On October 15, 2021, the U.S. Environmental Protection Agency (EPA) announced that it has revised its guidance for evaluating the efficacy of antimicrobial pesticides against Candida auris (C. auris). EPA states that pesticide manufacturers seeking to register their products with a C. auris claim should use this updated guidance to test the effectiveness of the products against a drug-resistant strain of C. auris.
EPA states that C. auris is an emerging, multidrug-resistant yeast (a type of fungus). It can cause serious infections and spreads easily among hospitalized patients and nursing home residents. C. auris can spread in healthcare settings through contact with contaminated environmental surfaces or equipment, or from person to person. According to the Centers for Disease Control and Prevention (CDC), more than one in three patients with an invasive (e.g., affecting the blood, heart, or brain) C. auris infection die.
In 2017, in consultation with the CDC, EPA issued interim guidance for testing the effectiveness of hospital disinfectants against C. auris. Subsequently, based on input from the CDC on its tracking of clinical cases of multi-drug resistant C. auris isolates in the United States, the laboratory data were generated to ensure antimicrobial efficacy against a more relevant strain of the pathogen.
Working closely with experts from the CDC, EPA conducted a comparative evaluation of isolates and found that the drug-resistant isolates were more tolerant to some disinfectant treatments. Since a drug-resistant isolate (AR Bank #0385) is highly relevant to current outbreaks in the United States, it is considered a suitable test microbe for regulatory purposes.
The guidance provides recommendations for laboratory methodology on how to:
produce and store cultures of drug-resistant C. auris, and
evaluate the effectiveness of antimicrobial products intended to treat surfaces contaminated with drug-resistant C. auris.
Under the updated guidance, all new products seeking registration with claims against C. auris should test for efficacy using the more relevant strain (AR Bank #0385). Efficacy testing using AR Bank #0381 is acceptable in some cases where the study initiation date is between October 15, 2020, and October 15, 2021. For study initiation dates between October 15, 2020, and October 15, 2021, EPA will accept studies conducted with isolate AR Bank #0381 for products whose active ingredients are either sodium hypochlorite or hydrogen peroxide plus acetic acid. For products with other active ingredients, it will be necessary to retest using isolate AR Bank #0385.
Existing antimicrobial products with C. auris claims based on the previous strain (AR Bank #0381) will be allowed to retain their claim of effectiveness against C. auris. To claim effectiveness against drug-resistant C. auris, EPA requires retesting with the more relevant strain (AR Bank #0385) identified in the updated guidance and according to the revised test method.