Acute otitis media (AOM)


Acute inflammation of the middle ear, due to viral or bacterial infection, very common in children under 3 years, but uncommon in adults.
The principal causative organisms of bacterial otitis media are Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and in older children, Streptococcus pyogenes.

Clinical features

– Rapid onset of ear pain (in infants: crying, irritability, sleeplessness, reluctance to nurse) and ear discharge (otorrhoea) or fever.

– Other signs such as rhinorrhoea, cough, diarrhoea or vomiting are frequently associated, and may confuse the diagnosis, hence the necessity of examining the tympanic membranes.

– Otoscopy: bright red tympanic membrane (or yellowish if rupture is imminent) and presence of pus, either externalised (drainage in ear canal if the tympanic membrane is ruptured) or internalised (opaque or bulging tympanic membrane). The combination of these signs with ear pain or fever confirms the diagnosis of AOM.
Note:
The following otoscopic findings are not sufficient to make the diagnosis of AOM:
• A red tympanic membrane alone, with no evidence of bulging or perforation, is suggestive of viral otitis in a context of upper respiratory tract infection, or may be due to prolonged crying in children or high fever.
• The presence of air bubbles or fluid behind an intact tympanic membrane, in the absence of signs and symptoms of acute infection, is suggestive of otitis media with effusion (OME).

– Complications, particularly in high-risk children (malnutrition, immunodeficiency, ear malformation) include chronic suppurative otitis media, and rarely, mastoiditis, brain abscess or meningitis.

Treatment

– In all cases:
• Treatment of fever and pain: paracetamol PO (Chapter 1).
• Ear irrigation is contra-indicated if the tympanic membrane is ruptured, or when the tympanic membrane cannot be fully visualised. Ear drops are not indicated.

– Indications for antibiotic therapy:
• Antibiotics are prescribed in children less than 2 years, children whose assessment suggests severe infection (vomiting, fever > 39 °C, severe pain) and children at risk of unfavourable outcome (malnutrition, immunodeficiency, ear malformation).
• For other children:

  1. If the child can be re-examined within 48 to 72 hours: it is preferable to delay antibiotic prescription. Spontaneous resolution is probable and a short symptomatic treatment of fever and pain may be sufficient. Antibiotics are prescribed if there is no improvement or worsening of symptoms after 48 to 72 hours.
  2. If the child cannot be re-examined: antibiotics are prescribed.

• For children treated with antibiotics: advise the mother to bring the child back if fever and pain persist after 48 hours.

– Choice of antibiotherapy:

• Amoxicillin is the first-line treatment:
amoxicillin PO for 5 days
Children: 30 mg/kg 3 times daily (max. 3 g daily)
Adults: 1 g 3 times daily

• Amoxicillin/clavulanic acid is used as second-line treatment, in the case of treatment failure. Treatment failure is defined as persistence of fever and/or ear pain after 48 hours of antibiotic treatment.
amoxicillin/clavulanic acid (co-amoxiclav) PO for 5 days. Use formulations in a ratio of 8:1 or 7:1. The dose is expressed in amoxicillin:
Children < 40 kg: 25 mg/kg 2 times daily
Children ≥ 40 kg and adult:
Ratio 8:1: 2000 mg daily: 2 tablets of 500/62.5 mg 2 times daily
Ratio 7:1: 1750 mg daily: 1 tablet of 875/125 mg 2 times daily

Persistence of a ear drainage alone, without fever and pain, in a child who has otherwise improved (reduction in systemic symptoms and local inflammation) does not warrant a change in antibiotic therapy. Clean ear canal by gentle dry mopping until no more drainage is obtained.

• Macrolides should be reserved for very rare penicillin-allergic patients, as treatment failure (resistance to macrolides) is frequent.
azithromycin PO
Children over 6 months: 10 mg/kg once daily for 3 days