Drug-Resistant Fungal Infections: Why They Are Rising and What Helps

Fungal infections that resist antifungal drugs are increasing around the world as more resistant fungi emerge. Antimicrobial resistance happens when germs such as bacteria and fungi develop the ability to defeat the drugs designed to kill them: resistant fungi keep surviving and causing infection even after a patient takes an antifungal.

With only three classes of antifungal drugs, infections resistant to even one can be hard — sometimes impossible — to treat. Some fungi can resist all of them. Candida auris, which emerged worldwide in recent decades, is often resistant to several drugs, and some cases have resisted all three classes. It mostly affects patients who are already very sick and can cause severe illness or death.

A patient receiving azole antifungal medicine. CDC illustration.

How resistance develops

Resistance builds over time as fungi are exposed to antifungals used in human and animal medicine, agriculture and industry, and adapt to survive.

• In medicine, overuse and misuse speed it up: using antifungals for conditions not caused by fungi, doses higher or lower than needed, treatment longer or shorter than needed, and preventive use when risk is not high.
• In agriculture and industry, fungicides — many similar to medical antifungals — are widely used in the environment. When naturally occurring Aspergillus is exposed to them, it can become resistant.

Antifungal use in both medicine and agriculture can lead to resistance. CDC illustration.

Resistant fungi include Aspergillus, certain Candida species and strains, and some dermatophytes — the fungi that cause ringworm. C. auris is especially resistant and can spread quickly in health care settings. The World Health Organization's fungal priority pathogens list, the first global effort to rank fungal pathogens, is meant to guide research, development and public health action.

What CDC is doing

Through its Antimicrobial Resistance Solutions Initiative, CDC:

• tracks resistance in Candida infections at 10 sites through the Emerging Infections Program;
• supports the Antimicrobial Resistance Laboratory Network, whose public health labs test fungi for drug susceptibility;
• uses genomic sequencing and develops new tests to find mutations linked to resistance;
• works with the WHO's Global Antimicrobial Resistance Surveillance System (GLASS) to expand surveillance worldwide;
• analyzes antifungal prescribing across health care facilities and promotes appropriate use.

What everyone can do

Farmers, doctors and veterinarians all have a part in preventing antifungal resistance. CDC illustration.

• Health care facilities can include antifungals in antimicrobial stewardship programs and follow infection-control guidelines, including hand hygiene and disinfection.
• Health care providers and veterinarians can record the dose, duration and reason for every antifungal prescription, test for fungal disease before treating when possible, test for resistance if treatment is failing, and know local resistance patterns.
• Industry can keep up with research on reducing the impact of fungicides and consider integrated pest management, which the WHO recognizes for reducing pesticide use while protecting crop yields.
• Everyone can clean their hands often, learn whether they or a loved one are at higher risk, take antifungals only when needed and exactly as prescribed for the full course, and tell their provider about side effects or a medicine that isn't working.

Sources

• Centers for Disease Control and Prevention: "Antimicrobial-Resistant Fungal Diseases."