Deadly drug-resistant superbug found in the wild in Andamans

The study, carried out by the Vallabhbhai Patel Chest Institute, has for the first time established that the fungus is found in tropical marshes and marine environments, outside hospital environments.

The study sampled coastal wetlands, including rocky shores, sandy beaches, tidal marshes, and mangrove swamps around the Andaman group of islands — 48 samples of sediment soil and seawater were collected from eight sampling sites 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.

Two colonies of C.auris were found at the salt marsh from the composite soil sediment and 22 colonies were found at the beach and these were distributed in both the sediment and water samples, establishing that the fungus is both marine and terrestrial.

“Interestingly, both multidrug-susceptible and multidrug-resistant C.auris isolates were found in the sample. The fact that viable C.auris was detected in the marine habitat confirms C.auris survival in harsh wetlands. Fungi are present in the environment as degraders of organic matter. Fungi predominately thrive in tropical and subtropical areas,” Dr Anuradha Chowdhary, lead author of the research, said.

“The significance of this report is that so far, the environmental niche of C.auris was not explored. So, this is the first study that detected this fungus in the environment. It was not known before this that it existed outside the hospital environment,’’ she said.

According to Dr Chowdhary, the transmission pathway of the fungus – from the environment to patients in hospitals — is yet to be established and still needs to be explored. But what is now known is that even the drug-susceptible fungus, that can be treated with medication, can adapt inside the human body and become drug resistant. This makes the pathogen difficult to treat.

The C.auris can be deadly for immunocompromised patients. While incidence of patients dying from this fungal infection has been found to be higher in other countries, such as the US and the UK, its prevalence is less in Indian hospitals. But the research has found presence of the fungal infection in patients in ICUs across the country. The fungus is deadly when it enters the bloodstream, or inhabits the body of a patient suffering from a serious disease such as cancer.

“Generally, fungi have high mortality in immunocompromised patients. Serious invasive infections due to fungi occur only in

immunosuppressed patients who are already sick. So, the true attributable mortality due to C.auris is not truly known. However, some studies have reported mortality in 30-60% patients who already were critically ill and admitted in ICUs. It can enter the body through invasive procedures or even devices like catheters,” Dr Chowdhary said.

Previous theories regarding C.auris have said that the fungus might be native to wetlands and that its emergence as a human pathogen might have been linked to global warming effects on wetlands. The C.auris’ thermal and salinity tolerance is because of its adaptation to global warming, which makes the human body more susceptible as a

host since most other fungi cannot flourish due to the high temperatures inside the body. But this theory also needs more investigation, experts have said.

An escalating number of infections across the globe in healthcare facilities have been attributed to the unique characteristics of this yeast because it can survive and persist within the hospital environment for prolonged periods. Its ability to survive on dry environmental surfaces for prolonged periods suggests that this yeast is well adapted to survival outside human host settings as well.

“Candida auris belongs to the Candida haemulonii clade of the Metschnikowiaceae family of the order Saccharomycetales. The related species of the Metschnikowiaceae family have been detected in plants, insects, and aquatic environments, as well as from human body sites.

The closest known relative of C.auris is C. haemulonii, which was first discovered in 1962 from the gut of a blue-striped grunt fish, the skin of dolphins, and the seawater off the coast of Portugal.

In contrast to the related species, C.auris had not been reported from natural environments. The retrospective analyses of clinical yeasts showed that the earliest known clinical isolates of C.auris date back to 1996 in South Korea and 1997 in Japan. However, unlike the clinical settings, the detection of C. auris in the natural environment has not been explored,” the study stated.