{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,27]],"date-time":"2026-10-27T20:28:31Z","timestamp":1793132911914,"version":"4.5.0"},"reference-count":54,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2025,7,6]],"date-time":"2025-07-06T00:00:00Z","timestamp":1751760000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"new research initiatives at the City University of Hong Kong to Ibrahim Elsohaby","award":["9610583"],"award-info":[{"award-number":["9610583"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Background: Canine pyoderma and otitis externa are prevalent bacterial skin infections in veterinary practice, frequently complicated by the emergence of multidrug-resistant (MDR) pathogens. Objectives: To investigate the frequency, antimicrobial resistance (AMR) profiles, and frequency of MDR bacterial isolates from dogs with pyoderma or otitis externa in Hong Kong. Methods: A retrospective study of bacterial isolates from 215 clinical samples collected from dogs presenting with pyoderma (n = 63) or otitis externa (n = 152) at veterinary clinics across Hong Kong between 2018 and 2022. Bacterial isolates were identified and subjected to antimicrobial susceptibility testing against 13 antimicrobial classes. Results: Staphylococcus spp., particularly S. pseudintermedius, were the most commonly isolated species, followed by Pseudomonas spp. and Proteus spp. High resistance rates were observed for orbifloxacin (61.3% in pyoderma; 76.7% in otitis externa), doxycycline (59.3%; 69.2%), clindamycin (62%; 68.9%), and enrofloxacin (50%; 55.5%). Most isolates were sensitive to ofloxacin, ticarcillin\u2013clavulanate, tobramycin, ciprofloxacin, cefpodoxime, cefuroxime, and cefixime. MDR was detected in 67.5% of pyoderma and 66.8% of otitis externa isolates. Gram-negative bacteria exhibited significantly higher MDR rates than Gram-positive isolates. The multiple antibiotic resistance (MAR) index averaged 0.41 for pyoderma and 0.52 for otitis externa isolates. We found no significant associations between MDR and non-modifiable risk factors (i.e., age, sex, breed, and reproductive status). Conclusions: These findings highlight the critical need for prudent antimicrobial use and continuous surveillance of AMR trends in companion animals. A higher focus should be placed on topical antiseptic therapy, with oral antibiotics used only in exceptional cases and after susceptibility testing. From a One Health perspective, the potential transmission of MDR bacteria between companion animals and humans underscores the importance of a coordinated approach to antimicrobial stewardship across both veterinary and human medicine.<\/jats:p>","DOI":"10.3390\/antibiotics14070685","type":"journal-article","created":{"date-parts":[[2025,7,7]],"date-time":"2025-07-07T10:03:27Z","timestamp":1751882607000},"page":"685","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Canine Pyoderma and Otitis Externa: A Retrospective Analysis of Multidrug-Resistant Bacterial Carriage in Hong Kong"],"prefix":"10.3390","volume":"14","author":[{"given":"Wing Yu","family":"Chan","sequence":"first","affiliation":[{"name":"Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong SAR 999077, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4517-7729","authenticated-orcid":false,"given":"Stefan","family":"Hobi","sequence":"additional","affiliation":[{"name":"Department of Veterinary Clinical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong SAR 999077, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew","family":"Ferguson","sequence":"additional","affiliation":[{"name":"CityU Veterinary Diagnostic Laboratory Co., Ltd., City University of Hong Kong, Hong Kong SAR 999077, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2533-988X","authenticated-orcid":false,"given":"Ibrahim","family":"Elsohaby","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases and Public Health, Jockey Club of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong SAR 999077, China"},{"name":"Centre for Applied One Health Research and Policy Advice (OHRP), City University of Hong Kong, Hong Kong SAR 999077, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,6]]},"reference":[{"key":"ref_1","first-page":"204","article-title":"Canine superficial pyoderma and therapeutic considerations","volume":"57","author":"Bajwa","year":"2016","journal-title":"Can. Vet. J."