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To detect a fungal infection, to determine which specific fungus or fungi are present, and to help guide treatment
When a healthcare practitioner suspects that you have a skin, lung, or systemic fungal infection; sometimes after treatment to monitor its effectiveness
The sample collected depends upon the suspected location(s) of the infection. Some examples include: scrapings of the skin, nail and hair samples, body fluids, blood, and/or a tissue biopsy.
None
Fungi are microbes that exist in nature as one-celled yeasts or as branching filamentous molds (also may be spelled "moulds"). Only about 20 to 25 species of fungi are common causes of infection. Fungal tests detect infections and sometimes identify the fungus and help guide treatment.
Fungal infections range from superficial skin infections to serious deep tissue, blood, lung, or systemic diseases.
Fungal tests are used to detect and identify fungi in order to diagnose infections and help guide treatment. Fungal testing typically includes a microscopic examination of the sample on a slide, sometimes using a preparation or stain to aid in detection of fungal elements. This may be sufficient to determine that the infection is due to a fungus and, with superficial infections, no further testing may be required.
However, in cases of persistent, deep, or systemic infections when a more definitive diagnosis is needed, the microscopic exam may be followed by additional tests, such as culture and susceptibility testing, antigen or antibody tests, or molecular tests that detect fungal genetic material.
The sample collected depends upon the suspected location(s) of the infection. For superficial infections, the sample may include scrapings of the skin, clipped or shaved nail or hair, vaginal secretions collected with a swab, or a urine sample. For deeper tissue, organ, or systemic infections, the sample may involve the collection of urine, blood from a vein, sputum from the lungs, bone marrow, and/or the collection of a tissue biopsy. If meningitis is suspected, a sample of cerebrospinal fluid is collected.
No test preparation is needed.
Fungal tests are used to help detect and diagnose a fungal infection, to help guide treatment, and/or to monitor the effectiveness of treatment.
The following tables summarize uses of various fungal tests:
Test Name | Sample Type(s) | Description | Uses | Time for Results |
---|---|---|---|---|
KOH prep (potassium hydroxide solution) |
Skin scrapings, hair or nail clippings, tissue, vaginal swab, body fluids, sputum | The sample is placed on a slide and the chemical solution dissolves non-fungal elements; reveals yeast cells and fungal hyphae (branching filaments) on a microscope slide; examined by a healthcare practitioner or trained laboratorian. | Primary screening tool; detects fungi but does not tell what specific fungus is present. | Rapid |
Calcofluor white stain | Skin scrapings, hair or nail clippings, vaginal swab, body fluids, sputum | Stain binds to fungal elements in a sample and fluoresces (glows) under ultraviolet light; allows visualization on microscope slide; more sensitive means of visualizing fungi. | Detects fungi but does not tell what specific fungus is present. | Rapid |
Fungal culture | Skin, nail, hair, body fluids, tissue, vaginal swab, sputum, blood | A sample is placed on or into nutrient media and incubated to grow any fungi present in sample. | Primary tool to diagnose a fungal infection; grows fungi for identification tests and subsequent susceptibility testing. | Weeks |
When a more definitive diagnosis is needed, as in cases of persistent, deep, or systemic infections, more extensive testing may be required to identify which fungus is causing the infection and help determine the treatment that may be most effective. This usually involves a combination of the tests mentioned above plus the following tests:
Test Name | Sample Type(s) | Description | Uses | Time for Results |
---|---|---|---|---|
Susceptibility testing | Sample of fungus isolated in culture | Follow-up to fungal culture; when a pathogenic fungus has been identified, susceptibility testing is sometimes ordered to determine the most effective antifungal agent(s) to use. | Guide treatment | Days to weeks after culture |
Antigen testing | Blood, urine, CSF, body fluids | Detects proteins associated with a specific fungus. This type of test is available for a variety of fungi. | Diagnose infection by specific fungus | Day(s); rapid tests are available for some fungi (e.g., Cryptococcus, Histoplasma species) |
Antibody testing | Blood, CSF, body fluids | Detects immune response to a specific fungus; may be ordered on a single sample or on acute and convalescent samples collected 2 to 3 weeks apart. | Diagnose current or recent infection by specific fungus; monitor treatment | Day(s) or weeks |
Molecular tests for DNA, RNA | Sample of fungus isolated in culture, blood, CSF, body fluids | Detects genetic material of a specific fungus. | Detects some fungi; not yet widely available, some in research settings only | Days to weeks |
Fungal tests are ordered whenever a healthcare practitioner suspects that a person's signs and symptoms are due to a fungal infection. Many signs and symptoms of fungal infections are similar to those caused by bacteria and/or viruses, and fungal tests are often ordered when it is not clear what is causing the condition.
For superficial infections, tests may be ordered when symptoms involving skin, nails, or mucous membranes appear, for example:
Deep and systemic fungal infections may cause a variety of symptoms depending on the part of the body that is affected. Some examples include:
Fungal tests may also be ordered after or periodically during treatment to evaluate its effectiveness or to monitor for infection recurrence.
Interpretation of fungal tests and examinations of slides and cultures often require experience in the study of fungi. Results must be carefully considered, along with signs and symptoms as well as medical history, and sometimes travel history, of the person tested.
Superficial Infections
Many superficial fungal infections are diagnosed based on a physical examination. In addition to general symptoms, many skin infections have characteristic signs (such as the appearance of infected nails) and typical locations on the body (such as athlete's foot between the toes). A clinical evaluation cannot, however, definitively tell the healthcare practitioner which microbe is causing a fungal infection. Sometimes a microscopic examination or culture of a sample may be useful in detecting and confirming a fungal infection and may help guide treatment.
