Aspergillus is a common fungus that produces spores, which can be found in many indoor and outdoor environments. A new study has shown that these spores can also be found in commercially available gardening supplies. There are about 180 species of this fungus, and fewer than 40 have been shown to cause infection in people. Most people probably inhale some Aspergillus spores at some point, and our bodies can usually identify and eliminate fungal infections, including those caused by Aspergillus, pretty easily most of the time. Usually those infections don't cause symptoms. However, people with compromised immune symptoms can be vulnerable to more severe infections.
Aspergillosis is an Aspergillus infection that can be mild to severe, and symptoms including coughing, breathing difficulties, and in some cases, headache, nasal congestion, or fatigue. Cases can become more serious when they are caused by a mutlidrug-resistant strain of Aspergillus.
The World Health Organization has identified a species known as Aspergillus fumigatus as a critical public health threat, and infections can be deadly to the immunocompromised. Right now, about 2 million people around the world are infected with Aspergillus fumigatus every year.
A new study has shown that soil, compost, and flower bulbs that are sold at big box stores often carry multidrug-resistant Aspergillus fumigatus. The findings have been reported in Applied and Environmental Microbiology.
"People don't think of tulips as deadly, but they could be," said corresponding study author Marin Brewer, a professor at the University of Georgia. "Gardening is a nice, stress-relieving hobby. 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."
In this study, the researchers analyzed samples of soil, compost, and bulbs of flowers including daffodils, dahlias, and tulips obtained from retailers from 2019 to 2021. Over 500 different strains of Aspergillus fumigatus were identified in the samples, which included a variety of brand names.
Many different illnesses, such as diabetes or cystic fibrosis and infections such as HIV or COVID-19 can disrupt and weaken the immune system. Certain treatments like immunosuppressants for an autoimmune disease or organ transplant, or cancer treatments like chemotherapy can also impair immune responses to infection.
Increasing numbers of people have impaired immune systems at a time when multidrug-resistant fungal infections are becoming more common.
"We found dozens of strains of resistant fungi in just 1 gram of compost," Brewer said. "Based on our findings, there could be tens of thousands of potentially resistant strains in one bag of compost."
Since Aspergillosis is caused when spores of Aspergillus are inhaled, the researchers suggested that anymore with a compromised immune system should discuss the potential risks of gardening with their physicians. They also noted that N95 masks may also provide some protection.
Brewer has decided not to plant anymore flower bulbs, and may also stop using commercial compost, until the problem has been solved by the industry.
Sources: University of Georgia, Applied and Environmental Microbiology