‘Landmark discovery’: C. auris isolated from environment for first time
Researchers isolated Candida auris from a salt marsh and sandy beach in the Andaman Islands, suggesting that before its recognition as a human pathogen, it existed as an environmental fungus, they said.
C. auris was first isolated clinically in 2009 from a patient in Japan, although the earliest known strain dates to 1996. It has endured as an important cause of hospital outbreaks around the world, including in the United States.
“For almost 2 decades this yeast has been in clinical settings, but its natural reservoir in the environment was not known,” Anuradha Chowdhary, MD, PhD, a professor of medical mycology at the Vallabhbhai Patel Chest Institute at University of Delhi, told Healio.
“The closest related species of C. auris have been isolated from a variety of marine and terrestrial environments, in addition to human sources. So, we thought of exploring the marine environment to detect its presence in the natural environment,” Chowdhary said.
Chowdhary and colleagues sampled coastal wetlands — including rocky shores, sandy beaches, tidal marshes and mangrove swamps — around the Andaman group of the Andaman and Nicobar Islands in India. In total, they collected 48 samples of sediment soil and seawater from eight sampling sites.
Overall, C. auris was isolated from two of the eight sampling sites a salt marsh with no or limited human activity and a sandy beach with human activity. The researchers reported that both multidrug-susceptible and multidrug-resistant C. auris isolates were found in the samples, and an analysis showed they were similar to other isolates from South Asia.
The researchers said the discovery “suggests [C. auris’] association with the marine ecosystem,” and that the fungus can survive in harsh wetlands. The significance to human infections “remains to be explored,” they wrote, but experts in the field hailed the finding as a milestone.
“This landmark discovery is crucial for understanding the epidemiology, ecology, and emergence of C. auris as a human pathogen,” Arturo Casadevall, MD, PhD, chair of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, and colleagues wrote in a related editorial.