{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T18:59:05Z","timestamp":1789066745480,"version":"build-2803163510"},"reference-count":43,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,21]],"date-time":"2026-07-21T00:00:00Z","timestamp":1784592000000},"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. Vet. Sci."],"abstract":"\n Background<\/jats:title>\n \n Pseudomonas aeruginosa<\/jats:italic>\n is a clinically important opportunistic pathogen in canine otitis externa, particularly in chronic, recurrent or treatment-refractory cases. Its low outer-membrane permeability, biofilm-forming capacity, efflux systems and ability to acquire additional resistance determinants complicate empirical therapy and make local surveillance essential.\n <\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n This study integrated broth microdilution-based minimum inhibitory concentration (MIC) testing with whole-genome analysis to characterize antimicrobial susceptibility patterns and genomic resistance determinants in canine otitis-associated\n P. aeruginosa<\/jats:italic>\n isolates from Hungary. A total of 110 isolates were tested against 14 antimicrobial or antiseptic agents. Official clinical breakpoints and European Committee on Antimicrobial Susceptibility Testing (EUCAST) epidemiological cut-off values were applied where available, while agents lacking validated interpretive criteria were evaluated descriptively. A phenotypically selected subset of 70 isolates, chosen to cover the major MIC ranges, resistance profiles and modified MAR-index spectrum observed in the full collection, was subjected to long-read sequencing, and all 70 genome assemblies were included in comprehensive antibiotic resistance database (CARD)-based resistance gene screening, multi-locus sequence typing (MLST) and genome quality assessment.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n High frequencies of elevated MICs were detected for several clinically relevant agents. The highest proportions above interpretive thresholds were observed for enrofloxacin (109\/110, 99.1%), marbofloxacin (99\/110, 90.0%), piperacillin-tazobactam (75\/110, 68.2%), ceftazidime (71\/110, 64.5%) and tobramycin (62\/110, 56.4%). The median modified multiple-antimicrobial-resistance index, calculated only from agents with interpretable resistance thresholds, was 0.56. Genomic analysis showed a broad intrinsic resistance background dominated by efflux-associated determinants and recurrent aminoglycoside, beta-lactam and fluoroquinolone-associated genes, including\n APH(3\u2032)-IIb<\/jats:italic>\n , Mex-family efflux components, Opr-associated transporters,\n arnA<\/jats:italic>\n ,\n basS<\/jats:italic>\n , PDC\/OXA beta-lactamases and\n crpP<\/jats:italic>\n in a subset of isolates.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusion<\/jats:title>\n \n These findings support the need for culture- and MIC-guided therapy in canine\n P. aeruginosa<\/jats:italic>\n otitis and support the value of including companion-animal clinical isolates in national and regional antimicrobial resistance surveillance frameworks.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fvets.2026.1902036","type":"journal-article","created":{"date-parts":[[2026,7,21]],"date-time":"2026-07-21T04:19:48Z","timestamp":1784607588000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":2,"title":["Phenotypic antimicrobial susceptibility and genomic resistance determinants in canine otitis-associated Pseudomonas aeruginosa isolates"],"prefix":"10.3389","volume":"13","author":[{"given":"Merc\u00e9desz Adrienn","family":"Veres","sequence":"first","affiliation":[{"name":"Department of Pharmacology and Toxicology, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]},{"name":"National Laboratory of Infectious Animal Diseases, Antimicrobial Resistance, Veterinary Public Health and Food Chain Safety, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zs\u00f3fia Anna","family":"T\u00f3th","sequence":"additional","affiliation":[{"name":"Department of Pharmacology and Toxicology, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Enik\u0151","family":"Ill\u00e9s","sequence":"additional","affiliation":[{"name":"Department of Pharmacology and Toxicology, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patrik","family":"Mag","sequence":"additional","affiliation":[{"name":"Department of Pharmacology and Toxicology, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]},{"name":"National Laboratory of Infectious Animal Diseases, Antimicrobial Resistance, Veterinary Public Health and Food Chain Safety, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eszter","family":"Kaszab","sequence":"additional","affiliation":[{"name":"National Laboratory of Infectious Animal Diseases, Antimicrobial Resistance, Veterinary Public Health and Food Chain Safety, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]},{"name":"Department of Bioinformatics, One Health Institute, Faculty of Health Sciences, University of Debrecen","place":["Debrecen, Hungary"]},{"name":"Department of Microbiology and Infectious Diseases, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Enik\u0151","family":"Feh\u00e9r","sequence":"additional","affiliation":[{"name":"National Laboratory of Infectious Animal Diseases, Antimicrobial Resistance, Veterinary Public Health and Food Chain Safety, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]},{"name":"Department of Microbiology and Infectious Diseases, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]},{"name":"National Laboratory of Virology, Szent\u00e1gothai Research Centre, University of P\u00e9cs","place":["P\u00e9cs, Hungary"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u00c1d\u00e1m","family":"Kerek","sequence":"additional","affiliation":[{"name":"Department of Pharmacology and Toxicology, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]},{"name":"National Laboratory of Infectious Animal Diseases, Antimicrobial Resistance, Veterinary Public Health and Food Chain Safety, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u00c1kos","family":"Jerzsele","sequence":"additional","affiliation":[{"name":"Department of Pharmacology and Toxicology, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]},{"name":"National Laboratory of Infectious Animal Diseases, Antimicrobial Resistance, Veterinary Public Health and Food Chain Safety, University of Veterinary Medicine Budapest","place":["Budapest, Hungary"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,7,21]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"2650","DOI":"10.3390\/microorganisms11112650","article-title":"Pseudomonas spp. in canine otitis externa","volume":"11","author":"Secker","year":"2023","journal-title":"Microorganisms"},{"key":"ref2","first-page":"97","article-title":"Canine otitis externa \u2014 treatment and complications","volume":"60","author":"Bajwa","year":"2019","journal-title":"Can Vet J"},{"key":"ref3","doi-asserted-by":"publisher","first-page":"7","DOI":"10.1136\/inp.i470","article-title":"Discovering the causes of otitis externa","volume":"38","author":"Paterson","year":"2016","journal-title":"In 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