The effect of Rosmarinus officinalis essential oil on germ tube formation in Candida dubliniensis recovered from denture users

Abstract

Candida dubliniensis is an emerging pathogenic yeast that is closely related to C. albicans and colonizes or infects the oral cavities of denture users. Similar to C. albicans, C. dubliniensis produces germ tubes as a major virulence factor. Due to the scarcity of data demonstrating that natural products have anti-C. dubliniensis activity, the objective of this study was to evaluate the effect of an essential oil from Rosmarinus officinalis on C. dubliniensis germ tube formation. Six isolates of C. dubliniensis were recovered from the oral cavities (n = 5/denture base and n = 1/palatal mucosa) of six denture users either with (n = 4) or without (n = 2) stomatitis. Germ tube formation was induced in Sabouraud dextrose broth containing 10% fetal bovine serum in the presence (test) or absence (control) of 4% R. officinalis essential oil. The complete inhibition of germ tube formation for all of the tested isolates of C. dubliniensis was observed (p = 0.004). Our results demonstrate the potent anti-C. dubliniensis effect of R. officinalis essential oil, indicating the need to further investigate the pharmaceutical use of R. officinalis essential oil, particularly as it impacts the colonization of denture resin and stomatitis.