{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,30]],"date-time":"2025-07-30T16:00:52Z","timestamp":1753891252955,"version":"3.41.2"},"reference-count":23,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,7,2]],"date-time":"2025-07-02T00:00:00Z","timestamp":1751414400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Med."],"abstract":"<jats:sec><jats:title>Introduction<\/jats:title><jats:p>Malignant otitis externa (MOE) is a severe and potentially life-threatening infection of the external auditory canal, most frequently caused by <jats:italic>Pseudomonas aeruginosa<\/jats:italic>. Although typically seen in immunocompromised individuals\u2014especially those with diabetes mellitus\u2014up to 45% of cases have been reported in non-diabetic patients, highlighting the importance of recognizing atypical presentations. Rare pathogens, such as <jats:italic>Proteus mirabilis<\/jats:italic>, 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.<\/jats:p><\/jats:sec><jats:sec><jats:title>Objectives<\/jats:title><jats:p>This report describes a really uncommon case of malignant otitis externa caused by <jats:italic>P. mirabilis<\/jats:italic> in a non-diabetic, immunocompetent patient.<\/jats:p><\/jats:sec><jats:sec><jats:title>Case presentation<\/jats:title><jats:p>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 <jats:italic>Proteus mirabilis<\/jats:italic>, resistant to multiple antibiotics but sensitive to piperacillin\/tazobactam, which was administered with supportive care. After 17\u202fdays 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.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>This case report highlights an exceptionally rare occurrence of MEO caused by <jats:italic>P. mirabilis<\/jats:italic> 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.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fmed.2025.1577525","type":"journal-article","created":{"date-parts":[[2025,7,2]],"date-time":"2025-07-02T05:51:57Z","timestamp":1751435517000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Expanding the diagnostic spectrum of malignant otitis externa: a case report of proteus infection in a non-immunosuppressed patient"],"prefix":"10.3389","volume":"12","author":[{"given":"Fabi\u00e1n Dar\u00edo","family":"Arias Rodr\u00edguez","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mercedes","family":"Larenas","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Santiago","family":"Paredes","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guillermina","family":"Giuliano","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Andr\u00e9s","family":"L\u00f3pez-Cort\u00e9s","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Juan S.","family":"Izquierdo-Condoy","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2025,7,2]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"109","DOI":"10.1177\/000348948109000203","article-title":"Temporal bone histopathology of necrotizing external otitis. 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