NEW DELHI, India — Chemicals used to keep apples fresh could also be helping a drug-resistant fungus spread around the world, warns a new study. The fungus which spreads quickly in hospitals and can cause severe yeast infections has already spread to all continents, scientists say.
Apples and other fruits are usually treated with chemicals before being transported to extend their shelf life. While this process helps preserve the fruits’ freshness, it could also help spread a fungus dubbed Candida auris.
C. auris is one of five pathogens identified by the Centers for Disease Control and Prevention in 2019 as posing an urgent threat to public health worldwide. This is because it has proven far more resistant to drugs than other Candida species.
“We still don’t really understand the forces that drive the simultaneous emergence of multiple distinct genetic clusters of C. auris,” says co-lead author Dr. Jianping Xu at McMaster University in Canada, in a statement.
The fungus was first identified in Japan in 2009, but has since spread to all inhabited continents.
For the study, researchers screened 84 fruits which had been collected in 2020 and 2021 from areas of northern India. This included 62 apples, 20 which had been picked in orchards and 42 purchased from a market in Delhi. Drug-resistant strains of C. auris were discovered on eight apples: five Red Delicious and three Royal Gala varieties.
All of these had been stored before being purchased, while none of the freshly-picked apples carried the fungus. This suggests apples could be a “selective force” for the fungus, helping it spread to new hosts.
“Although the study focused on fruits collected from northern India, the spread of C. auris is not an Indian-specific phenomenon,” says Xu.
A growing number of bacteria, viruses, fungi and parasites are becoming resistant to medicines making infections harder to treat.
“When we look at human pathogens, we tend to look at what’s immediate to us,” Xu explains. “But we have to look at it more broadly. Everything is connected, the whole system. Fruit is just one example.”
These drug resistant pathogens have been labelled one of the top 10 global public health threats facing humanity by the World Health Organization.
The findings are published in the journal mBio.
South West News Service writer Tom Campbell contributed to this report.