Acute Otitis Media

Acute otitis media is one of the most common infections in childhood. It is the leading reason for antibiotic prescribing in children under five globally, yet the evidence base for routine antibiotic treatment is less clear-cut than prescribing patterns suggest. Understanding the condition well — its pathophysiology, the organisms responsible, the factors that determine who actually needs antibiotics, and the distinction between AOM and the much more common otitis media with effusion — is essential for every clinician who sees children.

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Pathophysiology — Why the Middle Ear Gets Infected

The middle ear cleft communicates with the nasopharynx via the Eustachian tube — a mucosal-lined canal that serves as the pressure equalisation, drainage, and mucociliary clearance pathway for the middle ear. In adults, the Eustachian tube runs at approximately 45° to the horizontal, and its cartilaginous support helps maintain patency. In children under two years, the tube is shorter, more horizontal (approximately 10° from horizontal), and functionally more compliant — it opens poorly on swallowing and closes poorly against positive nasopharyngeal pressure. These anatomical differences explain why AOM is predominantly a disease of early childhood.

The sequence of events in most AOM:

1. An upper respiratory tract infection (viral in origin) causes Eustachian tube mucosal oedema and dysfunction
2. Normal drainage and pressure equalisation fail — negative pressure develops in the middle ear
3. Nasopharyngeal secretions, carrying bacteria, are aspirated into the middle ear
4. A middle ear effusion forms, initially sterile, then infected
5. The inflammatory response produces the classic presentation

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AOM vs Otitis Media with Effusion (OME)

This distinction is examined constantly and confused constantly. They represent different points on a spectrum of middle ear disease.

Acute otitis media is an acute infection of the middle ear with signs of acute inflammation — a bulging, erythematous tympanic membrane; fever; severe otalgia. The middle ear contains pus or infected fluid under pressure.

Otitis media with effusion (OME, “glue ear”) is the presence of fluid in the middle ear without signs of acute infection — no fever, no otalgia, no erythema, no bulging. The membrane appears dull, retracted, or amber-tinged, with impaired or absent mobility. The child has hearing loss (typically mild to moderate conductive) but is not acutely unwell.

OME is extremely common in children — estimates suggest 80% of children have at least one episode before school age. Most resolve spontaneously within three months. It becomes a management issue when it persists (>3 months) and causes significant hearing loss affecting speech and language development.

The two conditions are related: most AOM episodes leave a residual middle ear effusion (OME) for several weeks. The effusion resolves in the majority. Recurrent AOM, or persistent OME with hearing loss, is the indication for grommet insertion.

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Organisms

The three most common bacterial pathogens in AOM are:

Streptococcus pneumoniae — responsible for approximately 35-40% of bacterial AOM. Tends to produce the most severe presentations with higher fever and more intense otalgia. Most cases are amenable to amoxicillin, though beta-lactam resistance is an increasing concern in some populations.

Haemophilus influenzae (non-typeable) — approximately 25-30%. Less severe than pneumococcal AOM on average. A significant proportion (30-40%) are beta-lactamase-producing and therefore amoxicillin-resistant; these require co-amoxiclav.

Moraxella catarrhalis — approximately 10-15%. High rate of beta-lactamase production. However, Moraxella AOM has a high rate of spontaneous resolution and may not require antibiotics.

In practice, microbiological diagnosis is almost never made in typical outpatient AOM — the choice of antibiotic is empirical, targeting all three organisms.

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Presentation

Otalgia is the dominant symptom. It is typically sudden in onset, often nocturnal (lying down impairs Eustachian tube drainage and increases middle ear pressure), and can be severe enough to wake the child from sleep. Infants too young to localise pain present with ear-pulling, irritability, disturbed sleep, and inconsolable crying.

Fever — present in most children with bacterial AOM, though the degree varies. Temperatures above 39°C are more common with pneumococcal aetiology.

Hearing loss — the effusion in the middle ear produces a mild to moderate conductive hearing loss. Parents may notice the child not responding to speech or turning up the television volume. In a single unilateral episode, this is rarely significant; in recurrent AOM or persistent effusion, the cumulative hearing impairment matters.

Otorrhoea — if the tympanic membrane perforates spontaneously (which it does in a proportion of cases), mucopurulent discharge appears in the canal. The otalgia typically resolves dramatically at the moment of perforation, which is physiological pressure relief. The perforation usually heals within a few weeks.

