Information for Healthcare Professionals about Cryptococcus neoformans Infection
Depending on the virulence of the yeast strain and the immune status of the host, Cryptococcus neoformans can cause either no infection, latent infection, or symptomatic disease. Because C. neoformans enters the body through the respiratory route, infection can present as pneumonia-like illness, with symptoms such as cough, fever, chest pain, and weight loss. Pulmonary nodules and hilar lymphadenopathy may be seen on chest radiography. C. neoformans can also disseminate to the central nervous system (CNS) and cause meningoencephalitis. Symptoms of a CNS infection may include fever, headache, lethargy, and mental status changes.
Worldwide distribution in soil, decaying wood, tree hollows, and bird droppings.
C. neoformans infection is acquired through inhalation of basidiospores or desiccated yeast cells from the environment. The infection may be cleared, become latent, cause pulmonary infection, or disseminate to other parts of the body, typically the CNS.
- Culture: The gold standard for diagnosing cryptococcal infection; culture traditionally used to identify Cryptococcus from human body specimens.
- Microscopy: India Ink can be performed on Cerebrospinal fluid (CSF ) to quickly visualize Cryptococcus cells under a microscope; however, it has limited sensitivity. Histopathology for detection of narrow-based budding yeasts in tissue can also be used.
- Antigen detection: Can be used on CSF or serum. Particularly useful for rapid detection of early, asymptomatic cryptococcal infection in HIV-infected patients; higher sensitivity than microscopy or culture.
- Latex agglutination (LA)
- Enzyme immunoassay (EIA)
- Lateral flow assay (LFA)
Photomicrograph of Cryptococcus neoformans
Grocott methenamine silver (GMS) stain showing Cryptococcus in lung tissue
C. neoformans meningitis may lead to permanent neurologic damage. Mortality rate varies by geographic location, access to medical care, and immune status of the host.
Fluconazole is the recommended treatment for asymptomatic or mild to moderate pulmonary infections. For severe pulmonary or CNS infections, amphotericin B in combination with flucytosine is the preferred initial treatment; after that, patients usually need to take fluconazole for an extended time to clear the infection.
The type, dose, and duration of antifungal treatment may differ for certain groups, such as pregnant women, children, and people in resource-limited settings. Some people may also need surgery to remove fungal growths (cryptococcomas).
Please see the Infectious Diseases Society of America’s Clinical Practice Guidelines for the Management of Cryptococcal Disease [PDF – 32 pages]external icon.
The World Health Organization has also developed guidelines for the diagnosis, prevention, and management of cryptococcal disease in HIV-infected adults, adolescents, and childrenexternal icon, with a focus on resource-limited settings.
Immunocompromised persons such those with advanced HIV/AIDS (CD4<200 cells/mm), organ transplant recipients, and persons taking corticosteroids or other immunosuppressive medications are at highest risk, but otherwise healthy patients sometimes get infections as well.
In the United States, cryptococcosis is reportable in a few states. Check with your local, state, or territorial public health department for more information about disease reporting requirements and procedures in your area. Get cryptococcosis statistics.