At a glance
- Drug-resistant invasive candidiasis infections are increasing in the United States.
- Healthcare providers can use laboratory testing to guide treatment.
- Laboratory testing also produces surveillance data helpful for monitoring trends.
- Use antifungals appropriately to slow the development of drug resistance.
Overview
Candidiasis infections are treated with antifungal drugs. Drug resistance is increasing among invasive candidiasis cases, which are Candida infections of internal organs. Candidemia, bloodstream infections, are a subtype of invasive candidiasis. Only a few types of antifungal drugs are available to treat invasive Candida infections. As a result, drug-resistant candidiasis infections can be difficult, or impossible, to treat.
Preventing infections and using antifungals appropriately can help prevent increasing drug-resistant candidiasis. Healthcare providers can follow infection prevention and control protocols and use laboratory testing to guide treatment. Everyone can help by following healthcare providers' instructions or directions on antifungal packaging.
Testing-informed treatment
Healthcare providers can order diagnostic testing to guide treatment if they suspect invasive candidiasis. Laboratory tests can identify the species causing infections and help determine whether different antifungals are effective treatment (antifungal susceptibility testing).
Selecting effective treatment
Most of the time, echinocandins are the first-choice antifungal treatment for invasive candidiasis, including bloodstream infections. According to the data, less than 1% of bloodstream infections are resistant to echinocandins.
Fluconazole may be appropriate in some situations depending on test results for species and antifungal susceptibility. An estimated 6% of infections are resistant to fluconazole.
As antifungal-resistant Candida increases, it becomes more important to use diagnostic testing to determine treatment, and in some cases, whether new antifungals are necessary.
The path of yeast resistance
Drug-resistant Candida species
Resistance to antifungals is more common and emerging in some Candida species. Three species of Candida cause most drug-resistant invasive candidiasis infections.
Candida auris
C. auris recently emerged around the world and is typically resistant to at least one antifungal. In the United States, over 90% of samples are resistant to fluconazole. Echinocandin-resistant infections are increasing but are still rare (less than 1%).
Candida glabrata
C. glabrata, a common cause of invasive Candida infections, is more often resistant to fluconazoles compared to most other species. Around 5% of invasive C. glabrata cases are resistant to one or more antifungals. Resistance to echinocandins, the first-line treatment, is increasing.
Candida parapsilosis
C. parapsilosis is also a leading cause of invasive Candida infections. It is more common among premature neonates (newborns) and people who have cancer or organ transplants. In recent years, countries around the world have reported notable increases in fluconazole-resistant C. parapsilosis. In some parts of the world, estimates of fluconazole resistance are over 30%.
Emerging drug-resistant C. parapsilosis
CDC's Emerging Infections Program (EIP) conducts population- and laboratory-based surveillance of Candida bloodstream infections (candidemia) at 10 sites. EIP data, presented below, show the percentage of all C. parapsilosis specimens from bloodstream infections that were fluconazole-resistant each year.
Noninvasive infections
Non-invasive infections are Candida infections that do not affect the blood or internal organs. Based on limited data, fluconazole resistance is a concern in vulvovaginal candidiasis (VVC), a common non-invasive infection.
There is not enough evidence on antifungal resistance in other types of non-invasive candidiasis, like oropharyngeal Candida infections ("thrush"), but it is possible that some infections are resistant.
It is challenging to get data on non-invasive infections for a few reasons:
- Healthcare providers typically do not order laboratory tests for noninvasive infections.
- Some people use over-the-counter antifungal products or never seek medical care.
How to stop emerging resistance
There are two main ways to help stop the emergence of drug resistance:
- Reducing invasive infections by implementing recommended infection prevention and control practices.
- Using antifungals appropriately (antifungal stewardship). This means giving patients the right drug at the appropriate dose for the correct amount of time.
What healthcare providers can do
Healthcare providers can help prevent the emergence of resistant Candida infections by:
- Using diagnostic testing, including species identification and antifungal susceptibility testing, to guide treatment of infections.
- Diagnostic testing is critical for invasive infections, but can be considered for non-invasive infections, too.
- Referring to surveillance data of regional or facility trends to guide treatment.
- Considering practices like Therapeutic Drug Monitoring to determine the precise dosing, when appropriate.
- Toda M, Williams SR, Berkow EL, Farley MM, Harrison LH, Bonner L, et al. Population-based active surveillance for culture-confirmed candidemia — four sites, United States, 2012–2016. MMWR Surveill Summ 2019;68:1–15.