The Activity of Combination of Fluconazole with Ethanol Extracts of Some Medicinal Plants as Antifungals Against Some Clinical Candida species

Abstract

The global threat posed by fungal infections has escalated significantly, with an increasing number of cases linked to drug-resistant pathogens, particularly among Candida species. Combining natural compounds with conventional treatments can be a more effective and less toxic form of antifungal therapy. This study was thus, undertaken to evaluate the combined in vitro antifungal activity of fluconazole and ethanol leaf extracts of Moringa oleifera, Vernonia amygdalina and Ocimum gratissimum against some clinical Candida species. Six isolates that were resistant to three or more of the commercial antifungal drugs were selected for this study. The resistant isolates were two of each of Candida tropicalis and Candida albicans and one of each of Candida Parapsilosis and Candida krusei. Combined activity of Fluconazole and each of the plant extracts was determined using the continuous variation Checkerboard method. The results showed that out of a total of 162 combination ratios of Fluconazole with either of the plant extracts, sixty-two (38.27%) were synergistic with Fractional inhibitory concentration (FIC) index < 1.0, against the selected Candida species. None (0%) of the combination ratios had any additive (FIC index = 1.0) effect against the Candida species while the combination of the ethanol extract of M. oleifera with Fluconazole was the best as 26 (48.15%) out of the 54 combination ratios of were synergistic against the Candida species. Combination with Ocimum gratissimum was the poorest as 29 (53.7%) out of the 54 combination ratios had no activity (FIC index = 0) against the selected Candida species. However, the synergistic effects recorded in this study, suggest that the use of the ethanol extract of these plants combined with Fluconazole in the appropriate ratios against the Candida species can have very promising results in treatment, especially with regards to the resistant Candida species. This study, thus, recommends further purification of the plant extracts in order to isolate and characterize the active principles that can be used for combination studies with Fluconazole (and other azoles) against resistant Candida species.