In vitro activity of essential oils against microbial isolates from otitis externa cases in dogs

Abstract

Despite the number of studies focused on the potential use of essential oils (EOs) as an alternative to conventional treatments of canine external otitis, there is controversy about their antimicrobial activity which could be explained by differences in technical or biological aspects. This study focuses on the antimicrobial activity of three single EO compounds (thymol, cinnamaldehyde and carvacrol) and two EOs (clove and oregano) against clinical isolates recovered from canine otitis externa cases (14 bacterial isolates belonging to five different genera and six Malassezia pachydermatis isolates). All compounds showed activity and cinnamaldehyde exhibited the highest bactericidal and fungicidal activity. The susceptibility was lower among bacterial isolates than fungal isolates, being this difference more evident for Gram-positive bacteria. No relationship between antibiotic multi-resistant profile and susceptibility to compounds was observed. To sum up, our results provide appropriate information about appropriate concentrations of promising candidates for the topic treatment of canine otitis.

Graphical Abstract

Keywords:

• Essential oils
• minimum inhibitory concentration
• minimum bactericidal concentration
• minimum fungicidal concentration
• otitis externa
• dog

Disclosure statement

The authors declare no competing financial interests.

Additional information

Funding

Manuel Gómez-García was supported by grant from Junta de Castilla y León co-financed by the European Social Fund (LE131-18). Héctor Puente (FPU17/00466) and Óscar Mencía-Ares (FPU16/03485) were supported by the Spanish Ministry of Education. Héctor Argüello was supported by the Spanish Ministry of Education under the programme Beatriz Galindo (BEAGAL-18-106).