Case Report Unusual Localization of an Emergent Bacterium, Raoultella ornithinolytica Michele Cavaliere, 1 Guido Bartoletti, 1 Pasquale Capriglione, 1 AntonellaMiriamDiLullo , 1 GaetanoMotta, 2 Maurizio Iengo, 1 andElenaCantone 1 1 Department of Neuroscience, Reproductive and Odontostomatological Sciences—ENT Section, University “Federico II”, Naples, Italy 2 Otorhinolaryngology, Head and Neck Surgery Unit, Department of Mental and Physical Health and Preventive Medicine, Universit` a degli Studi della Campania Luigi Vanvitelli, Naples, Italy Correspondence should be addressed to Elena Cantone; elenacantone@libero.it Received 20 October 2019; Revised 4 February 2020; Accepted 25 February 2020; Published 30 March 2020 Academic Editor: Georgios D. Kotzalidis Copyright © 2020 Michele Cavaliere et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Raoultella ornithinolytica is a bacterium belonging to the family Enterobacteriacae. It is a rare but emergent cause of human pathologies especially in immunocompromised patients. e described the first case in the literature of isolated external otitis sustained by Raoultella ornithinolytica in an immunocompetent host. A 54-year-old Caucasian man with a history of previous myringoplasty came to our attention reporting otalgia and otorrhea. e performed right ear swab for culture examination, meanwhile we started empirical therapy with topic administration of neomycin, without any clinical improvement. e cultural examination showed the presence of a Raoultella ornithinolytica infection. After ten days of treatment with oral ciprofloxacin and topic levofloxacin, there was the complete resolution of pain and inflammation. Raoultella ornithinolytica must be taken into consideration as an emergent cause of human infection, also in case of external otitis. Infection can be severe and can occur both in immunocompromised and in immunocompetent hosts. Culture test is mandatory to choose the proper therapy and avoid potential severe complications. 1.Introduction Raoultella ornithinolytica is a gram-negative, capsulate, aerobic, and nonmotile bacterium belonging to the family Enterobacteriacae. ree species of Raoultella, initially classified as Klebsiella, exist, R. electrica, R. planticola, and R. terrigena [1, 2]. ese bacteria have been isolated from aquatic environments, fish, and ticks, where it can produce histamine because of histidine decarboxylase enzyme and can contaminate food, especially not well conserved fish and pork [3]. Histamine toxicity produces symptoms that in- clude flushing of skin, headache, pruritus, and abdominal cramping [3]. is rare but emergent bacterium can cause a wide spectrum of clinical manifestations. For instance, human infections caused by R. ornithinolytica are rare but can be responsible for bacteraemia, especially in patient with malignancies and immunodeficiencies [4, 5]. Furthermore, R. ornithinolytica is responsible for urinary, bile tract, tra- cheal, bronchial, and lungs infections in patients with im- munodeficiency. e majority of cases reported in the literature are community acquired infections, especially nosocomial [6]. Neonatal sepsis is rare; however, it can be severe if not treated [7], as well as septic arthritis of the temporomandibular joint. In a case report after an early but temporary response to the antibiotic therapy, this bacterium leads to a complete demolition of the articulation [8]. R. ornithinolytica not only expresses β-lactamase, which pro- vides resistance to commonly used β-lactam antibiotics but can also acquire genes for multi-drug resistance [8, 9]. Only a few ear, nose, and throat cases complaining difficulty in swallowing, pain in the throat, rhinosinusitis, and dysphonia are described in the literature. e described Hindawi Case Reports in Medicine Volume 2020, Article ID 1710271, 3 pages https://doi.org/10.1155/2020/1710271