Preceding URTI — the majority of AOM episodes follow by a few days the onset of a viral upper respiratory infection. The temporal association is important both diagnostically and for parental counselling.

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Examination

Otoscopy is the key examination. Several findings are diagnostic of AOM:

Bulging tympanic membrane — the single most important sign. Pus under pressure pushes the membrane outward, producing a convex, sometimes almost spherical appearance in severe cases. This finding alone, in the context of the history, establishes the diagnosis.

Erythema — the membrane appears red. Important caveat: erythema alone is not diagnostic and can be caused by fever, crying, or any vascular engorgement. A pink-tinged membrane in an afebrile child without bulging is not AOM.

Loss of landmarks — the normal tympanic membrane has visible landmarks (light reflex, handle of malleus, long process of incus). Oedema, opacity, or bulging obscures these.

Reduced or absent light reflex — the cone of light (normally at the five o’clock position in the right ear) is distorted or absent.

Opacity — a white, yellow, or amber membrane indicates fluid or pus in the middle ear. This can also be seen in OME.

In infants and young children, otoscopy requires adequate restraint, an appropriate speculum size, and a gentle technique. Canal oedema from crying, wax occlusion, and cerumen all complicate examination. A video otoscope improves the documentation and clinical confidence of findings significantly.

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Tympanometry

Tympanometry measures the compliance (mobility) of the tympanic membrane as a function of ear canal air pressure. It is an objective test that does not require patient cooperation beyond remaining still for a few seconds.

Type A tympanogram: Normal. Peak compliance at atmospheric pressure. Normal middle ear.

Type B tympanogram: Flat curve — no compliance peak. Indicates fluid in the middle ear (AOM, OME), tympanic membrane perforation (with a large ear canal volume on the same trace), or wax impaction. In the context of AOM, a Type B tympanogram confirms effusion.

Type C tympanogram: Compliance peak at negative pressure. Indicates Eustachian tube dysfunction with negative middle ear pressure — often a precursor state to AOM or OME.

Tympanometry is particularly useful in children where otoscopy is difficult, in confirming OME, and in monitoring response to treatment.

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Management

Analgesia First — Always

Regardless of antibiotic decision, adequate pain relief is the immediate priority. Paracetamol and ibuprofen are both effective for AOM-related otalgia in children. Topical anaesthetic ear drops can supplement systemic analgesia but have limited evidence for middle ear pain (they help external canal discomfort).

Watchful Waiting vs Antibiotics

flowchart TD
    A["Diagnosed AOM — analgesia for ALL"] --> B{"Any mandatory-antibiotic criterion?"}
    B -->|Yes| C["Antibiotics now: high-dose amoxicillin"]
    B -->|No| D["Watchful waiting 48-72h, with safety-net prescription"]
    D -->|"Not improving by 48-72h"| C
    M["Mandatory: under 6 months · severe (fever ≥ 39°C or otalgia ≥ 48h) · bilateral under 2y · otorrhoea · immunocompromised"] -.-> B

The central management question. The Cochrane systematic review of antibiotics for AOM in children (Venekamp et al., 2015) found that most children with AOM recover without antibiotics within 2-3 days, with approximately 80% experiencing resolution with analgesic management alone. Antibiotics reduce pain at days 2-3 and reduce the risk of contralateral infection but also carry risks (diarrhoea, rash, contribution to antimicrobial resistance).

The American Academy of Pediatrics guidelines (Lieberthal et al., Pediatrics 2013) recommend antibiotics in the following situations:

Antibiotic mandatory:

• Children under 6 months
• Severe AOM (fever 39°C or higher, severe otalgia for 48 hours or more)
• Bilateral AOM in children under 2 years
• AOM with spontaneous tympanic membrane perforation (otorrhoea)
• Immunocompromised patients

Watchful waiting acceptable (with antibiotic prescription issued but deferred for 48-72 hours):

• Children 2 years and older with non-severe unilateral AOM
• Children 6-24 months with non-severe unilateral AOM in whom close follow-up can be assured

Antibiotic of choice: Amoxicillin (high dose — 80-90 mg/kg/day in divided doses) remains first-line for most uncomplicated AOM. Co-amoxiclav is used if there is no improvement after 48-72 hours of amoxicillin (suggesting beta-lactamase-producing H. influenzae or Moraxella), or in a child who has received amoxicillin within the past 30 days.

