Medical Musing of The Week: Malignant Otitis Externa

Overview

  • Begins as simple otitis externa and extends to the bony ear canal and the soft tissues deep of ear canal
  • Older adults and Diabetes are risk factors (also patients who are immunocompromised in anyway)

Etiology/Pathogenesis/Risk Factors

  • Causative Organism: Pseudomonas aeruginosa 
  • Almost always have glucose intolerance
  • The degree of glucose intolerance does not correlate with development of malignant otitis externa or the severity of the disease that develops
  • Water contaminated with P. Aeruginosa
  • Earbuds, hearing aids and swim caps (anything that occludes the ear)
  • Prior radiation therapy

Clinical Manifestations

  • Otalgia (likely occurring at night)
  • Otorrhea (foul smelling)
  • Fever
  • Facial weakness
  • Pain in TMJ when chewing
  • Obvious infection in the external auditory canal
  • Granulated tissue on floor of ear canal

Diagnosis

  • Clinical based on history and physical exam
  • Prolonged exposure to water
  • Elevated ESR & CRP
  • Gram Stain

Treatment

  • Ciprofloxacin: 400 mg intravenously [IV] every 8 hours or 750 mg orally every 12 hours
  • Levofloxacin 750mg daily (every 48 hours if significant renal impairment)
  • Patients generally need IV therapy until a clinical improvement is observed
  • Duration of therapy is usually at least 6 weeks
  • If resistant to fluroquinolone, admit for biopsy and debridement to determine sensitivity to other antibiotics. (ie: piperacillin-tazobactam, ceftazidime, cefepime)

Complications & Prognosis

  • Watch out for resistance to Ciprofloxacin in patients aren’t responding
  • Potential for Osteomyelitis in base of the skull
  • Cranial nerve involvement

 

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