CASE REPORT article
Front. Med.
Sec. Infectious Diseases: Pathogenesis and Therapy
Volume 12 - 2025 | doi: 10.3389/fmed.2025.1577525
Expanding the diagnostic spectrum of Malignant Otitis Externa: A case report of proteus Infection in a non-immunosuppressed patient
Provisionally accepted
Fabian Darío Arias Rodríguez1
Mercedes Larenas1Santiago Paredes1Guillermina Giuliano1Andrés López-Cortés2
Juan S. Izquierdo-Condoy2*- 1Department of Otorhinolaryngology, Hospital Dr. Ricardo Gutierrez de La Plata, La Plata, Argentina
- 2University of the Americas, Quito, Ecuador
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Introduction: Malignant otitis externa (MOE) is a severe and potentially life-threatening infection of the external auditory canal, most frequently caused by Pseudomonas aeruginosa. Although typically seen in immunocompromised individuals-especially those with diabetes mellitus-up to 45% of cases have been reported in non-diabetic patients, highlighting the importance of recognizing atypical presentations. Rare pathogens, such as Proteus mirabilis, have been identified in only a few documented cases. Early diagnosis and prompt intervention are essential to prevent serious complications, including osteomyelitis and intracranial extension.Objectives: This report describes a really uncommon case of malignant otitis externa caused by P. mirabilis in a non-diabetic, immunocompetent patient.A 53-year-old male with no relevant medical history presented with a four-month history of left-sided otorrhea, otalgia, and preauricular pain. Examination and imaging revealed purulent discharge and bone erosion, suggestive of MOE. Empirical treatment with amoxicillin/clavulanic acid was ineffective. Culture identified Proteus mirabilis, resistant to multiple antibiotics but sensitive to piperacillin/tazobactam, which was administered with supportive care. After 17 days of intravenous therapy, the patient improved and was discharged on oral ciprofloxacin to complete a three-month course. Follow-up confirmed clinical resolution without recurrence.This case report highlights an exceptionally rare occurrence of MEO caused by P. mirabilis in an immunocompetent, non-diabetic patient. It emphasizes the need to consider uncommon pathogens and atypical clinical profiles in MOE. Early diagnosis, microbiological confirmation, and tailored antimicrobial therapy were critical for favorable outcomes.
Keywords: Malignant otitis externa, Proteus mirabilis, Atypical presentation, Targeted antibiotic therapy, Non-immunocompromised patient
Received: 15 Feb 2025; Accepted: 12 Jun 2025.
Copyright: © 2025 Arias Rodríguez, Larenas, Paredes, Giuliano, López-Cortés and Izquierdo-Condoy. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Juan S. Izquierdo-Condoy, University of the Americas, Quito, Ecuador
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