HOW DOCTORS DIAGNOSE INVASIVE CANDIDIASIS

Candida is diagnosed a number of different ways, with the gold standard being culture. Because Candida lives on many of our body surfaces already (when it’s not invasive), it’s important to distinguish Candida colonization from invasive forms. We are usually not concerned about Candida colonization except in cases of Candida auris. Doctors test for Candida auris colonization by swabbing a patient’s armpits or groin.

Some of the tests to diagnose yeasts and Candida include:

Fungal culture tests for the presence of live fungi that can grow in culture. While fungal culturing (growing in a lab) is slow and may miss some cases, it is still considered the gold standard for diagnosing Candida infections. Culturing is also needed for antifungal susceptibility testing, which provides information about which drugs are likely to work for particular Candida species.

Histopathology is done on material taken from a normally sterile site. It is helpful for testing for invasive candidiasis in a particular body region. The biopsy required can be difficult to obtain in a medically fragile person, and histopathology doesn’t always distinguish common colonization from an invasive infection.

Beta-D-Glucan is a test done on blood that identifies a sugar found in fungi. Because the test is done on blood, it has a quick turnaround time. It’s often repeated over time in patients who are at risk for invasive candidiasis to pick up the infection as early as possible. The test can have a lot of false positives, since other fungal infections and sometimes other medications can make it positive.

Molecular tests include polymerase chain reaction (PCR) and metagenomic next-generation sequencing. These tests for genetic material are relatively new and have not been as extensively studied as the older tests. Nevertheless, they hold promise for providing species-level data information and sometimes antifungal susceptibility.

Antifungal susceptibility testing is performed after initial testing has established the Candida infection. It helps determine which medicine is likely to work. It is usually done on a culture.