Agricultural fungicides generate resistance to antifungal medications, study finds

For the first time, a new study from the University of Georgia has revealed that drugs, used to treat fungal illnesses in plants, are also generating resistance to antifungal medications used to treat people.

A medical illustration of an azole-resistant fungus, Aspergillus fumigatus. Image Credit: CDC

The study concentrated on Aspergillus fumigatus, the fungus that causes aspergillosis, a deadly disease that affects 300,000 people worldwide every year. The research connected agricultural use of azoles (compounds used to treat fungal infections in plants) to decreased efficiency of clinical azoles used to treat fungal infections in people. The study was reported in the journal G3: Genes, Genomes, Genetics.

Our results show that resistance to the compounds used to combat fungal infections in humans is developing in agricultural environments. The samples that we collected in agricultural settings were resistant to both the azoles used in the environment and the clinical azoles used to treat people.”

Marin T. Brewer, Study Corresponding Author and Associate Professor, Mycology, College of Agricultural and Environmental Sciences, University of Georgia

Treatment-resistant fungus is widespread in agriculture industry

Fungi are a threat to both humans and plants, killing approximately 1.5 million people each year and generating 20% crop losses.

It is not uncommon to come across A. fumigatus in the wild. It is in the air, and it is all over the place. It is inhaled normally by most individuals, but it can cause serious illnesses in those with compromised immune systems.

When they are infected with a fungal strain that is resistant to agricultural azole fungicides, clinical azole medications are rendered ineffectual.

Azole-resistant A. fumigatus is widespread in agricultural environments and especially things like compost. Someone who is immune compromised and at risk for fungal infections should be very cautious in those settings.”

Michelle Momany, Study Corresponding Author and Professor, Fungal Biology, Department of Plant Biology, Franklin College of Arts and Sciences, University of Georgia

Strains of treatment-resistant fungus on farms closely related to ones in hospitals

Brewer and Momany, both members of the University of Georgia’s interdisciplinary Fungal Biology Group, headed a team that gathered soil, plant material, and compost samples from 56 sites across Georgia and Florida.

The majority of the sites had lately been treated with a mixture of fungicides that included azoles and other fungicides that are exclusively used in agriculture and not in patients. Two of the locations, on the other hand, were organic and have not used fungicides in over a decade.

The researchers discovered 12 strains of A. fumigatus that were highly resistive to azoles used in agriculture and medicine after retrieving them. The 12 germs were also highly resistant to two non-azole fungicides that are not used to treat people.

The scientists have created a genetic family tree for A. fumigatus strains from the environment and patients using whole-genome sequencing. They discovered that the pathways of azole resistance they observed in agricultural strains mirrored what they detected in patients. Patients’ azole-resistant strains were also resistant to non-azole fungicides that are never used in humans, indicating that these strains had been in agricultural contexts before the patients became ill.

The strains that are from the environment and from people are very closely related to each other. It’s not like there are different strains that are developing resistance in people and in the environment. It’s all the same. So people who have these infections that are resistant have likely acquired them from the environment.”

Marin T. Brewer, Study Corresponding Author and Associate Professor, Mycology, College of Agricultural and Environmental Sciences, University of Georgia

Desperate need for new environmentally friendly fungicides

Eight of the 25 multiazole-resistant isolates studied were also immune to non-azole agricultural fungicides, including eight from agricultural contexts and 12 from patients. These multi-fungicide resistant isolates came from farms in the United States and India, as well as health centers in the United States, the Netherlands, and India.

“This emergence severely limits the usefulness of fungicides to manage plant pathogens while still preserving the clinical usefulness of azoles. We urgently need effective agricultural fungicides that aren’t toxic to the environment that do not lead to the rapid development of widespread resistance in the clinic,” Brewer added.