Recurrent AOM and Grommet Insertion

Recurrent AOM is defined as three or more episodes in six months, or four or more in twelve months with at least one in the preceding six months. Grommet (ventilation tube) insertion is the surgical management — a small tube is inserted through a myringotomy incision in the anteroinferior quadrant of the tympanic membrane, ventilating the middle ear and preventing the negative-pressure effusion that facilitates bacterial colonisation. Grommets typically remain in situ for 6-18 months before extruding spontaneously.

For OME with hearing loss persisting beyond three months, grommet insertion is indicated when the hearing loss is significant (typically 25-30 dB or more) and affecting speech, language, or educational development. Watchful waiting for three months from confirmed diagnosis is standard before surgery is considered.

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Complications

Complications of AOM are less common in the antibiotic era but remain important and are a standard MBBS examination topic.

Local complications:

• Tympanic membrane perforation — spontaneous, typically heals
• Acute mastoiditis — the most common intratemporal complication; erythema, oedema, and tenderness over the mastoid with forward displacement of the auricle; requires IV antibiotics and often cortical mastoidectomy
• Facial nerve palsy — from oedema in a dehiscent facial nerve canal
• Labyrinthitis — infection spreading to the inner ear

Intracranial complications — extradural abscess, meningitis, brain abscess, lateral sinus thrombophlebitis. These are less common from AOM than from CSOM but can occur in severe or inadequately treated disease. The pathways and presentations mirror those described in the CSOM complications article.

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Key Numbers

Parameter	Value
Peak age incidence	6-24 months
Spontaneous resolution without antibiotics	~80% within 2-3 days
Antibiotic NNT (prevent 1 extra day of pain)	~9
Recurrent AOM definition	3 or more episodes in 6 months, or 4 or more in 12 months
Grommet duration in situ	6-18 months
Most common bacterial pathogen	Streptococcus pneumoniae (~35-40%)
First-line antibiotic	Amoxicillin 80-90 mg/kg/day

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Frequently Asked Questions

Why do children get AOM so much more often than adults? The Eustachian tube in children is shorter, more horizontal, and functionally immature — it fails to open adequately on swallowing and provides poor drainage of the middle ear. This, combined with the frequency of viral upper respiratory infections in the first few years of life (6-8 per year), creates recurrent episodes of Eustachian tube dysfunction and middle ear effusion. As the skull grows and the tube lengthens and changes angle, the incidence falls sharply — most children grow out of recurrent AOM by school age.

Should I give ear drops in AOM? Topical antibiotic drops are not effective for uncomplicated AOM because an intact tympanic membrane prevents the drug from reaching the middle ear. They are appropriate when spontaneous perforation has occurred (otorrhoea is present) — in that setting, topical quinolone drops combined with systemic antibiotics are indicated. Do not use aminoglycoside drops (gentamicin, neomycin) if the drum is perforated or uncertain — these are potentially ototoxic via direct cochlear exposure.

Is there a role for decongestants or antihistamines in AOM? No good evidence supports their use. Systemic decongestants do not reliably improve Eustachian tube function in children with AOM, and antihistamines have no demonstrated benefit unless the child has concurrent allergic rhinitis contributing to Eustachian tube dysfunction. Prescribing them risks side effects without clinical benefit.

What is the Valsalva manoeuvre and does it help AOM? The Valsalva manoeuvre — forced exhalation against a closed glottis — transiently increases nasopharyngeal pressure and can open the Eustachian tube, equalising middle ear pressure. It is helpful for barotrauma-related ear fullness (in a swimmer or after flight) where negative pressure in the middle ear is the problem, but it is contraindicated in the context of active AOM — forcing infected nasopharyngeal content into the middle ear under positive pressure would worsen the infection.

My patient has AOM and a tympanic membrane perforation — do I still use amoxicillin? Yes, with the addition of topical antibiotic drops. Systemic amoxicillin addresses the middle ear infection. Topical quinolone drops (e.g. ciprofloxacin) treat the external canal contamination and provide local drug delivery through the perforation. Avoid aminoglycoside-containing drops when the drum is perforated. The perforation itself should be documented and followed up to confirm closure at 6-8 weeks.