Candida auris is a multidrug resistant pathogen that presents a serious global threat to human health. As C. auris is a newly emerged pathogen, several questions regarding its ecological niche remain unexplored. While species closely related to C. auris have been detected in different environmental habitats, little is known about the natural habitat(s) of C. auris. Here, we explored the virgin habitats around the very isolated Andaman Islands in the Indian Ocean for evidence of C. auris. We sampled coastal wetlands, including rocky shores, sandy beaches, tidal marshes, and mangrove swamps, around the Andaman group of the Andaman & Nicobar Islands, Union Territory, in India. Forty-eight samples of sediment soil and seawater were collected from eight sampling sites representing the heterogeneity of intertidal habitats across the east and west coast of South Andaman district. C. auris was isolated from two of the eight sampling sites, a salt marsh and a sandy beach. Interestingly, both multidrug-susceptible and multidrug-resistant C. auris isolates were found in the sample. Whole-genome sequencing analysis clustered the C. auris isolates into clade I, showing close similarity to other isolates from South Asia. Isolation of C. auris from the tropical coastal environment suggests its association with the marine ecosystem. The fact that viable C. auris was detected in the marine habitat confirms C. auris survival in harsh wetlands. However, the ecological significance of C. auris in salt marsh wetland and sandy beaches to human infections remains to be explored. IMPORTANCE Candida auris is a recently emerged multidrug-resistant fungal pathogen capable of causing severe infections in hospitalized patients. Despite its recognition as a human pathogen a decade ago, so far the natural ecological niche(s) of C. auris remains enigmatic. A previous hypothesis suggested that C. auris might be native to wetlands, that its emergence as a human pathogen might have been linked to global warming effects on wetlands, and that its enrichment in that ecological niche was favored by the ability of C. auris for thermal tolerance and salinity tolerance. To understand the mystery of environmental niches of C. auris, we explored the coastal wetland habitat around the very isolated Andaman Islands in the Indian Ocean. C. auris was isolated from the virgin habitats of salt marsh area with no human activity and from a sandy beach. C. auris isolation from the marine wetlands suggests that prior to its recognition as a human pathogen, it existed as an environmental fungus.

Candida auris is a nosocomial pathogen responsible for an expanding global public health threat. This ascomycete yeast has been frequently isolated from hospital environments, representing a significant reservoir for transmission in healthcare settings. Here, we investigated the relationships among C. auris isolates from patients with chronic respiratory diseases admitted in a chest hospital and from their fomites, using whole-genome sequencing (WGS) and multilocus microsatellite genotyping. Overall, 37.5% (n = 12/32) patients developed colonisation by C. auris including 9.3% of the screened patients that were colonised at the time of admission and 75% remained colonised till discharge. Furthermore, 10% of fomite samples contained C. auris in rooms about 8.5 days after C. auris colonised patients were admitted. WGS and microsatellite typing revealed that multiple strains contaminated the fomites and colonised different body sites of patients. Notably, 37% of C. auris isolates were resistant to amphotericin B and a novel amino acid substitution, G145D in ERG2 gene, was detected in all amphotericin B resistant isolates. In addition, 55% of C. auris isolates had two copies of the MDR1 gene. Our results suggest significant genetic and ecological diversities of C. auris in healthcare setting. The WGS and microsatellite genotyping methods provided complementary results in genotype identification.

In 2019, the U.S. Centers for Disease Control and Prevention classified the multidrug-resistant Candida auris as one of five pathogens posing the most urgent threats to public health.

Lodderomyces elongisporus was initially considered a teleomorph of Candida parapsilosis . However, DNA sequence analyses revealed it as a distinctive species.

Candida auris is an emerging fungal pathogen showing resistance to most of the currently available antifungal drugs. The pathogen is spreading rapidly worldwide. It mainly affects immunocompromised individuals such as intensive care unit patients, adults, and newborns who are treated in health care facilities. The isolates can be recovered from a variety of specimens, including mucocutaneous swabs, urine, respiratory specimens, and body fluids; however, bloodstream infections are the most commonly observed invasive infections. The advent of C. auris as a human fungal pathogen has been directly linked to the occurrence of new virulence traits and its ability to adhere to various surfaces to form a multidrug-resistant biofilm. With the lack of distinctive traits in C. auris, its identification has been problematic. The commercially available biochemical tests often misdiagnose the pathogen to phylogenetically related Candida haemulonii species making it difficult for clinicians to initiate proper antifungal treatment in patients. Emergence of resistant isolates has further posed a new challenge to the limited therapeutic options. This review highlights the risk factors involved in infection, virulence traits of C. auris, diagnostic methods, and mechanism of drug resistance along with novel antifungal drugs against this fungal pathogen which could provide direction for future work on it.