While Candida species are the most common cause of invasive fungal diseases, there are many other rare non-Candida yeast that can cause serious infections. Among non‐Candida yeast, Cryptococcus is the most common fungal pathogen that causes community‐acquired invasive fungal disease. This pathogen is particularly concerning because of its intrinsic resistance to echinocandins, a commonly utilized class of antifungal agents. Cryptococcosis initially affects the lungs or sinuses, but can disseminate to other parts of the body, including but not limited to the central nervous system and skin. In recent years there has been an increasing recognition of emergence of rare yeast genera such as Trichosporon and Rhodotorula causing invasive fungal diseases. These pathogens are of major concern because of their potential to have resistance to one or more antifungal agents. While patients that are considered immune competent can get non-Candida yeast infections, they are still more common in immunocompromised patients such as those receiving chemotherapy for cancer, underdoing bone marrow transplantation or solid organ transplantation, or those with an underlying primary immune deficiency. These infections can start as a primary blood infection, lung infection or skin infection and then disseminate to other organs. Occasionally, they will reactivate after initial effective treatment.
What are non‐Candida yeast infections?
Among human fungal pathogens, Candida species are the most common yeast that cause bloodstream infections. Among non‐Candida yeast, Cryptococcus is the most common fungal pathogen that causes community‐acquired invasive fungal disease. In addition, other rare yeast species such as Trichosporon, Rhodotorula, Geotrichum, and Magnusiomyces are increasingly recognized genera of yeast that can cause infection in immunocompromised hosts. These pathogens pose a major threat because of their low susceptibility and potential to develop resistance to one or more antifungal agents.
Who gets non‐Candida yeast infections?
Conditions in which the host immune system is suppressed are associated with infection, including:
- Iatrogenic immunosuppression (e.g., chemotherapy for cancer, corticosteroid use)
- Primary immune deficiency
- Hematopoietic cell and solid organ transplant recipients
What causes non‐Candida yeast infections?
These fungi live in common environmental habitats, and they are frequent colonizers of human skin and mucosal surfaces. Cryptococcosis is acquired through inhalation of spores in the environment including soil, bird excreta and decaying wood. Infection initially affects the lungs, but can disseminate to other parts of the body, including the central nervous system, skin, prostate and eyes. Cryptococcus spp. can establish latent infection in alveolar macrophages, which can persist asymptomatically. Host immunosuppression can allow the fungi to disseminate and reactivate infection.
How are non‐Candida yeast infections diagnosed?
Diagnosing non‐Candida yeast infections involves initial microscopic examination to spot yeast forms, but for specific identification a fungal culture is key, followed by biochemical tests or molecular methods to pinpoint the exact species and determine antifungal susceptibility, crucial because these species often resist standard treatments.
What is the treatment for non‐Candida yeast infections?
Antifungal treatment is dependent on the genus of yeast that is identified. While most of these rare yeast have at least one option for treatment, some are found to be multidrug resistant which can complicate management strategies.