Optimum Inhibition of Amphotericin-B-Resistant <i>Candida albicans</i> Strain in Single- and Mixed-Species Biofilms by <i>Candida</i> and Non-<i>Candida</i> Terpenoids

• Main Authors: Hidaya F. Z. Touil, Kebir Boucherit, Zahia Boucherit-Otmani, Ghalia Kohder, Mohamed Madkour, Sameh S. M. Soliman
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Biomolecules
• Subjects: highly resistant <i>candida albicans</i>; mixed infection; biofilm; terpenoids; farnesol; carvacrol
• Online Access: https://www.mdpi.com/2218-273X/10/2/342

<i>Candida albicans</i> is one of the most common human fungal pathogens and represents the most important cause of opportunistic mycoses worldwide. Surgical devices including catheters are easily contaminated with <i>C. albicans</i> via its formation of drug-resistant biofilms. In this study, amphotericin-B-resistant <i>C. albicans</i> strains were isolated from surgical devices at an intensive care center. The objective of this study was to develop optimized effective inhibitory treatment of resistant <i>C. albicans</i> by terpenoids, known to be produced naturally as protective signals. Endogenously produced farnesol by <i>C. albicans</i> yeast and plant terpenoids, carvacrol, and cuminaldehyde were tested separately or in combination on amphotericin-B-resistant <i>C. albicans</i> in either single- or mixed-infections. The results showed that farnesol did not inhibit hyphae formation when associated with bacteria. Carvacrol and cuminaldehyde showed variable inhibitory effects on <i>C. albicans</i> yeast compared to hyphae formation. A combination of farnesol with carvacrol showed synergistic inhibitory activities not only on <i>C. albicans</i> yeast and hyphae, but also on biofilms formed from single- and mixed-species and at reduced doses. The combined terpenoids also showed biofilm-penetration capability. The aforementioned terpenoid combination will not only be useful in the treatment of different resistant <i>Candida</i> forms, but also in the safe prevention of biofilm formation.