Infections Due to Candida, Cryptococcus, Other Yeasts, and Pneumocystis

Abstract

Yeast-based fungal infections have become increasingly important over several decades, paradoxically because advances in medical practice have allowed patients with chronic medical conditions to live longer and have more productive lives. Many of these yeast infections are superficial in nature, such as thrush and candidal vaginitis among persons treated with antibiotics or with short courses of steroids. A minority of the yeast infections are associated with significant morbidity and mortality, generally among debilitated or otherwise immunosuppressed patients who have survived major surgeries or extensive chemotherapy regimens. These opportunistic yeast pathogens may originate as human commensals (e.g., Candida albicans) or have an environmental reservoir (e.g., Cryptococcus neoformans). Opportunistic Pneumocystis infections are inhaled. Knowledge of the host characteristics associated with specific infections will allow high suspicion for the type of yeast infection that may be occurring. Standard methods for making a diagnosis have included antigen testing, culture, and cytology. Newer methods for making the diagnosis include nucleic acid testing and nanotechnology. There are three general classes of antifungal agents. Treatment with antifungal agents for the most serious of these infections requires source control for cure. In addition, correction of predisposing conditions will also assist with prevention of recurrence. Immunocompromised patients require either prophylaxis or early empirical treatment during high-risk periods. This review contains 1 figure, 4 tables, and 74 references. Key words: Candida, Candidiasis, Cryptococcus, Malassezia, Trichosporon, Pneumocystis