Aromas&Sentidos (70)-2

Vapor-Phase of Essential Oils as a Promising Solution to Prevent Candida Vaginal Biofilms Caused by Antifungal Resistant Strains

Vulvovaginal candidiasis (VVC) is a disease with high incidence, a huge
impact on the quality of life and health of women, and which represents a great challenge to treat.
The growing need to apply antifungal intensive therapies have contributed to an emergence of
drug-resistant Candida strains. Thus, effective therapeutic options, to meet the antifungal-resistance
challenge and to control high resilient biofilms, are urgently needed. This study aimed to investigate
the antifungal activity of essentials oils (EOs) on drug-resistant Candida vaginal isolates. Method:
Therefore, the antimicrobial effect of tea tree, niaouli, white thyme, and cajeput EOs on the planktonic
growth of Candida isolates was initially evaluated by an agar disc diffusion method. Then, the
vapor-phase effect of tea tree EO (VP-TTEO) on biofilm formation and on pre-formed biofilms was
evaluated by crystal violet staining, XTT reduction assay, colony forming units’ enumeration, and
scanning electron microscopy. Results: The results revealed high antifungal activity of EOs against
drug-resistant Candida isolates. Additionally, the VP-TTEO showed a significant inhibitory effect
on the biofilm formation of all tested isolates and was able to provoke an expressive reduction in
mature Candida albicans biofilms. Conclusions: Overall, this study suggests that the VP-EO may be a
promising solution that is able to prevent biofilm-related VVC caused by antifungal-resistant strains.

Keywords: vulvovaginal candidiasis; biofilm; antifungal resistance; alternative therapies; essential
oil; vapor-phase; phytotherapeutic application

Received: 4 August 2022; Accepted: 26 August 2022; Published: 29 August 2022

Aromas&Sentidos (70)-2

Essential Oils as a Good Weapon against Drug-Resistant Candida auris

Essential Oils as a Good Weapon against Drug-Resistant Candida auris

Candida auris is a recently found Candida species, mainly associated with nosocomial outbreaks in intensive care hospital settings, and unlike other Candida species, it can be transmitted through person-to-person or by contact with surfaces. C. auris is described as resistant to first-line antifungals and, consequently, associated with high mortality. Nowadays, essential oils (EOs) are known to be effective against fungal and bacterial infections. This work aimed to evaluate the effect of four EOs (tea tree, niaouli, white thyme and cajeput) against C. auris. The EO’s effect on C. auris planktonic growth was evaluated by the minimum inhibitory concentration determination and by the agar disc diffusion method. Then, the same effect was evaluated on biofilm by colony-forming units’ enumeration. The results showed that EOs were able to inhibit the C. auris planktonic growth, with an MIC50 between 0.78 and 1.56% and halos of 20–21 mm for white thyme and tea tree and 13–14 mm for cajeput and niaouli. In addition, the EOs were also able to completely inhibit biofilm formation. Moreover, white thyme and cajeput completely eradicate pre-formed biofilms, while tea tree and niaouli significantly reduce it. Thus, this work demonstrates that EOs are a possible therapeutic alternative and a future perspective for the hard fight against C. auris.

Key words:

Essential Oils as a Good Weapon against Drug-Resistant Candida auris, Candida auris; biofilm; resistant species; natural therapy; phytotherapeutic applications; essential oils

Received 1 June 2021; Accepted 16 July 2022; Published 20 July 2022 

Aromas&Sentidos (70)-2

Comparing the effect of Thymus spp. essential oils on Candida auris

Candida auris is an emergent yeast pathogen responsible for many invasive fungal infections due to its multidrug- resistant character and its huge transmission ability. Essential oils (EOs) obtained from several aromatic plants have been regarded as an alternative treatment upon to fungal infections. For example, Thymus spp. are known by their antifungal effect due to the presence of some volatile compounds in their EOs, such as carvacrol, thymol, linalool and γ-terpinene. So, the main goal of this work was to compare the effect of several EOs from Thymus spp. on C. auris biofilm.

The antifungal activity of Thymus vulgaris, Thymus zygis, Thymus satureioides and Thymus mastichina against planktonic cells of C. auris NCPF 8971 was assessed by agar disk diffusion method. The effect of these EOs with direct or vapour phases on preformed biofilms was evaluated by colony-forming units’ enumeration. Importantly it was noticed a completely different range of action between the EOs from the same genus. While T. vulgaris showed the biggest antifungal effect with a halo of 59.75 ± 15.75 mm, T. mastichina for the other side, presented a halo of 13.13 ± 1.36 mm, showing a very low activity. In addition, the direct application of T. vulgaris and T. zygis EOs demonstrated higher antifungal activity against C. auris biofilms than vapour phase application. However, T. vulgaris also showed significant action in the vapour phase mode. The chemical composition of Thymus EOs was analysed by GC and GC-MS, and was demonstrated that they have different chemical profiles, namely in the amount of phenolic compounds, which justify the different antifungal actions.

In conclusion, T. vulgaris and T. zygis oils, can be pointed out as a great contribution to the treatment of C. auris infections, being promising alternatives to conventional therapy. However, the efficiency of the EOs differs substantially between the four species of Thymus. Therefore, the selection of natural therapies should always have in account EOs composition.

Key words: Candida auris Essential oils Thymus spp. Antifungal activity Vapour phas 

Received 17 November 2021; Received in revised form 2 February 2022; Accepted 6 February 2022 

Available online 12 February 2022