Aspergillus fumigatus isolated from clinical settings is resistant to agricultural fungicides.
Infections have long been a deadly problem for hospital patients. Though modern medicine has an impressive array of antimicrobial drugs at its disposal, pathogens continue to evolve resistance, creating ever more dangerous infections as the microbial “arms race” escalates.
Overprescribing of antibiotics is one source of resistance, but there could be another culprit further afield. In a new publication in G3: Genes|Genomes|Genetics, fungal biologists Michelle Momany and Marin Brewer report their finding that some strains of a pathogenic fungus apparently acquired antifungal resistance in an agricultural setting rather than a clinical one. Genetic analysis revealed that strains of the fungus Aspergillus fumigatus that were resistant to antifungals used in people had also developed resistance to fungicides used only on plants.
Fungal infections endanger both plants and people
Momany and Brewer are part of the Fungal Biology Group at the University of Georgia, one of the largest fungal biology research groups in the world. Fungal diseases are a major problem both clinically and in agriculture, but doctors generally use different compounds to treat people than farmers use to treat crops. A class of antifungals known as azoles, however, is used in both people and plants. Many different azoles are currently available, and though they are considered “moderate” in terms of the risk of fungi developing resistance, azole-resistant strains of the fungus Aspergillus fumigatus have begun turning up more frequently in hospitals.
Unlike drug-resistant bacteria, which can spread from person to person, A. fumigatus is always picked up environmentally. There’s no documented case of anyone getting sick by breathing in Aspergillus exhaled by an infected patient, says Momany. Because of this, fungal researchers suspected A. fumigatus was evolving azole resistance in the field, rather than in patients. Still, there was no way to know for sure that it wasn’t caused by hospital drugs.
From “Big Chicken” to Big Tulip
“The idea came to me when I was reading the book Big Chicken by Maryn McKenna,” says Brewer. In the book, scientists showed that antibiotic-resistant bacteria had moved from chickens to humans – not the other way around – by showing that bacteria isolated from people contained genetic evidence of resistance to compounds used only in chickens. Brewer decided to apply that same logic to Aspergillus. “I thought it would be interesting to look for the signatures for resistance to fungicides only used in agricultural environments,” she says.
The researchers analyzed 700 different isolates of A. fumigatus collected from compost heaps, soil samples, and plant debris from 56 sites around Georgia and Florida. They sequenced and analyzed the genomes of 135 of these isolates. Most of the sites had a history of azole fungicide use, but two were organic sites with no fungicide use for 10 years. They also analyzed publicly available genome data of A. fumigatus samples from the US, the UK, the Netherlands, and India that were resistant to multiple azole compounds.
They found that A. fumigatus in the environment that carried resistance to azole compounds had often developed resistance to two other classes of fungicides used only in agriculture, benzimidazoles (MBC) and quinone outside inhibitors (QoI). Even more tellingly, A. fumigatus samples collected from patients carried the genetic markers indicating resistance to MBC and QoI.
“Those signatures showed that they were exposed to fungicides in an agricultural environment, and we’re finding them in strains from patients in hospital environments,” says Brewer.
The first hint that agricultural fungicides might be a problem in hospitals came from the Netherlands, the world’s major supplier of tulips and other ornamental flowers. “It turns out a tulip bulb is a wonderful place for fungi to grow,” Momany says. “Nobody wants decorative flowers with mold spots on them. To prepare these for shipping, they’re treated with azoles.” Discarded plant matter from these industrial tulip farms, she says, can spread azoles into the surrounding environment. Strikingly, Momany points out, A. fumigatus isn’t even dangerous to plants. It’s not the intended target of agricultural azole use, but because it’s so widespread, it gets exposed incidentally. “Once those azoles are in the environment, then the A. fumigatus that’s there develops its own resistance,” she says.
People are likely to encounter azole-resistant A. fumigatus in compost or in flower beds. “Compost is definitely a hot spot for Aspergillus that’s azole resistant,” says Brewer. “People who are immunocompromised should be very careful around compost, flower beds, or dusty areas where there can be a lot of fungi.”
This study is one of the first to characterize a fungal pathogen that has picked up antifungal resistance in an agricultural setting and carried that resistance into the clinic. “There could be a lot of others, and people just haven’t looked,” Brewer says.
CITATION:
Evidence for the agricultural origin of resistance to multiple antimicrobials in Aspergillus fumigatus, a fungal pathogen of humans
S. Earl Kang, Leilani G. Sumabat, Tina Melie, Brandon Mangum, Michelle Momany, and Marin T. Brewer
G3: GENES|GENOMES|GENETICS February 2022, jkab427
Caroline Seydel is an independent science writer based in Los Angeles, CA. She has a MS in genetics from Stanford University. Her writing has appeared in Nature Biotechnology, Genetic Engineering News, and Forbes.com.
