Necrotizing External Otitis: “Malignant” Once More

Methods: We conducted a retrospective chart review of patients who were hospitalized with malignant external otitis (MEO) at our tertiary care institution during the years 2012–2015. Host factors, microbiology including sensitivity data, antibiotic therapy, surgical interventions, and clinical course were analyzed.

Results: Ten patients with MEO were identified. Four of ten patients had bacterial isolates (three Pseudomonas aeruginosa and one Proteus mirabilis) that developed fluoroquinolone resistance during treatment. All four of these patients had progressive disease courses resulting in cranial neuropathies, abscesses, and bony sequestration. Nine patients were diabetic. Four patients had end-stage renal disease. All four of these patient had complications from MEO, three of whom expired due to co-morbidities following treatment for their MEO. One patient was immunosuppressed for a kidney and pancreas transplant. This patient expired from complications of MEO.

Discussion: Our recent clinical experience suggests we have entered a new era of MEO characterized by more relentless disease with poorer outcomes including mortalities. Failure of conventional drugs, more aggressive strains of bacteria, and more debilitated patients with multiple medical co-morbidities have all contributed to this unwelcome trend. A contributing factor to these poor outcomes is the increasing virulence and antibiotic resistance of the bacteria responsible for the infection. Both of the patients that grew out pansensitive Pseudomonas aeruginosa that developed resistance to quinolones after treatment with oral ciprofloxacin expired in the months following treatment for MEO. Patients with multiple medical co-morbidities present host factors that create additional challenges. Our current series reveals other illnesses in addition to diabetes such as ESRD and anti-rejection immunosuppresion that contribute to decreased host defenses and add complexity to the patient’s care. Of note, three of the four patients on hemodialysis expired following their treatment for MEO and the fourth is doing poorly. Antibiotic nephrotoxicity becomes even more of a concern in ESRD patients. ESRD, immunosuppression, and the development of bacterial resistance to antibiotics portend a poor prognosis. Patients will suffer from a progressive and destructive disease despite culture-directed antibiotic therapy. Additionally, some patients will succumb to the “malignant” nature of the external otitis.