Some examples of superficial infections include:
Deep Tissue, Lung, Blood, and Systemic Infections
In cases of persistent, deep, or systemic infections, a definitive diagnosis is needed and more extensive testing may be required to identify which fungus is causing the infection and to guide treatment. This usually involves a combination of several tests that may be performed on samples of sputum or tissue retrieved from the lungs, blood, urine, or spinal fluid. Examples of some serious fungal infections that may be require extensive testing include:
For more on these, see the article on Fungal Infections.
In general, a negative test result means that there is no fungal infection present and symptoms are likely due to another cause. A negative test after a person has been treated for a fungal infection means that the therapy has been successful.
Positive results generally indicate that a fungus is present and sometimes identify the type causing an infection:
If a fungus that is causing an infection is not present in sufficient amount in a sample, a test to detect and/or identify the fungus may be falsely negative.
For antibody testing, some infected individuals with weakened immune systems may not produce antibodies as expected.
Fungal infections must frequently be distinguished from infections caused by other microbes, such as bacteria. In some cases, an infection may have both bacteria and fungi present. Tests that may be used to identify or rule out other causes include:
Fungi thrive in moist environments, such as surfaces in and around public swimming pools and gym locker rooms, inside sweaty shoes and socks, in skin folds, and wherever skin is kept moist by constrictive clothing. Fungal skin infections can be minimized by wearing flip-flops or sandals when walking around the pool or locker room, by changing socks and underwear at least once a day, drying out shoes, and keeping moist areas of the body clean and dry.
Some fungi are found in distinct geographical regions, such in the southwestern U.S. or midwestern U.S. If you have been around excavation or spelunking in caves, you may have been exposed to fungal spores. This can be true, even if travel was not recent. Lung infections caused by some fungi may emerge months to even years after exposure. (For more on this, see Travelers' Diseases.)
Many of the signs and symptoms associated with fungal lung infections could also be due to a tuberculosis infection. Generally, a healthcare practitioner would order tuberculosis testing (such as an AFB smear and culture) to rule out infection with Mycobacterium tuberculosis (the bacteria that cause tuberculosis) as the cause of your symptoms. The organisms that cause both fungal lung infections and tuberculosis tend to be slow-growing, both in the body and in the laboratory.
Some may, but most persist without treatment. Lung and systemic infections may grow progressively worse and cause permanent tissue and organ damage even when symptoms are not severe. Some deep infections are almost uniformly fatal without treatment.
Yes. Even if you start feeling better in a short period of time, you should follow your healthcare provider's recommendations. While yeast infections may resolve within a few days to weeks, some fungal infections may require months or even years of consistent treatment.
Sources Used in Current Review
Centers for Disease Control and Prevention (December 2, 2014 updated). Types of Fungal Diseases. Available online at http://www.cdc.gov/fungal/diseases/index.html. Accessed August 27, 2016.
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American Thoracic Society (October 2013 updated). Candida Infection of the Bloodstream– Candidemia. Available online at http://www.thoracic.org/patients/patient-resources/resources/candidemia.pdf. Accessed September 5, 2016.
American Thoracic Society (October 2013 updated). Coccidiodomycosis. Available online at http://www.thoracic.org/patients/patient-resources/resources/coccidioidomycosis.pdf. Accessed September 5, 2016.
American Thoracic Society (October 2013 updated). Histoplasmosis. Available online at http://www.thoracic.org/patients/patient-resources/resources/histoplasmosis.pdf. Accessed September 5, 2016.
Mayo Medical Laboratories. Aspergillus (Galactomannan) Antigen, Serum. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/84356. Accessed September 5, 2016.
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Centers for Disease Control and Prevention (December 28, 2015 updated.) Blastomycosis. Available online at http://www.cdc.gov/fungal/diseases/blastomycosis/index.html. Accessed August 27, 2016.
Centers for Disease Control and Prevention (June 12, 2015 updated.) Candidiasis. Available online at http://www.cdc.gov/fungal/diseases/candidiasis/index.html. Accessed August 27, 2016.
Centers for Disease Control and Prevention (February 13, 2014 updated.) Genital/Vulvovagial Candidiasis (VVC). Available online at http://www.cdc.gov/fungal/diseases/candidiasis/genital/index.html. Accessed August 27, 2016.
Centers for Disease Control and Prevention (June 12, 2015 updated). Invasive Candidiasis. Available online at http://www.cdc.gov/fungal/diseases/candidiasis/invasive/index.html. Accessed August 27, 2016.
Centers for Disease Control and Prevention (June 29, 2015 updated). Valley Fever (Coccidioidomycosis). Available online at http://www.cdc.gov/fungal/diseases/coccidioidomycosis/index.html. Accessed August 27, 2016.
Centers for Disease Control and Prevention (November 28, 2015 updated). C. neoformans Infection. Available online at http://www.cdc.gov/fungal/diseases/cryptococcosis-neoformans/index.html. Accessed August 27, 2016.
Centers for Disease Control and Prevention (December 16, 2015 updated). C. gatti Infection. Available online at http://www.cdc.gov/fungal/diseases/cryptococcosis-gattii/index.html. Accessed August 27, 2016.
Centers for Disease Control and Prevention (November 21, 2015 updated.) Histoplasmosis. Available online at http://www.cdc.gov/fungal/diseases/histoplasmosis/index.html. Accessed August 27, 2016.
Centers for Disease Control and Prevention (February 13, 2014 updated.) Pneumocystis Pneumonia. Available online at http://www.cdc.gov/fungal/diseases/pneumocystis-pneumonia/index.html. Accessed August 27, 2-16.
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