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In vitro antimicrobial activity of seven adjuvants against common pathogens associated with canine otitis externa.
Vet Dermatol. 2019 Apr; 30(2):133-e38.VD

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.

Authors+Show Affiliations

Australian Centre for Antimicrobial Resistance Ecology, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, 5371, Australia.Australian Centre for Antimicrobial Resistance Ecology, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, 5371, Australia.Australian Centre for Antimicrobial Resistance Ecology, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, 5371, Australia.Luoda Pharma Pty. Ltd., Caringbah, NSW, 2229, Australia.Australian Centre for Antimicrobial Resistance Ecology, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, 5371, Australia.Australian Centre for Antimicrobial Resistance Ecology, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, 5371, Australia.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

30548715

Citation

Chan, Wei Yee, et al. "In Vitro Antimicrobial Activity of Seven Adjuvants Against Common Pathogens Associated With Canine Otitis Externa." Veterinary Dermatology, vol. 30, no. 2, 2019, pp. 133-e38.
Chan WY, Khazandi M, Hickey EE, et al. In vitro antimicrobial activity of seven adjuvants against common pathogens associated with canine otitis externa. Vet Dermatol. 2019;30(2):133-e38.
Chan, W. Y., Khazandi, M., Hickey, E. E., Page, S. W., Trott, D. J., & Hill, P. B. (2019). In vitro antimicrobial activity of seven adjuvants against common pathogens associated with canine otitis externa. Veterinary Dermatology, 30(2), 133-e38. https://doi.org/10.1111/vde.12712
Chan WY, et al. In Vitro Antimicrobial Activity of Seven Adjuvants Against Common Pathogens Associated With Canine Otitis Externa. Vet Dermatol. 2019;30(2):133-e38. PubMed PMID: 30548715.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - In vitro antimicrobial activity of seven adjuvants against common pathogens associated with canine otitis externa. AU - Chan,Wei Yee, AU - Khazandi,Manouchehr, AU - Hickey,Elizabeth E, AU - Page,Stephen W, AU - Trott,Darren J, AU - Hill,Peter B, Y1 - 2018/12/13/ PY - 2018/11/08/accepted PY - 2018/12/15/pubmed PY - 2019/4/2/medline PY - 2018/12/15/entrez SP - 133 EP - e38 JF - Veterinary dermatology JO - Vet. Dermatol. VL - 30 IS - 2 N2 - 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. SN - 1365-3164 UR - https://www.unboundmedicine.com/medline/citation/30548715/In_vitro_antimicrobial_activity_of_seven_adjuvants_against_common_pathogens_associated_with_canine_otitis_externa_ L2 - https://doi.org/10.1111/vde.12712 DB - PRIME DP - Unbound Medicine ER -