ENT consultant Dr Richard Morgan offers his hints on managing this persistent and troublesome primary care problem
1. It's important to distinguish acute otitis externa from otitis media and other causes of the draining ear.
Acute otitis media sometimes needs to be treated systemically, but otitis externa rarely does. The characteristics of acute otitis externa are:
• rapid onset – usually within 48 hours – plus
• symptoms of ear canal inflammation, including often severe pain, itching or fullness, possibly with hearing loss or jaw pain plus
• signs of ear canal inflammation, including tenderness of the tragus, pinna (or both) or diffuse ear canal oedema or erythema (or both).
2. It's very likely to be a bacterial infection, but don't assume it is.
Well over 90% of otitis externa is bacterial, usually Pseudomonas aeruginosa or Staphylococcus aureus. When the infection is localised, it could be due to an infected hair follicle. More general infections of the outer ear can be bacterial or fungal, though fungal infections are much rarer and usually occur after prolonged antibiotic courses, with or without steroids.1
3. Aetiology may well be infectious – but also consider inflammatory conditions, allergies or irritants.
Skin diseases which may be involved include acne, psoriasis, seborrhoeic dermatitis, atopic eczema or systemic lupus erythematosus. Irritants include topical medications, earplugs or hearing aids. Consider the possibility of ear trauma from foreign bodies, damage caused by overzealous use of cotton buds or over-aggressive ear syringing.
4. Malignant otitis externa is rare, but you need to be able to spot it.
Patients are typically elderly and diabetic with severe, unremitting otalgia, aural fullness, otorrhoea and hearing loss.2 The hearing loss is conductive. Headache, jaw pain and reduced oral intake because of an inability to fully open the mouth may be present. Purulent otorrhoea and a swollen, painful external auditory canal are classic symptoms on examination. Another classic sign is exposed bone or granulation tissue on the floor of the canal. Consider it in any immunocompromised patient with external otitis and severe pain – especially if they have diabetes.
5. Topical treatments used alone will be effective for the vast majority of patients with uncomplicated acute otitis externa.
Many patients treated in A&E and primary care are still prescribed systemic antibiotics, despite evidence that many otitis externa pathogens will not respond. A recent Cochrane review suggested the choice of topical treatment doesn't appear to influence the outcome significantly.3 Acetic acid was effective and comparable to an antibiotic/ steroid combination at week one, but when treatment needed to be longer it was less effective. There is very little evidence to support the use of steroid-only drops.
6. The usual seven to 10-day course of treatment will under-treat some patients and over-treat others.
It might be more useful to tell patients to use the drops for at least a week and if they still have symptoms to carry on using the drops until symptoms resolve, up to a further seven days. If symptoms last beyond two weeks it is classified as a treatment failure.
7. If you decide to treat but have an element of doubt about the diagnosis, make sure you follow up.
In many cases, you can make the diagnosis with confidence – but if not, and you prescribe an antibiotic, make sure you take a look at the ear drum at a follow-up appointment. Refer if you can't visualise the ear drum because of discharge.
8. Don't forget analgesia and try to match the analgesic to pain severity.
Mild to moderate pain usually responds well to paracetemol or an NSAID with or without an opioid such as codeine. Opioids such as fentanyl may be needed for procedure-related pain and moderate to severe, round-the-clock pain.
9. Don't assume topical antibiotics will be used correctly.
There is evidence that up to 60% of people self-administering ear drops don't do it properly. The drops should be warmed up first by holding the bottle for a few minutes. The patient should lie down, affected ear uppermost, and the ear should be filled with drops and left for at least three minutes and up to five. If a child – or for whatever reason an adult – can't lie down that long, a small piece of cotton wool covered in Vaseline can be used to plug the external opening of the ear canal.
10. It's worth emphasising how patients can stop the condition re-occurring.
Recommendations to prevent acute otitis externa are aimed at keeping the ear canal dry. Removing any lumps of cerumen that could cause an obstruction would reduce the chances of getting another infection. But remove too much and its role as a barrier to moisture and infection is lost.
Dr Richard Morgan is an ENT consultant for the Cwm Taf Health Board in Cardiff
Competing interests None declared
Otitis externa Otitis externa
