Adaptation of candida albicans for growth within the host

Abstract

One of the most important attributes of microorganisms is their ability to biologically adapt to every environment on earth. Microorganisms possess sophisticated signaling systems that enable them to sense and respond to environmental changes and challenges. Typically, this response results in morphological, physiological and even genetic differentiations. The genetic information associated with a microbe is capable of alterations which are sometimes reversible, and disappearing when the particular pressure is lifted. Other alterations are maintained and can even be passed on to succeeding generations of bacteria. This fact may well indicate that the structure can be modified to maintain function under environmental stress. Candida albicans, commonly found as a component of the normal flora of humans, residing in the gastrointestinal tract, in the genitourinary tract and on the skin, is the most common opportunistic human pathogen. The yeast is a harmless commensal in most healthy people, but it causes superficial as well as life-threatening systemic infections in immunocompromised patients. The ability of C. albicans to be virulent depends completely on its yeast-to-hyphae switch where the organism changes from a unicellular yeast form to a multicellular hyphal form. This switch may likely be induced by environmental conditions like temperature, pH and nutrients. This chapter presents the regulatory adaptation mechanisms that make C. albicans the most successful fungal pathogen of humans.