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Type: Journal article
Title: In vitro antimicrobial activity of seven adjuvants against common pathogens associated with canine otitis externa
Author: Chan, W.
Khazandi, M.
Hickey, E.
Page, S.
Trott, D.
Hill, P.
Citation: Veterinary Dermatology, 2019; 30(2):133
Publisher: Wiley
Issue Date: 2019
ISSN: 0959-4493
Statement of
Wei Yee Chan, Manouchehr Khazandi, Elizabeth E. Hickey, Stephen W. Page Darren J. Trott, Peter B. Hill
Abstract: BACKGROUND:An antibiotic adjuvant is a chemical substance used to modify or augment the effectiveness of primary antimicrobial agents against drug-resistant micro-organisms. Its use provides an alternative approach to address the global issue of antimicrobial resistance and enhance antimicrobial stewardship. HYPOTHESIS/OBJECTIVES:To determine the antimicrobial activity of a panel of potential antimicrobial adjuvants against common pathogens associated with canine otitis externa (OE). ANIMALS/ISOLATES:A number of type strains and clinical isolates (n = 110) from canine OE were tested including Staphylococcus pseudintermedius, β-haemolytic Streptococcus spp., Pseudomonas aeruginosa, Proteus mirabilis and Malassezia pachydermatis. METHODS AND MATERIALS:Antimicrobial activities of monolaurin, monocaprin, N-acetylcysteine (NAC), polymyxin B nonapeptide, Tris-EDTA, Tris-HCL and disodium EDTA were tested using microdilution methodology according to CLSI guidelines. RESULTS:N-acetylcysteine, Tris-EDTA and disodium EDTA had antimicrobial activity against both type strains and otic pathogens. The other adjuvants tested had limited to no efficacy. NAC had a minimal inhibitory concentration (MIC) range of 2,500-10,000 μg/mL for the various organisms. Pseudomonas aeruginosa isolates were eight times more susceptible to disodium EDTA in the presence of Tris-HCL in comparison to disodium EDTA alone. Malassezia pachydermatis isolates were most susceptible to Tris-EDTA (MIC90  = 190/60 μg/mL) and disodium EDTA (MIC90  = 120 μg/mL). CONCLUSIONS AND CLINICAL RELEVANCE:N-acetylcysteine, Tris-EDTA and disodium EDTA have intrinsic antimicrobial activity and represent promising adjuvants that could be used to enhance the efficacy of existing antibiotics against Gram-negative and multidrug-resistant bacterial infections. These agents could be combined with other antimicrobial agents in a multimodal approach for mixed ear infections in dogs.
Keywords: Acetylcysteine
Rights: © 2018 ESVD and ACVD
RMID: 0030105673
DOI: 10.1111/vde.12712
Grant ID:
Appears in Collections:Animal and Veterinary Sciences publications

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