Candida: Friend and Foe of Humans

Abstract

Opportunistic fungal infections pose a serious public health challenge. Candida species are the most common cause of hospital-acquired bloodstream fungal infections and are associated with a mortality rate of about 40%. Majority of these infections are caused by the yeast Candida albicans, which lives in the mouth, intestines, and urinary and reproductive tracts in healthy individuals but causes various infections in patients with weakened immune systems. C. albicans, which is multimorphic in nature, has no known terrestrial life cycle. The spectrum of diseases caused by C. albicans includes superficial infections of the skin (thrush), vagina (yeast infections), mouth (oral thrush), and life-threatening bloodstream infections (candidemia). Candidemia, which is diagnosed by fungal culture of the blood, usually results in the multiple organ failure and patient death. Candida infections commonly arise from the microflora of the patient but can spread in health-care settings due to contaminated beds, medical equipment, surfaces, and hands of health-care workers. Recent global surveillance programs have revealed significant contribution of four other species of Candida, C. glabrata, C. tropicalis, C. parapsilosis, and C. krusei, to bloodstream Candida infections. We will discuss salient features and prevalence of Candida species, the spectrum of diseases caused, and their prevention, diagnosis, and treatment in this chapter.