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"434","DOI":"10.1136\/vr.104420","article-title":"Recurrent pyoderma and its underlying primary diseases: A retrospective evaluation of 157 dogs","volume":"182","author":"Seckerdieck","year":"2018","journal-title":"Vet. Rec."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/j.tvjl.2018.04.002","article-title":"What has changed in canine pyoderma? A narrative review","volume":"235","author":"Loeffler","year":"2018","journal-title":"Vet. J."},{"key":"ref_4","first-page":"1231","article-title":"Pseudomonas otitis externa in dogs","volume":"59","author":"Pye","year":"2018","journal-title":"Can. Vet. J."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"449","DOI":"10.24425\/pjvs.2023.145052","article-title":"Prevalence of the microbiological causes of canine otitis externa and the antibiotic susceptibility of the isolated bacterial strains","volume":"26","author":"Tesin","year":"2023","journal-title":"Pol. J. Vet. Sci."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"459","DOI":"10.1016\/j.cvsm.2003.10.006","article-title":"Causes of otitis externa","volume":"34","author":"Rosser","year":"2004","journal-title":"Vet. Clin. Small Anim. Pract."},{"key":"ref_7","first-page":"1","article-title":"Frequency and predisposing factors for canine otitis externa in the UK\u2013a primary veterinary care epidemiological view","volume":"8","author":"Volk","year":"2021","journal-title":"Canine Med. Genet."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Kwon, J., Ko, H.J., Yang, M.H., Park, C., and Park, S.C. (2022). Antibiotic resistance and species profile of Enterococcus species in dogs with chronic otitis externa. Vet. Sci., 9.","DOI":"10.3390\/vetsci9110592"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1084","DOI":"10.1111\/jam.14868","article-title":"Changes in the ear canal microbiota of dogs with otitis externa","volume":"130","author":"Kasai","year":"2021","journal-title":"J. Appl. Microbiol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"229","DOI":"10.2460\/ajvr.1986.47.02.229","article-title":"Frequency and antimicrobial susceptibility of Staphylococcus species isolated from canine pyodermas","volume":"47","author":"Medleau","year":"1986","journal-title":"Am. J. Vet. Res."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"2340","DOI":"10.14202\/vetworld.2023.2340-2348","article-title":"Methicillin-resistant Staphylococci in canine pyoderma in Thailand","volume":"16","author":"Putriningsih","year":"2023","journal-title":"Vet. World"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"384","DOI":"10.1016\/j.apjtb.2015.11.012","article-title":"An update on microbiological causes of canine otitis externa in Campania Region, Italy","volume":"6","author":"Nocera","year":"2016","journal-title":"Asian Pac. J. Trop. Biomed."},{"key":"ref_13","first-page":"695","article-title":"Antimicrobial therapy of skin and ear infections","volume":"37","author":"Dowling","year":"1996","journal-title":"Can. Vet. J."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Silva, V., Oliveira, A., Manageiro, V., Cani\u00e7a, M., Contente, D., Capita, R., Alonso-Calleja, C., Carvalho, I., Capelo, J.L., and Igrejas, G. (2021). Clonal diversity and antimicrobial resistance of methicillin-resistant Staphylococcus pseudintermedius isolated from canine pyoderma. Microorganisms, 9.","DOI":"10.3390\/microorganisms9030482"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1111\/j.1439-0450.2004.00816.x","article-title":"Antimicrobial drug susceptibility of Staphylococcus intermedius clinical isolates from canine pyoderma","volume":"52","author":"Ganiere","year":"2005","journal-title":"J. Vet. Med. B"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"304-e369","DOI":"10.1111\/vde.12444","article-title":"Recommendations for approaches to meticillin-resistant staphylococcal infections of small animals: Diagnosis, therapeutic considerations and preventative measures. Clinical Consensus Guidelines of the World Association for Veterinary Dermatology","volume":"28","author":"Morris","year":"2017","journal-title":"Vet. Dermatol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1038\/emi.2015.8","article-title":"Strategic measures for the control of surging antimicrobial resistance in Hong Kong and mainland of China","volume":"4","author":"Cheng","year":"2015","journal-title":"Emerg. Microbes Infect."