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Malignant otitis externa (MOE) is a severe variant of acute otitis externa (AOE) in which necrotizing inflammation of the external auditory canal (EAC) develops. MOE is usually caused by Pseudomonas aeruginosa and most frequently affects older adults and individuals with diabetes and/or immunosuppression. Clinical features of MOE include severe pain, an erythematous and edematous EAC, and otorrhea; granulation tissue is visible on otoscopy. Because of the rapid spread of infection, patients may have signs of complications (e.g., cranial nerve palsies secondary to osteomyelitis of the skull base) on initial presentation. Imaging and laboratory studies are recommended to confirm the diagnosis. Treatment is with IV antibiotics; surgery may be required for debridement or abscess drainage. The prognosis with treatment is good, with overall mortality < 10%.
- Severe, persistent ear pain and/or jaw pain 
- Symptoms of extension of infection, e.g.:
- Conductive hearing loss
- Red and swollen; EAC and periauricular soft tissue 
- Otoscopic findings: granulation tissue at the cartilage-bone junction of the EAC 
All patients require laboratory studies and imaging.
Laboratory studies 
- CBC: for WBC 
- BMP: for serum glucose and creatinine
- ESR and CRP 
- Culture of ear canal : Obtain a sample prior to initiating empiric antibiotics.
More than one imaging modality is often required.
- Modalities 
A negative CT scan does not exclude early MOE, as changes may not be evident until one-third of bone mineral is eroded. 
Surgical biopsy 
Consider if there is diagnostic uncertainty or insufficient response to treatment.
Antibiotic therapy 
Systemic antibiotic therapy: typically lasting for 6–8 weeks ; 
- Initial empiric therapy: Use two antipseudomonal agents from different classes for ≥ 2 weeks, e.g., ciprofloxacin PLUS one of the following:
- Once culture results are available, tailor antibiotics to sensitivities and continue for an additional 4–6 weeks.
- Local treatment 
- May be required in select cases, e.g., abscess drainage or debridement of
- Send any surgical specimens for pathology and microbiological testing.
- Urgent otolaryngology consult
- Patients typically require initial hospitalization followed by outpatient care for prolonged IV antibiotics.
Monitoring of treatment response 
- Overall mortality: < 10% 
- Rates may be higher in patients aged over 80 years or with significant comorbidities. 
MOE is a severe infection that can be lethal without prompt treatment. Death is most commonly caused by intracranial complications.