received several courses of intravascular aminoglycosides had evidence of ear damage.2 There are few data on the incidence and prevalence of ototoxicity from topical aminoglycosides to treat otitis externa in people with a perforated eardrum.1 Routine use of a single course of aminoglycoside-containing ear drops for less than one week does not appear to cause clinically evident cochlear damage.3 However, a recent, large population-based study to evaluate the comparative safety of two commonly prescribed eardrop preparations in patients with non-intact tympanic membranes found 3.3 new cases of sensorineural hearing loss per 1,000 children treated with two or more courses of neomycin eardrop compared to fluoroquinolone users.4 Ototoxicity might be underreported when hearing loss alone is considered, since vestibular function is more prone to aminoglycoside-related damage compared to hearing function, and few studies have evaluated vestibular function.1 Further high-quality research about the potential ototoxicity of topical aminoglycosides is therefore needed.

US guidelines state that aminoglycoside containing drops are contraindicated when the eardrum is perforated and recommend quinolone eardrops (not licensed in the UK for this indication) under these circumstances.5 Similarly, the British National Formulary continues to state that topical aminoglycosides or polymyxins are contraindicated in patients with a perforated tympanic membrane or patent grommets. However, the BNF does note that these drops may be used cautiously by specialists for patients with chronic suppurative otitis media.6

Pankhania also recommends eardrops as first-line treatment and oral antibiotic treatment in complicated otitis externa. Our recommendation was in clear agreement with this view.

1. Phillips JS, Yung MW, Burton MJ, Swan IRC. Evidence review and ENT-UK consensus report for the use of aminoglycoside-containing ear drops in the presence of an open middle ear. Clin Otolaryngol 2007;32:330-6.
2. Al-Malky G, Dawson SJ, Sirimanna T, Bagkeris E, Suri R. High-frequency audiometry reveals high prevalence of aminoglycoside ototoxicity in children with cystic fibrosis. J Cyst Fibros 2014 Aug 12. pii: S1569-1993(14)00170-2.
3. Haynes DS, Rutka J, Hawke M, Roland PS. Ototoxicity of ototopical drops--an update. Otolaryngol Clin North Am 2007;40:669-83.
4. Winterstein AG, Liu W, Xu D, Antonelli PJ. Sensorineural hearing loss associated with neomycin eardrops and nonintact tympanic membranes. Otolaryngol Head Neck Surg 2013;148:277-83.
5. Rosenfeld RM, Schwartz SR, Cannon CR, Roland PS, Simon GR, Kumar KA, et al. Clinical practice guideline: acute otitis externa. Otolaryngol Head Neck Surg 2014;150(1 Suppl):S1-S24.
6. The British National Formulary, 2014. British National Formulary; British Medical Association and Royal Pharmaceutical Society of Great Britain, London. Available at:

Competing interests: CL has received research grants from the European Commission (Sixth and Seventh Programme Frameworks), Catalan Society of Family Medicine, and Instituto de Salud Carlos III. CCB is also Director of the Welsh Government funded Wales School of Primary Care Research, has received grants from several publicly funded research granted bodies, and honoraria for participation in workshops.

30 September 2014
Carl Llor
Senior visiting research fellow
Christopher C Butler. Professor of primary care, Department of Primary Care Health Sciences Oxford University, New Radcliffe House, Radcliffe Observatory Quarter, Woodstock Road. Oxford OX2 6NW, and Professor of Primary Care Medicine, Institute of Primary Care and Public Health. School of Medicine, Cardiff University
Institute of Primary Care and Public Health. School of Medicine, Cardiff University
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