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1111\/j.1863-2378.2009.01286.x","article-title":"Low rate of methicillin-resistant coagulase-positive staphylococcal colonization of veterinary personnel in Hong Kong","volume":"58","author":"Boost","year":"2011","journal-title":"Zoonoses Public Health."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Rhouma, M., Archambault, M., and Butaye, P. (2023). Antimicrobial use and resistance in animals from a one health perspective. Vet. Sci., 10.","DOI":"10.3390\/vetsci10050319"},{"key":"ref_20","first-page":"1764","article-title":"Antibiotic resistance profiles of Staphylococcus pseudintermedius isolates from canine patients in Korea","volume":"20","author":"Yoon","year":"2010","journal-title":"J. Microbiol. Biotechnol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"623","DOI":"10.1111\/j.1365-2672.2012.05233.x","article-title":"Methicillin-resistant Staphylococcus pseudintermedius isolated from canine pyoderma in North China","volume":"112","author":"Wang","year":"2012","journal-title":"J. Appl. Microbiol."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Tanveer, M., Ntakiyisumba, E., Hirwa, F., Yoon, H., Oh, S.-I., Kim, C., Kim, M.H., Yoon, J.-S., and Won, G. (2024). Prevalence of bacterial pathogens isolated from canines with pyoderma and otitis externa in Korea: A systematic review and meta-analysis. Vet. Sci., 11.","DOI":"10.3390\/vetsci11120656"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Rosales, R.S., Ram\u00edrez, A.S., Moya-Gil, E., de la Fuente, S.N., Su\u00e1rez-P\u00e9rez, A., and Poveda, J.B. (2024). Microbiological survey and evaluation of antimicrobial susceptibility patterns of microorganisms obtained from suspect cases of canine otitis externa in Gran Canaria, Spain. Animals, 14.","DOI":"10.3390\/ani14050742"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Chehida, F.B., Tombari, W., Gharsa, H., Rabia, Y., Ferhi, S., Jrad, M., and Messadi, L. (2024). New insights into molecular characterization, antimicrobial resistance and virulence factors of methicillin-sensitive coagulase-positive Staphylococcus spp. from dogs with pyoderma and otitis externa. Microbiol. Res., 15.","DOI":"10.3390\/microbiolres15030081"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1254","DOI":"10.1111\/jam.13287","article-title":"Antimicrobial susceptibility monitoring of dermatological bacterial pathogens isolated from diseased dogs and cats across Europe (ComPath results)","volume":"121","author":"Ludwig","year":"2016","journal-title":"J. Appl. Microbiol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1337","DOI":"10.2460\/ajvr.67.8.1337","article-title":"Genotypic relatedness of staphylococcal strains isolated from pustules and carriage sites in dogs with superficial bacterial folliculitis","volume":"67","author":"Pinchbeck","year":"2006","journal-title":"Am. J. Vet. Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"e113","DOI":"10.1111\/vde.12290","article-title":"Antimicrobial resistance, integron carriage, and gyrA and gyrB mutations in Pseudomonas aeruginosa isolated from dogs with otitis externa and pyoderma in Brazil","volume":"27","author":"Arais","year":"2016","journal-title":"Vet. Dermatol."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Garcias, B., Batalla, M., Vidal, A., Dur\u00e1n, I., and Darwich, L. (2025). Trends in antimicrobial resistance of canine otitis pathogens in the Iberian Peninsula (2010\u20132021). Antibiotics, 14.","DOI":"10.3390\/antibiotics14040328"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"e121","DOI":"10.1017\/S0950268818003278","article-title":"Antimicrobial resistance patterns of bacteria isolated from dogs with otitis","volume":"147","author":"Cazeau","year":"2019","journal-title":"Epidemiol. Infect."