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Raoultella ornithinolytica is a bacterium belonging to the family Enterobacteriacae . It is a rare but emergent cause of human pathologies especially in immunocompromised patients. We 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. We performed right ear swab for culture examination, meanwhile we started empirical therapy with topic administration of neomycin, without any clinical improvement. The 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., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2020 Michele Cavaliere et al.)

Objectives: Magnetic resonance imaging (MRI) and in particular diffusion-weighted imaging (DWI) have been broadly proven to be the reference imaging method to discriminate between cholesteatoma and noncholesteatomatous middle ear lesions, especially when high tissue specificity is required. The aim of this study is to define a range of apparent diffusion coefficient (ADC) values within which the diagnosis of cholesteatoma is almost certain., Methods: The study was retrospectively conducted on a cohort of 124 patients. All patients underwent first- or second-look surgery because primary or secondary acquired cholesteatoma was clinically suspected; they all had preoperative MRI examination 15 days before surgery, including DWI from which the ADC maps were calculated., Results: Average ADC value for cholesteatomas was 859,4 × 10 -6  mm 2 /s (range 1545 × 10 -6  mm 2 /s; IQR = 362 × 10 -6  mm 2 /s; σ = 276,3 × 10 -6  mm 2 /s), while for noncholesteatomatous inflammatory lesions, it was 2216,3 × 10 -6  mm 2 /s (range 1015 × 10 -6  mm 2 /s; IQR = 372,75 × 10 -6  mm 2 /s; σ = 225,6 × 10 -6  mm 2 /s). Interobserver agreement with Fleiss' Kappa statistics was 0,96. No overlap between two groups' range of values was found and the difference was statistically significant for p < 0.0001., Conclusions: We propose an interval of ADC values that should represent an appropriate benchmark range for a correct differentiation between cholesteatoma and granulation tissue or fibrosis of noncholesteatomatous inflammatory lesions.