Antibacterial and Antifungal Activity of Essential Oils against Pathogens Responsible for Otitis Externa in Dogs and Cats

Abstract

Background: Essential oils (EOs) are recommended by some veterinarians to treat otitis externa in pets, but data about their efficacy in scientific literature are very scant. Methods: Nine commercial EOs, from roman chamomile (Anthemis nobilis L.), star anise (Illicium verum), lavender (Lavandula hybrida), litsea (Litsea cubeba (Lour.) Pers.), basil (Ocimum basilicum L.), oregano (Origanum vulgare L. subsp. hirticum), rosemary (Rosmarinus officinalis L.), clary sage (Salvia sclarea L.), and thyme (Thymus vulgaris L.) were tested against bacterial and fungal pathogens previously isolated from dogs and cats with otitis externa. In particular, the analyses were carried out against Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus pseudointermedius, Aspergillus niger, Aspergillus fumigatus, Aspergillus terreus, Candida albicans, Candida tropicalis, Trichosporon sp., and Rhodotorula sp. Results: O. vulgare and S. sclarea showed superior antibacterial activity, even if not against all the strains. Trichosporon sp., C. albicans, and A. terreus were insensitive to most Eos, while other yeasts and molds showed different degrees of sensitivity. In particular, most fungi were inhibited by O. vulgare and R. officinalis. Conclusions: The obtained results suggest that some EOs could be included in treatment as an alternative therapeutic option in bacterial otitis complicated by fungi, in association with conventional drugs.

Antimicrobial activity of thyme oil, oregano oil, thymol and carvacrol against sensitive and resistant microbial isolates from dogs with otitis externa

“…In this study, both oregano oil and thyme oil showed good antimicrobial activity against Gram‐negative and Gram‐positive bacteria as well as M. pachydermatis with MIC 90 values ranging from 0.02 to 0.25% (200–2,292 μg/mL). These results are in agreement with previous studies including oregano oil and thyme oil as potential antimicrobial agents against a broad range of bacteria; however, these studies mostly used the disk diffusion technique and presented the MIC values. In the present study, the antimicrobial activities of the essential oils and their phenolic components are reported as MIC range, MIC 50 and MIC 90 values.…”

“…Thyme oil and oregano oil, and their main component have been reported for antimicrobial activities against both bacteria and fungi . One study determined antimicrobial activity for these essential oils against microbes associated with otitis externa in animals . However, to the best of the authors’ knowledge, no study has looked at their main phenolic components against a range of common clinical otitis externa microbes, including sensitive and resistant strains.…”

Antimicrobial effects of cinnamon essential oil and cinnamaldehyde combined with EDTA against canine otitis externa pathogens

“…As demonstrated by the current increase in the transmission of antimicrobial-resistant pathogens from animals to humans, this study aimed to undertake preliminary screening of the antimicrobial activity of cinnamon oil and cinnamaldehyde against 31 strains, including ATCC strains and resistant clinical pathogens responsible for canine diseases, such as pyodermas, septicaemia, meningitis, urological infections, otitis externa and pneumoniae. (Duquette and Nuttall 2004;Lamm et al 2009;Jayanthi and Jeya 2014;Ebani et al 2017). Our results showed that both compounds exhibited promising antimicrobial activity against all pathogens tested, including bactericidal activity at their MICs except for Staphylococcus sp.…”

“…; Jayanthi and Jeya ; Ebani et al . ). Our results showed that both compounds exhibited promising antimicrobial activity against all pathogens tested, including bactericidal activity at their MICs except for Staphylococcus sp.…”

Antifungal in vitro Activity of Essential Oils against Clinical Isolates of <b><i>Malassezia pachydermatis</i></b> from Canine Ears: A Report from a Practice Laboratory

“…Thus, another positive effect of EOs in treatment could be their additional antibacterial effect. This was already shown in vitro against several bacterial veterinary isolates [34,36,48,65,66]. In addition, EOs can exhibit anti-inflammatory potential [67], which might be another positive attribute for treatment of otitis externa.…”