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1016\/j.vetmic.2011.02.002","article-title":"Risk factors associated with the antimicrobial resistance of staphylococci in canine pyoderma","volume":"150","author":"Huerta","year":"2011","journal-title":"Vet. Microbiol."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Dinkova, V., and Rusenova, N. (2024). A retrospective study (2019\u20132023) on the prevalence and antimicrobial resistance of isolates from canine clinical samples submitted to the University Veterinary Hospital in Stara Zagora, Bulgaria. Microorganisms, 12.","DOI":"10.3390\/microorganisms12081670"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1111\/avj.12176","article-title":"Canine superficial bacterial pyoderma: Evaluation of skin surface sampling methods and antimicrobial susceptibility of causal Staphylococcus isolates","volume":"92","author":"Ravens","year":"2014","journal-title":"Aust. Vet. J."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Srednik, M.E., Perea, C.A., Giacoboni, G.I., Hicks, J.A., Foxx, C.L., Harris, B., and Schlater, L.K. (2023). Genomic features of antimicrobial resistance in Staphylococcus pseudintermedius isolated from dogs with pyoderma in Argentina and the United States: A comparative study. Int. J. Mol. Sci., 24.","DOI":"10.3390\/ijms241411361"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"106170","DOI":"10.1016\/j.prevetmed.2024.106170","article-title":"Longitudinal antimicrobial susceptibility trends of canine Staphylococcus pseudintermedius","volume":"226","author":"Calabro","year":"2024","journal-title":"Prev. Vet. Med."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1615","DOI":"10.1292\/jvms.10-0172","article-title":"Antimicrobial susceptibility and methicillin resistance in Staphylococcus pseudintermedius and Staphylococcus schleiferi subsp. coagulans isolated from dogs with pyoderma in Japan","volume":"72","author":"Kawakami","year":"2010","journal-title":"J. Vet. Med. Sci."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Wang, Q., Chen, S., Ma, S., Jiao, Y., Hong, H., Wang, S., Huang, W., An, Q., Song, Y., and Dang, X. (2025). Antimicrobial resistance and risk factors of canine bacterial skin infections. Pathogens, 14.","DOI":"10.3390\/pathogens14040309"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"447","DOI":"10.15547\/bjvm.2151","article-title":"Microbiological and antibacterial resistance profile in canine otitis externa--a comparative analysis","volume":"22","author":"Petrov","year":"2019","journal-title":"Bulg. J. Vet. Med."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"419","DOI":"10.1016\/j.tim.2011.04.005","article-title":"Pseudomonas aeruginosa: All roads lead to resistance","volume":"19","author":"Breidenstein","year":"2011","journal-title":"Trends Microbiol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1016\/j.biotechadv.2018.11.013","article-title":"Antibiotic resistance in Pseudomonas aeruginosa: Mechanisms and alternative therapeutic strategies","volume":"37","author":"Pang","year":"2019","journal-title":"Biotechnol. Adv."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"P\u0142\u00f3karz, D., Czopowicz, M., Bierowiec, K., and Rypu\u0142a, K. (2022). Virulence genes as markers for Pseudomonas aeruginosa biofilm formation in dogs and cats. Animals, 12.","DOI":"10.3390\/ani12040422"},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Meroni, G., Soares Filipe, J.F., Drago, L., and Martino, P.A. (2019). Investigation on antibiotic-resistance, biofilm formation and virulence factors in multi drug resistant and non multi drug resistant Staphylococcus pseudintermedius. Microorganisms, 7.","DOI":"10.3390\/microorganisms7120702"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"945","DOI":"10.1292\/jvms.15-0043","article-title":"Phenotypic and genotypic characterization of canine pyoderma isolates of Staphylococcus pseudintermedius for biofilm formation","volume":"77","author":"Proietti","year":"2015","journal-title":"J. Vet. Med. Sci."