View all posts by Caroline Seydel »Read more in
-
Hongyu Zhao joins GENETICS as new Senior Editor
A new senior editor is joining GENETICS in the Statistical Genetics and Genomics section. We’re excited to welcome Hongyu Zhao to the editorial team. Hongyu ZhaoSenior Editor Hongyu Zhao is the Ira V. Hiscock Professor of Biostatistics, Professor of Genetics, and Professor of Statistics and Data Science at Yale University. He received his BS in…
-
GSA Member Julio Molina Pineda Receives DeLill Nasser Award, Shines at TAGC 2024
“At any career stage, the GSA membership is an amazing investment for any genetics professional!” Julio Molina Pineda is a PhD Candidate in Cell and Molecular Biology and a Research Assistant at the University of Arkansas, and a Doctoral Academy Fellow at the Lewis Lab. In 2023, Julio was awarded the DeLill Nasser Award for…
-
In Memoriam: Ellsworth Herman Grell (1932–2023), a pioneer of Drosophila genome engineering and annotation
Ellsworth (Ed) Grell blessed the Drosophila community through three enduring legacies: as a pioneer of chromosome mechanics, as a primary organizer and synthesizer of genetic knowledge in Drosophila, and as a graceful mentor to those fortunate to have known him personally. Ed grew up in rural Nebraska, completed his undergraduate studies at Iowa State, and…
-
Congratulations to the #Fungal24 Poster Award winners!
We are pleased to announce the recipients of the GSA Poster Awards for posters presented at the 32nd Fungal Genetics Conference! Undergraduate and graduate student members of GSA were eligible for the awards, and a hard-working team of judges made the determinations. Congratulations to all! Felicia Ebot Ojong, The University of Georgia My research is focused…
-
Poster presentation tips for TAGC 2024
You’ve been selected to present a poster at The Allied Genetics Conference 2024 in March—you’ve celebrated, made plans to attend, now what? This is an exciting opportunity to showcase your research and engage with fellow members of the genetics community, so you want to make sure you’re prepared. We wanted to offer you some tips…
-
Maximize your TAGC 2024 experience
A guide to all that National Harbor & DC have to offer Are you joining us for The Allied Genetics Conference 2024 in March? Make the most of your #TAGC24 experience in National Harbor! We know the science will keep you busy, but you deserve to unwind and have some fun, so we’ve curated a…
-
Early Career Leadership Spotlight: Sarah Petrosky
We’re taking time to get to know the members of the GSA’s Early Career Scientist Committees. Join us to learn more about our early career scientist advocates. Sarah PetroskyMultimedia SubcommitteeUniversity of Pittsburgh Research Interest I am interested in understanding adaptation that has been happening recently in populations by dissecting the ways that genes underlying an adaptation…
-
TAGC 2024 Early Career Award Winners
GSA is pleased to announce the winners of the early career awards presented at The Allied Genetics Conference 2024. These awards are specific to particular TAGC communities and recognize early career scientists’ outstanding work on their respective research organisms. The awardees will present their talks in keynote sessions at TAGC 2024. Don’t miss the opportunity…
-
Preeminent geneticists recognized with revamped GSA Awards
In 2022, GSA’s Board of Directors launched an audit to review the five major awards conferred by the Society. Today, we are thrilled to announce the recipients of the reimagined GSA Awards, including the new Genetics Society of America Early Career Medal. The scientists honored this year are recognized by their peers for their outstanding…
-
Fly Board funds outreach programs to spread the word about Drosophila research
In 2020, the Fly Board voted to use part of its reserve fund to support efforts to increase trainee participation as well as equity and diversity in the Drosophila community. An awards committee decides how the money will be spent each year, and from 2020–2022, the committee posted a very broad call for applications from…
-
New members of the GSA Board of Directors: 2024–2026
We are pleased to announce the election of four new leaders to the GSA Board of Directors: 2024 Vice President/2025 President Brenda Andrews Professor, University of Toronto It’s an honor to continue my association with the Society by serving as Vice President of the Board of Directors. I have broad knowledge of the ongoing activities…
-
Early Career Leadership Spotlight: Caroline Muirhead
We’re taking time to get to know the members of the GSA’s Early Career Scientist Committees. Join us to learn more about our early career scientist advocates. Caroline MuirheadCommunication and Outreach SubcommitteeWorcester Polytechnic Institute Research Interest I didn’t always know I wanted to make science my career. In fact, I started college as an engineering major.…