Peer-reviewed veterinary case report
Which ear cleaner works best against dog ear infection germs?
By Savaliya, Bhumika F et al.·Published in Veterinary dermatology·2025·School of Animal and Veterinary Sciences, Australia·View original on PubMed →
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Original publication title: Comparison of the in vitro antibiofilm activities of otic cleansers against canine otitis externa pathogens.
- Species:
- dog
Plain-English summary
A study found that a specific ear cleaner called PHMB-EDTA can effectively break down biofilms produced by bacteria that cause ear infections in dogs. These infections, known as canine otitis externa, can be tough to treat because the bacteria often resist standard medications. The research showed that PHMB-EDTA worked well at low concentrations against various bacteria involved in these infections. This means it could be a helpful addition to other treatments your vet might recommend for your dog's ear infection.
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Abstract
BACKGROUND: Biofilm production by canine otitis externa (COE) pathogens and resistance development to multiple antimicrobials are commonly reported problems in veterinary practice. The use of adjuvants to disrupt biofilms may be a viable adjunctive therapy. HYPOTHESIS/OBJECTIVES: To compare the in vitro antibiofilm activity against COE pathogens of three otic cleansers: PHMB-EDTA (poly [hexamethylene] biguanide hydrochloride and disodium edetate), N-acetylcysteine (NAC) and Triz-EDTA. ANIMALS/ISOLATES: Thirty isolates of each species, including Staphylococcus pseudintermedius, Pseudomonas aeruginosa, Streptococcus canis, Proteus mirabilis, Escherichia coli, and Malassezia pachydermatis, were collected from COE cases and stored at -80°C until tested. METHODS AND MATERIALS: Biofilm production was determined by Congo-red agar and microtitre plate-assay methods. Ten of the best biofilm-producing isolates per species were selected to determine minimum biofilm eradication concentration (MBEC) values. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were determined to compare MBEC/MIC and MBEC/MBC. RESULTS: PHMB-EDTA possessed antibiofilm activity at low concentrations (MBEC range 3.9/2.3-500/300 μg/mL) against all tested COE pathogens. NAC demonstrated antibiofilm activity for all tested bacterial COE pathogens (MBEC range 4,925-19,700 μg/mL); however, most M. pachydermatis isolates exhibited MBEC values >20,000 μg/mL. Triz/EDTA at the highest concentration tested (3,025/19,520 μg/mL) did not demonstrate antibiofilm activity against most COE pathogens except for S. canis (94.5/610 μg/mL). CONCLUSIONS AND CLINICAL RELEVANCE: PHMB-EDTA had intrinsic antibiofilm activity at low concentrations against all COE pathogens. Therefore, it is likely to be a very effective adjuvant when used in conjunction with other antimicrobials for the treatment of COE caused by biofilm-producing pathogens.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/39976169/