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"142","DOI":"10.1111\/j.1365-3164.2008.00663.x","article-title":"Screening for skin carriage of methicillin-resistant coagulase-positive staphylococci and Staphylococcus schleiferi in dogs with healthy and inflamed skin","volume":"19","author":"Griffeth","year":"2008","journal-title":"Vet. Dermatol."},{"key":"ref_44","first-page":"1021","article-title":"Antimicrobial resistance in Staphylococcus pseudintermedius and the molecular epidemiology of methicillin-resistant S. pseudintermedius in small animals in Finland","volume":"72","author":"Eklund","year":"2017","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"e20170738","DOI":"10.1590\/0103-8478cr20170738","article-title":"Frequency and antimicrobial susceptibility of Staphylococcus pseudintermedius in dogs with otitis externa","volume":"48","author":"Scherer","year":"2018","journal-title":"Ci\u00eancia Rural."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"559","DOI":"10.1111\/j.1439-0442.2007.00996.x","article-title":"Identification and antimicrobial susceptibility of bacteria and yeasts isolated from healthy dogs and dogs with otitis externa","volume":"54","author":"Lyskova","year":"2007","journal-title":"J. Vet. Med. A"},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"D\u00e9gi, J., Mo\u021bco, O.-A., D\u00e9gi, D.M., Suici, T., Mare\u0219, M., Imre, K., and Cristina, R.T. (2021). Antibiotic susceptibility profile of Pseudomonas aeruginosa canine isolates from a multicentric study in Romania. Antibiotics, 10.","DOI":"10.20944\/preprints202104.0561.v1"},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"White, S.D., and Cole, L.K. (2021). Pyoderma, Otitis Externa and Otitis Media. Greene\u2019s Infectious Diseases of the Dog and Cat, WB Saunders.","DOI":"10.1016\/B978-0-323-50934-3.00119-1"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"711","DOI":"10.1177\/10406387241233546","article-title":"Retrospective analysis of antimicrobial resistance in bacterial pathogens from pet rabbits in Hong Kong, 2019\u20132022","volume":"36","author":"Xin","year":"2024","journal-title":"J. Vet. Diagn. Investig."},{"key":"ref_50","unstructured":"Clinical and Laboratory Standards Institute (CLSI) (2025). Performance Standards for Antimicrobial Susceptibility Testing, Clinical and Laboratory Standards Institute. [35th ed.]."},{"key":"ref_51","unstructured":"Clinical and Laboratory Standards Institute (CLSI) (2025). Performance Standards for Antimicrobial Disk and Dilution Susceptibility Tests for Bacteria Isolated from Animals, Clinical and Laboratory Standards Institute. [7th ed.]."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1128\/aem.46.1.165-170.1983","article-title":"Multiple antibiotic resistance indexing of Escherichia coli to identify high-risk sources of fecal contamination of foods","volume":"46","author":"Krumperman","year":"1983","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"268","DOI":"10.1111\/j.1469-0691.2011.03570.x","article-title":"Multidrug-resistant, extensively drug-resistant and pandrug-resistant bacteria: An international expert proposal for interim standard definitions for acquired resistance","volume":"18","author":"Magiorakos","year":"2012","journal-title":"Clin. Microbiol. Infect."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"2847","DOI":"10.1093\/bioinformatics\/btw313","article-title":"Complex heatmaps reveal patterns and correlations in multidimensional genomic data","volume":"32","author":"Gu","year":"2016","journal-title":"Bioinformatics"}],"container-title":["Antibiotics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6382\/14\/7\/685\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:05:22Z","timestamp":1760033122000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6382\/14\/7\/685"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,7,6]]},"references-count":54,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2025,7]]}},"alternative-id":["antibiotics14070685"],"URL":"https:\/\/doi.org\/10.3390\/antibiotics14070685","relation":{},"ISSN":["2079-6382"],"issn-type":[{"value":"2079-6382","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,7,6]]}}}