- Leigh Sanyaolu, ear, nose, and throat core surgical trainee,
- Sarah Farmer, ear, nose, and throat specialist registrar,
- Ali Raza, ear, nose, and throat consultant
- Correspondence to: L Sanyaolu lnsanyaolu{at}doctors.org.uk
A 48 year old man presented to the accident department with a three day history of right ear pain, yellow ear discharge, and mild hearing loss. He had seen his general practitioner two days before and had been prescribed oral antibiotics (amoxicillin 500 mg three times a day) and analgesia. However, over the past 24 hours the pain had got much worse and he was feeling generally unwell. His right pinna and surrounding skin had become red and tender.
He had no relevant medical history, was taking no regular drugs, and had no known allergies.
His right pinna was erythematous, with oedema visible at the external auditory meatus and concha. There was discharge in the intertragal notch and crusted debris over the lobule. Some erythema extended into the neck, inferior to the pinna. He was afebrile and the tympanic membrane was partly visualised and appeared normal. The external auditory canal was about 80% stenosed and there was discharge within the canal. He had no signs of meningism, no evidence of mastoiditis, and no cervical lymphadenopathy. Blood tests showed a white cell count of 12×109/L (reference range 4-11×109) and a C reactive protein of 100 mg/L (<5 mg/L; 1 mg/L=9.52 nmol/L).
Questions
1 On the basis of the history and examination findings, what is the likely diagnosis?
2 What are the common predisposing risk factors for this condition?
3 What are the most common causative organisms?
4 How is this condition managed?
Answers
1 On the basis of the history and examination findings, what is the likely diagnosis?
Short answer
This patient has right otitis externa with cellulitis of the pinna and surrounding soft tissue.
Long answer
Our patient has cellulitis of the right pinna and surrounding skin secondary to otitis externa (fig 1⇓). His condition probably started with inflammation and oedema of the external auditory canal and progressed to infection of the pinna and surrounding skin.
Fig 1 Clinical photograph showing oedema of the pinna (A), oedema of the external auditory canal (B), evidence of ear discharge (C), and cellulitis surrounding the pinna (D)
Acute otitis externa is defined as acute inflammation of the external auditory canal, usually secondary to bacterial infection.1 It is a common condition, especially in primary care, with a prevalence in the United Kingdom of more than 1%.1 The symptoms and signs of this condition include otalgia, pruritis, otorrhoea, and hearing loss, as well as erythema and oedema of the external auditory canal.1 2 Acute otitis externa usually starts with minimal otorrhoea, pruritis, and mild otalgia.2 It may then progress to the moderate stage with oedema and erythema of the external auditory canal, increasing pain, and increasing otorrhoea.2 In the severe stage, severe narrowing of the external auditory canal causes cellulitis of the pinna, severe pain, and systemic symptoms such as fever and malaise.2
2 What are the common predisposing risk factors for this condition?
Short answer
Risk factors for this condition include dermatological conditions such as eczema and psoriasis; trauma, particularly scratching and use of, or abrasion by, cotton buds; a compromised immune system; diabetes; foreign bodies or hearing aids; and environmental factors, such as humidity and water in the ear canal.
Long answer
An important part of the clinical history involves assessment of risk factors for acute otitis externa (box).1 2
Risk factors for acute otitis externa
Trauma
Scratching, cotton buds, abrasion
Environmental
Humidity, swimming
Dermatological
Eczema, psoriasis
Medical
Immunosuppression, diabetes
Other
Hearing aids, foreign bodies
3 What are the most common causative organisms?
Short answer
The most common causative organisms are Pseudomonas aeruginosa and Staphylococcus aureus. Less common causes include coliforms, fungal infections, and rarely viral infection.
Long answer
The pathogenic mechanisms vary, but the most common causative organism is P aeruginosa, which causes about 40% of cases.3 4 5 The next most common pathogens are Staphylococcus spp, mainly S aureus.3 4 5 Less common causative organisms include Gram negative bacteria and funguses such as candida.3 4 5
4 How is this condition managed?
Short answer
General treatment measures in adults include analgesia; strict water precautions (avoidance of water and use of ear plugs); and topical antimicrobial ear drops, such as a fluoroquinolone (eye drops) or aminoglycoside (with or without steroid). Aural toilet is important. Wick insertion may be needed in cases of oedema of the ear canal, and patients may require admission for intravenous antibiotics (flucloxacillin) to treat cellulitis of the pinna and surrounding skin.
Long answer
Most cases of acute otitis externa can be managed in primary care, with analgesia, advice on ear care, and topical treatment being the mainstay of management. Analgesia is important because this condition is often painful. Another key aspect of management is to stress the importance of strict water precautions, because failure to avoid water will lead to unsuccessful treatment or progression of the condition. We recommend advising patients to use cotton wool smeared with Vaseline when bathing or showering. Swimming should be avoided, and those who use hearing aids should be advised to keep the aids out of the affected ear as much as possible.
The main reason for referral to secondary care is difficulty in administering topical treatment, either because of severe otorrhoea or obstruction secondary to oedema of the external auditory canal. When otorrhoea is severe, aural toileting is important not only for symptom control but also to make the administration of topical treatment easier. When the external auditory canal is oedematous and stenosed by 50% or more, a wick is inserted to allow topical treatment to reach the medial part of the ear canal.2 5 The wick will need to be removed within two or three days of insertion and the ear reassessed.
Topical treatment is the mainstay of treatment for uncomplicated acute otitis externa in adults. An ear swab should be taken before starting treatment to isolate causative organisms. However, the best topical treatment to use is unclear. Antimicrobial ear drops combined with steroid have been shown to improve the treatment of uncomplicated acute otitis externa.4 6 Acetic acid with steroid has been shown to be as effective as antibiotic drops with steroid, and is an alternative treatment option.4 6 Antibiotics used are usually an aminoglycoside (gentamicin, neomycin), with or without a steroid, or a fluoroquinolone such as ofloxacin (no steroid preparation available).4 In the UK, fluoroquinolones are available only as eye drops and are not licensed for use within the ear; however, these drops are commonly used to treat acute otitis externa. If the tympanic membrane is perforated or poor views make it difficult to assess, aminoglycosides should be avoided because of the risk of ototoxicity.2 The use of systemic antibiotics is reserved for disease that extends beyond the ear canal, patients who do not improve with oral antibiotics, and immunocompromised patients.1 5 The choice of antibiotic should be based on ear swabs and advice from the microbiology department.
Patient outcome
Our patient was admitted to hospital for pain control and spreading cellulitis despite oral antibiotics. He was treated with analgesia, daily aural toileting, and wick insertion for the first four days. Topical gentamicin combined with steroid ear drops (Gentisone HC; two drops three times a day) and intravenous flucloxacillin 1 g four times a day were used to treat the pinna cellulitis. Ear swab results showed heavy growth of Pseudomonas spp. After 72 hours of treatment his symptoms improved, so he was discharged and advised to complete a one week course of oral flucloxacillin together with gentamicin and steroid ear drops. At follow-up in the ear, nose, and throat emergency clinic four days later his symptoms had almost completely resolved. He was therefore discharged from the clinic.
Notes
Cite this as: BMJ 2013;346:f1739
Footnotes
Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Provenance and peer review: Not commissioned; externally peer reviewed.
Patient consent obtained.