Malignant otitis externa

Background

• Otitis externa that is invasive into adjacent soft tissue and bone

Microbiology

• Pseudomonas aeruginosa (95%), which is never a colonizer in this context
• Staphylococcus aureus
• Aspergillus species, rarely

Risk Factors

• More common in patients with diabetes, immunocompromised patients, and frail elderly patients

Clinical Manifestations

• Severe pain and tenderness around the ear and mastoid process, plus purulent drainage from external ear canal
• May spread to involve temporal bone, sigmoid sinuses, skull base, jugular vein, meninges, and brain
• Can cause peripheral palsies of cranial nerves; most commonly VII, but also IX, X, and XII

Management

• Clean and debride the ear canal
• Systemic antibiotics as well as topical eardrops that include a corticosteroid
  • Should be antipseudomonal, unless otherwise directed by cultures
  • e.g. ceftazidime, cefepime, or piperacillin-tazobactam, with or without an adjunctive aminoglycoside
  • Use of external eardrops is debated
• Duration: up to 4-8 weeks if bony involvement seen on CT/MRI
• For Aspergillus species, it is treated with voriconazole for at least 12 weeks