Malignant otitis externa is an aggressive infection that starts in the external ear canal and spreads quickly to surrounding soft tissues and skull base bones. It is caused most commonly by Pseudomonas aeruginosa bacteria and patients with diabetes or AIDS are more susceptible. Diagnosis involves examination finding of ear pain, drainage and swelling supported by positive bone scans. Treatment requires prolonged high dose antibiotic therapy directly into veins or muscles along with surgery to remove dead tissue when needed.