Researchers have found high levels of multidrug-resistant fungi in commercially available compost, soil, and flower bulbs, researchers report.
Aspergillus fumigatus is a widespread fungus that thrives in soil. But it also poses a serious risk to human health if inhaled. People with compromised immune systems are particularly vulnerable to the opportunistic fungus, facing a near 100% fatality rate if infected with a multidrug-resistant strain.
“People don’t think of tulips as deadly, but they could be,” says Marin Brewer, a professor in the College of Agricultural and Environmental Sciences at the University of Georgia and lead author of the study in the journal Applied and Environmental Microbiology.
“Based on our findings, there could be tens of thousands of potentially resistant strains in one bag of compost.”
“Gardening is a nice, stress-relieving hobby,” Brewer says. “But I’m nervous for people who may not be aware that working with compost and flower bulbs could pose a risk to their health.”
Those people include individuals with chronic obstructive pulmonary disease (also known as COPD), cystic fibrosis, Type 2 diabetes, HIV/AIDS, and even COVID-19. Cancer patients and anyone taking immunosuppressant drugs are also vulnerable.
And research shows more people are at risk of developing fungal infections than before.
Deadly fungi
The World Health Organization recently named Aspergillus fumigatus as one of the most critical fungal threats facing the world. Aspergillus fumigatus infects more than 2 million people annually worldwide.
Aspergillosis, the disease caused by the fungus, is one of the most frequent causes of death in immunocompromised patients. About eight out of every 10 invasive aspergillosis patients die, according to a recent study. Although less common, the fungus can even pose a threat to individuals with healthy immune systems.
Known as aspergillomas, the fungus can create a clump on the lung. While some healthy individuals may clear the infection on their own with minimal to no symptoms, other aspergilloma patients require antifungal medications or surgery to stop the infection from spreading.
The problem is that the treatments for human patients rely on the same mechanisms to fight the fungi as those used in agricultural settings. And they’re becoming less effective.
Soil, compost, tulips, and daffodils
For the study, the researchers sampled products including compost, soil, flower bulbs, and a variety of food products sold at big box retail stores from 2019 through 2021.
The study found more than 500 strains of Aspergillus fumigatus in the products, which included an assortment of different brands. Of the 525 samples, 90% were found in flower bulbs, soil, compost, and peanuts.
Most of the drug-resistant strains of fungi were found in soil, compost made from manure, and flower bulbs, including daffodils, dahlias, gladioli, and tulips.
“We found dozens of strains of resistant fungi in just 1 gram of compost,” Brewer says. “Based on our findings, there could be tens of thousands of potentially resistant strains in one bag of compost.”
Staying safe in the garden
People are infected with Aspergillus fumigatus when they inhale the fungi’s spores.
The researchers highly recommend individuals with compromised immune systems take precautions when gardening and discuss the potential risks with their physicians. Devoted gardeners can also wear N-95 masks to provide some protection.
The agricultural industry is working to address the problem, but in the meantime Brewer says she personally won’t be planting flower bulbs. And she’ll probably pass on using commercial compost too.
Source: University of Georgia
