Current Aspects in the Biology, Pathogeny, and Treatment of Candida krusei, a Neglected Fungal Pathogen

Abstract

Fungal infections represent a constant and growing menace to human health, because of the emergence of new species as causative agents of diseases and the increment of antifungal drug resistance. Candidiasis is one of the most common fungal infections in humans and is associated with a high mortality rate when the fungi infect deep-seated organs. Candida krusei belongs to the group of candidiasis etiological agents, and although it is not isolated as frequently as other Candida species, the infections caused by this organism are of special relevance in the clinical setting because of its intrinsic resistance to fluconazole. Here, we offer a thorough revision of the current literature dealing with this organism and the caused disease, focusing on its biological aspects, the host-fungus interaction, the diagnosis, and the infection treatment. Of particular relevance, we provide the most recent genomic information, including the gene prediction of some putative virulence factors, like proteases, adhesins, regulators of biofilm formation and dimorphism. Moreover, C. krusei veterinary aspects and the exploration of natural products with anti-C. krusei activity are also included.

Keywords: antifungal drug; candidiasis; host-fungus interplay; immune sensing; virulence.

Figure 1

Candida krusei cell and colony morphology. (A) Yeast cells were grown in YPD broth until reach the exponential phase and then stained with calcofluor white, to label chitin. Scale bar = 10 µm. The arrowheads indicate the mother cells. (B) Cell filamentation was stimulated in RPMI medium incubated at 37°C. Scale bar = 20 µm. (C) A C. krusei colony grown on a YPD plate. Scale bar = 5.0 mm. Images from panels A and B were taken with a Zeiss Axioscope-40 microscope and an Axiocam MRc camera.