Yeasts are not often a cause of infection. These organisms are not highly invasive. However, in patients who have some interference with defense mechanisms, yeast can gain a foothold and can cause disease. Aging changes in the skin, the vagina, and the oropharynx (the mouth and throat) offer opportunities for yeast to become infective. Diseases such as diabetes, HIV infection, and cancer may increase susceptibility to yeast infection. Treatment that interferes with immunity such as steroid therapy or cancer chemotherapy also increases susceptibility to this infection.
Yeast thrives in a warm, moist environment. Any location where skin surfaces come together for prolonged intervals are at risk. The axillae (armpits), the groin area, under the breasts, and within folds of fat are potential sites for infection with yeast.
The vagina, as it ages, loses some resistance to infection and becomes a more susceptible site for yeast infection. Although the mouth and throat are warm, moist areas, they are usually free of yeast because of the protective interaction with bacteria that compete with and suppress yeast growth. When the patient receives an antibiotic that interferes with the normal bacteria in the mouth and throat, yeast infection may become apparent. The infection may extend into the esophagus (the swallowing tube).
Important Points in Treatment
Yeast infection on the skin or in the vagina is treated with topical agents applied as a lotion or as a douche or suppository, respectively. Infection in the mouth or esophagus is treated with antiyeast drugs in a mouthwash or a troche. Dentures and mouth appliances should be cleaned carefully to prevent them from reinfecting the mouth. Systemic drugs given by mouth or injection may be used to treat severe yeast infection.