A 68-year-old man presents to the emergency department with right ear pain that he developed 4 days prior, and it has progressively worsened. The pain is worse at night. He has associated fever and chills. This morning, he awoke with purulent, foul-smelling discharge on his pillow. He has a history of type II diabetes mellitus and hypertension. He takes metformin, insulin, and lisinopril. His temperature is 102.2°F (39.0°C), blood pressure is 130/87 mmHg, pulse is 110/min, and respirations are 16/min. The patient is toxic in appearance and in mild distress due to pain. Examination of the external ear reveals findings shown in Figure A. Granulation tissue and purulent drainage are noted in the external auditory canal. Physical exam is otherwise unremarkable. Which of the following is the most appropriate therapy for this patient?
Ceftriaxone
Ofloxacin ear drops
Amoxicillin
Vancomycin and piperacillin-tazobactam
Vancomycin and piperacillin-tazobactam
The patient in this vignette most likely has malignant otitis externa (also referred to as necrotizing otitis externa), which is a life-threatening infection requiring therapy with intravenous anti-pseudomonal and broad-spectrum antibiotics. Piperacillin-tazobactam and vancomycin is an appropriate initial regimen.

Malignant otitis externa is an invasive infection of the external auditory canal and skull base, and is seen almost exclusively in immunocompromised patients. Patients with poorly controlled type II diabetes mellitus are at particularly increased risk. The infection spreads from the floor of the ear canal to the nearby tissues including the bones at the base of the skull and the temporomandibular joint. The resulting skull base osteomyelitis distinguishes the "necrotizing" or "malignant" presentation of otitis externa. Patients often present with severe otalgia and purulent drainage from the external auditory canal. Granulation tissue in the external auditory canal is a characteristic exam finding. Pseudomonas aeruginosa is the causative organism in most cases of necrotizing otitis externa. Therefore, intravenous antibiotics with sufficient coverage of Pseudomonas are the therapy of choice. As infection progresses, involvement of cranial nerves with resultant palsy may be observed.

Aaraj et. al review the clinical manifestations, diagnosis and management of malignant otitis externa. They note the risk for this disease among patients with diabetes or other etiologies of an immunocompromised state. They recommend management with intravenous ciprofloxacin.

Figure A shows the external ear of a patient with malignant otitis externa. Note the classic granulation tissue at the cartilage-bone junction and crusted, purulent discharge.

Incorrect Answers:
Answer A: Intravenous acyclovir would be appropriate for suspected herpes zoster, which may present with ear pain and a vesicular rash in the external auditory canal. This patient's granulation tissue in the external auditory canal and purulent drainage make malignant otitis externa more likely.

Answer B: Oral amoxicillin may be appropriate for management of acute otitis media which presents with ear pain and a distended tympanic membrane that is immobile.

Answer C: Ceftriaxone is appropriate coverage for cellulitis which presents with warmth, erythema, and tenderness of the skin. It would be too narrow of spectrum to treat malignant otitis externa.

Answer E: Topical ofloxacin may be appropriate for some cases of simple otitis externa ("swimmer's ear") which presents with ear pain and drainage in young, healthy patients who swim regularly. Patients are well-appearing.

Bullet Summary:
Malignant otitis externa is an invasive infection of the external auditory canal and skull base that requires management with broad-spectrum intravenous antibiotics that cover Pseudomonas aeruginosa.