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Antimicrobial activity of thyme oil, oregano oil, thymol and carvacrol against sensitive and resistant microbial isolates from dogs with otitis externa.
Vet Dermatol. 2019 Dec; 30(6):524-e159.VD

Abstract

BACKGROUND

Multidrug-resistant pathogens present a major global challenge in antimicrobial therapy and frequently complicate otitis externa in dogs.

HYPOTHESIS/OBJECTIVES

In vitro efficacy of oregano oil, thyme oil and their main phenolic constituents against bacterial and fungal isolates associated with canine otitis externa were investigated. It was hypothesized that the main phenolic components would have greater antimicrobial activity compared to the relative essential oil.

METHODS AND MATERIALS

Antimicrobial susceptibility testing was performed using broth microdilution with spot-plating technique to determine minimum inhibitory and bactericidal/fungicidal concentrations (MICs, MBCs and MFCs). A time-kill kinetics assay was performed to confirm the bactericidal and fungicidal activity of the oils and their phenolic constituents. One hundred bacterial and fungal isolates, including meticillin-susceptible Staphylococcus pseudintermedius (n = 10), meticillin-resistant S. pseudintermedius (n = 10), β-haemolytic Streptococcus spp. (n = 20), Pseudomonas aeruginosa (n = 20; including 10 isolates resistant to one or two antimicrobials), Proteus mirabilis (n = 20) and Malassezia pachydermatis (n = 20) from dogs with otitis externa were used.

RESULTS

Oregano oil, thyme oil, carvacrol and thymol exhibited antibacterial activity against all bacterial and fungal isolates tested. MIC90 values ranged from 0.015 to 0.03% (146-292 μg/mL) for the Gram-positive bacteria and P. mirabilis. For P. aeruginosa and M. pachydermatis, MIC90 values ranged from 0.09 to 0.25% (800-2,292 μg/mL).

CONCLUSIONS AND CLINICAL SIGNIFICANCE

Oregano oil, thyme oil, carvacrol and thymol showed good in vitro bactericidal and fungicidal activity against 100 isolates from dogs with otitis externa, including some highly drug-resistant isolates. These essential oils and their main phenolic constituents have the potential to be further investigated in vivo for the treatment of canine otitis externa.

Authors+Show Affiliations

School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, 5000, Australia.School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, 5000, Australia. Australian Centre for Antimicrobial Resistance Ecology, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy Campus, South Australia, 5371, Australia.Australian Centre for Antimicrobial Resistance Ecology, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy Campus, South Australia, 5371, Australia.Australian Centre for Antimicrobial Resistance Ecology, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy Campus, South Australia, 5371, Australia.School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, 5000, Australia.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31566822

Citation

Sim, Jowenna Xiao Feng, et al. "Antimicrobial Activity of Thyme Oil, Oregano Oil, Thymol and Carvacrol Against Sensitive and Resistant Microbial Isolates From Dogs With Otitis Externa." Veterinary Dermatology, vol. 30, no. 6, 2019, pp. 524-e159.
Sim JXF, Khazandi M, Chan WY, et al. Antimicrobial activity of thyme oil, oregano oil, thymol and carvacrol against sensitive and resistant microbial isolates from dogs with otitis externa. Vet Dermatol. 2019;30(6):524-e159.
Sim, J. X. F., Khazandi, M., Chan, W. Y., Trott, D. J., & Deo, P. (2019). Antimicrobial activity of thyme oil, oregano oil, thymol and carvacrol against sensitive and resistant microbial isolates from dogs with otitis externa. Veterinary Dermatology, 30(6), 524-e159. https://doi.org/10.1111/vde.12794
Sim JXF, et al. Antimicrobial Activity of Thyme Oil, Oregano Oil, Thymol and Carvacrol Against Sensitive and Resistant Microbial Isolates From Dogs With Otitis Externa. Vet Dermatol. 2019;30(6):524-e159. PubMed PMID: 31566822.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Antimicrobial activity of thyme oil, oregano oil, thymol and carvacrol against sensitive and resistant microbial isolates from dogs with otitis externa. AU - Sim,Jowenna Xiao Feng, AU - Khazandi,Manouchehr, AU - Chan,Wei Yee, AU - Trott,Darren J, AU - Deo,Permal, Y1 - 2019/09/30/ PY - 2019/08/05/accepted PY - 2019/10/1/pubmed PY - 2020/4/10/medline PY - 2019/10/1/entrez SP - 524 EP - e159 JF - Veterinary dermatology JO - Vet. Dermatol. VL - 30 IS - 6 N2 - BACKGROUND: Multidrug-resistant pathogens present a major global challenge in antimicrobial therapy and frequently complicate otitis externa in dogs. HYPOTHESIS/OBJECTIVES: In vitro efficacy of oregano oil, thyme oil and their main phenolic constituents against bacterial and fungal isolates associated with canine otitis externa were investigated. It was hypothesized that the main phenolic components would have greater antimicrobial activity compared to the relative essential oil. METHODS AND MATERIALS: Antimicrobial susceptibility testing was performed using broth microdilution with spot-plating technique to determine minimum inhibitory and bactericidal/fungicidal concentrations (MICs, MBCs and MFCs). A time-kill kinetics assay was performed to confirm the bactericidal and fungicidal activity of the oils and their phenolic constituents. One hundred bacterial and fungal isolates, including meticillin-susceptible Staphylococcus pseudintermedius (n = 10), meticillin-resistant S. pseudintermedius (n = 10), β-haemolytic Streptococcus spp. (n = 20), Pseudomonas aeruginosa (n = 20; including 10 isolates resistant to one or two antimicrobials), Proteus mirabilis (n = 20) and Malassezia pachydermatis (n = 20) from dogs with otitis externa were used. RESULTS: Oregano oil, thyme oil, carvacrol and thymol exhibited antibacterial activity against all bacterial and fungal isolates tested. MIC90 values ranged from 0.015 to 0.03% (146-292 μg/mL) for the Gram-positive bacteria and P. mirabilis. For P. aeruginosa and M. pachydermatis, MIC90 values ranged from 0.09 to 0.25% (800-2,292 μg/mL). CONCLUSIONS AND CLINICAL SIGNIFICANCE: Oregano oil, thyme oil, carvacrol and thymol showed good in vitro bactericidal and fungicidal activity against 100 isolates from dogs with otitis externa, including some highly drug-resistant isolates. These essential oils and their main phenolic constituents have the potential to be further investigated in vivo for the treatment of canine otitis externa. SN - 1365-3164 UR - https://www.unboundmedicine.com/medline/citation/31566822/Antimicrobial_activity_of_thyme_oil_oregano_oil_thymol_and_carvacrol_against_sensitive_and_resistant_microbial_isolates_from_dogs_with_otitis_externa_ L2 - https://doi.org/10.1111/vde.12794 DB - PRIME DP - Unbound Medicine ER -