Malignant Otitis Externa: An Evolving Disease

Abstract

Objectives: 1) Compare the clinical presentations and outcomes of patients with MOE caused by Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA). 2) Recognize the evolving trend of atypical and drug-resistant organisms causing malignant otitis externa (MOE). Methods: A retrospective review of disease course and outcome was performed of patients diagnosed with MOE at a tertiary referral center between 1995 and 2012. Results: Forty-four patients with a diagnosis of MOE were identified. Eighteen patients were excluded due to insufficient or inconsistent clinical data, leaving 26 patients for analysis. Forty-six percent of patient cultures grew Pseudomonas and 12% grew MRSA. All patients infected with Pseudomonas had diabetes mellitus, compared to 33% of MRSA-infected patients ( P < 0.05). Twenty-five percent of Pseudomonas-infected patients presented with at least one cranial nerve palsy, as compared to none of the MRSA-infected patients (ns). Duration of therapy for Pseudomonas-infected patients lasted an average of 7.2 weeks, while MRSA-infected patients lasted 10 weeks (ns). Excluding failed initial treatment courses, the average treatment durations were 5.0 and 7.7 weeks for Pseudomonas and MRSA infections, respectively. Other atypical pathogenic organisms isolated in culture include Candida, Aspergillus, and Enterococcus species. Conclusions: Increasingly, MOE is being caused by organisms other than Pseudomonas, including MRSA. Empiric treatment, without culture, can lead to delays in definitive therapy. A high index of suspicion for atypical or drug resistant organisms should be maintained in MOE patients who are not diabetic. Culture directed therapy for treatment of MOE is paramount.