The emerging multidrug-resistant yeast organism Candida auris forms biofilms that enhance both its resistance and its virulence, according to in vitro analyses.
C. auris first attracted attention in 2009 because of its resistance to azoles and amphotericin B. Since then, it has been identified as the cause of life-threatening invasive infections worldwide, including hospital outbreaks across Asia and South America, wrote Leighann Sherry, PhD, a medical mycologist at the University of Glasgow, and her associates.
To determine whether the pathogen has the capacity to form biofilms, the investigators propagated several different strains in the laboratory and examined their development. In three separate trials, eight samples of each strain grew biofilms, which constitute “a key driver of candida pathogenicity.” In antifungal susceptibility tests, caspofungin was completely ineffective, an unexpected finding because the agent usually is highly effective against other candida species. Amphotericin B, liposomal amphotericin B, and fluconazole also were ineffective; micafungin and chlorhexidine were the most effective at clearing C. auris.
Biofilm formation “contributes not only to C. auris virulence but also to its [resistance] in hospital environments, increasing its ability to cause outbreaks,” Dr. Sherry and her associates said (Emerg. Infect. Dis. 2017 Feb;23[2]:328-31).
“Our findings suggest it is improbable that the spread and prevalence of C. auris can be controlled with antifungal stewardship approaches alone,” they noted, adding that “infection-prevention measures targeting C. auris biofilms in patients, on medical devices, and in the hospital environment will be required,” they noted.