Candida krusei: biology, epidemiology, pathogenicity and clinical manifestations of an emerging pathogen.

Early reports of Candida krusei in man describe the organism as a transient, infrequent isolate of minor clinical significance inhabiting the mucosal surfaces. More recently it has emerged as a notable pathogen with a spectrum of clinical manifestations such as fungaemia, endophthalmitis, arthritis and endocarditis, most of which usually occur in compromised patient groups in a nosocomial setting. The advent of human immunodeficiency virus infection and the widespread use of the newer triazole fluconazole to suppress fungal infections in these patients have contributed to a significant increase in C. krusei infection, particularly because of the high incidence of resistance of the yeast to this drug. Experimental studies have generally shown C. krusei to be less virulent than C. albicans in terms of its adherence to both epithelial and prosthetic surfaces, proteolytic potential and production of phospholipases. Furthermore, it would seem that C. krusei is significantly different from other medically important Candida spp. in its structural and metabolic features, and exhibits different behaviour patterns towards host defences, adding credence to the belief that it should be re-assigned taxonomically. An increased awareness of the pathogenic potential of this yeast coupled with the newer molecular biological approaches to its study may facilitate the continued exploration of the epidemiology and pathogenesis of C. krusei infections.