Pseudomonas aestus Isolation from the Nasal Cavity of a Cat with Chronic Rhinitis.

Simple Summary: A 9-years-old cat presenting signs of chronic respiratory disease was evaluated though rhinoscopy, and samples for histopathology and microbiological cultures were collected. Histopathology revealed chronic infiltration of mature lymphocytes and plasma cells, leading to a diagnosis of chronic lymphoplasmacytic rhinitis. No fungal growth was observed, but bacterial cultures revealed growth of an atypical bacterium mistakenly identified with conventional bacterial identification methods. This isolate was later identified as P. aestus by sequencing followed by homologous sequences analysis, corresponding to an environmental strain of Pseudomonas used in agricultural settings as a biocide. Antimicrobial susceptibility testing was performed, and this P. aestus isolate presented a multidrug resistant profile. Pseudomonas are ubiquitous bacteria frequently described as animal and human opportunistic pathogens, and P. aeruginosa is the principal species related with animal disease. This work aims to report the first case of animal disease related with P. aestus, to the author's best knowledge. Furthermore, it highlights the need to establishing protocols aiming at the identification and characterization of non-traditional, multidrug-resistant Pseudomonas in the clinical setting. The Pseudomonas genus includes ubiquitous bacteria frequently described as animal and human opportunistic pathogens. A 9-year-old cat was referred for rhinoscopy at the Veterinary Hospital of the Faculty of Veterinary Medicine, University of Lisbon, Portugal, for an investigation of the chronic respiratory signs. Upon rhinoscopy, nasal and nasopharyngeal discharge were observed, and the nasal turbinates showed signs of inflammation. The nasal biopsies were evaluated by histopathology and mycological and bacterial cultures. The histopathology revealed chronic lymphoplasmacytic inflammation. The mycological culture was negative, but the bacterial culture revealed the growth of a bacterial isolate in the pure culture, identified as P. aestus by the sequencing of a 1750 bp PCR amplicon obtained with BCR1 and BCR2 primers, followed by homologous sequences analysis using the NCBI database. The isolate's susceptibility profile towards 14 antimicrobials was evaluated through the disk diffusion method, being observed that it presented a multidrug resistance profile. The studies available on this environmental Pseudomonas strain focused on its potential use for biocide production and application in agricultural settings, and, to the authors' best knowledge, there are no reports describing its association with infectious diseases in humans or animals, highlighting the importance of establishing protocols aiming at the identification and characterization of non-traditional, multidrug-resistant Pseudomonas in the clinical setting. [ABSTRACT FROM AUTHOR]