Canine Pyoderma and Otitis Externa: A Retrospective Analysis of Multidrug-Resistant Bacterial Carriage in Hong Kong

<b>Background</b>: Canine pyoderma and otitis externa are prevalent bacterial skin infections in veterinary practice, frequently complicated by the emergence of multidrug-resistant (MDR) pathogens. <b>Objectives:</b> To investigate the frequency, antimicrobial resistance (AMR...

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Main Authors: Wing Yu Chan, Stefan Hobi, Andrew Ferguson, Ibrahim Elsohaby
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Antibiotics
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Online Access:https://www.mdpi.com/2079-6382/14/7/685
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author Wing Yu Chan
Stefan Hobi
Andrew Ferguson
Ibrahim Elsohaby
author_facet Wing Yu Chan
Stefan Hobi
Andrew Ferguson
Ibrahim Elsohaby
author_sort Wing Yu Chan
collection DOAJ
description <b>Background</b>: Canine pyoderma and otitis externa are prevalent bacterial skin infections in veterinary practice, frequently complicated by the emergence of multidrug-resistant (MDR) pathogens. <b>Objectives:</b> To investigate the frequency, antimicrobial resistance (AMR) profiles, and frequency of MDR bacterial isolates from dogs with pyoderma or otitis externa in Hong Kong. <b>Methods</b>: A retrospective study of bacterial isolates from 215 clinical samples collected from dogs presenting with pyoderma (<i>n</i> = 63) or otitis externa (<i>n</i> = 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. <b>Results</b>: <i>Staphylococcus</i> spp., particularly <i>S. pseudintermedius</i>, were the most commonly isolated species, followed by <i>Pseudomonas</i> spp. and <i>Proteus</i> 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–clavulanate, 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). <b>Conclusions</b>: 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.
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spelling doaj-art-1bbae821cd4f4a8199dcd3365c249f692025-08-20T03:55:48ZengMDPI AGAntibiotics2079-63822025-07-0114768510.3390/antibiotics14070685Canine Pyoderma and Otitis Externa: A Retrospective Analysis of Multidrug-Resistant Bacterial Carriage in Hong KongWing Yu Chan0Stefan Hobi1Andrew Ferguson2Ibrahim Elsohaby3Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong SAR 999077, ChinaDepartment of Veterinary Clinical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong SAR 999077, ChinaCityU Veterinary Diagnostic Laboratory Co., Ltd., City University of Hong Kong, Hong Kong SAR 999077, ChinaDepartment of Infectious Diseases and Public Health, Jockey Club of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong SAR 999077, China<b>Background</b>: Canine pyoderma and otitis externa are prevalent bacterial skin infections in veterinary practice, frequently complicated by the emergence of multidrug-resistant (MDR) pathogens. <b>Objectives:</b> To investigate the frequency, antimicrobial resistance (AMR) profiles, and frequency of MDR bacterial isolates from dogs with pyoderma or otitis externa in Hong Kong. <b>Methods</b>: A retrospective study of bacterial isolates from 215 clinical samples collected from dogs presenting with pyoderma (<i>n</i> = 63) or otitis externa (<i>n</i> = 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. <b>Results</b>: <i>Staphylococcus</i> spp., particularly <i>S. pseudintermedius</i>, were the most commonly isolated species, followed by <i>Pseudomonas</i> spp. and <i>Proteus</i> 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–clavulanate, 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). <b>Conclusions</b>: 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.https://www.mdpi.com/2079-6382/14/7/685antimicrobial susceptibilityMRSPcaninemultidrug resistanceotitis externapyoderma
spellingShingle Wing Yu Chan
Stefan Hobi
Andrew Ferguson
Ibrahim Elsohaby
Canine Pyoderma and Otitis Externa: A Retrospective Analysis of Multidrug-Resistant Bacterial Carriage in Hong Kong
Antibiotics
antimicrobial susceptibility
MRSP
canine
multidrug resistance
otitis externa
pyoderma
title Canine Pyoderma and Otitis Externa: A Retrospective Analysis of Multidrug-Resistant Bacterial Carriage in Hong Kong
title_full Canine Pyoderma and Otitis Externa: A Retrospective Analysis of Multidrug-Resistant Bacterial Carriage in Hong Kong
title_fullStr Canine Pyoderma and Otitis Externa: A Retrospective Analysis of Multidrug-Resistant Bacterial Carriage in Hong Kong
title_full_unstemmed Canine Pyoderma and Otitis Externa: A Retrospective Analysis of Multidrug-Resistant Bacterial Carriage in Hong Kong
title_short Canine Pyoderma and Otitis Externa: A Retrospective Analysis of Multidrug-Resistant Bacterial Carriage in Hong Kong
title_sort canine pyoderma and otitis externa a retrospective analysis of multidrug resistant bacterial carriage in hong kong
topic antimicrobial susceptibility
MRSP
canine
multidrug resistance
otitis externa
pyoderma
url https://www.mdpi.com/2079-6382/14/7/685
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