“One Health” is getting a lot of talk (but still not enough action) these days. It deals with the intersection of human health, animal health and the environment. Unfortunately, all of these components don’t get treated equally, and the environment often gets ignored. There are a variety of reasons for that, which I won’t get into (at least in this post).
The environment plays an often-forgotten role in antibiotic resistance, through things like contamination of soil and water sources by agricultural runoff, human sewage, and waste produced during pharmaceutical manufacturing, not to mention the ongoing biological warfare that bacteria in the environment wage on each other (most of our natural antibiotics were originally derived from environmental bacteria or fungi). While we focus on use of antimicrobials in animals and humans, they’re also used in plants. Recently, there has been attention focused on the potential role of antifungals use in plants (e.g. vegetables, fruits) on resistance in a very nasty emerging pathogenic fungus called Candida auris. This fungus is (currently) a rare cause of disease in people, but kills ~35% of people who get infected with the resistant form, and infection rates have been increasing internationally.
A recent paper in Emerging Infectious Diseases (Chen et al. 2019) highlights another related issue. The authors looked a different fungus, Aspergillus fumigatus, found in agricultural fields in China. About 10% of the A. fumigatus that they found were resistant to azoles, a common class of antifungal drugs. Eighteen of 21 (86%) of the resistant isolates were from strawberry fields. They also found residual antifungal levels in the soil at many sites, including the drug defenoconazole in 8/10 strawberry fields, and prochloraz in 7/10 strawberry fields.
It’s hard to say what this means for human or animal health, but it’s a concern. The authors concluded “The management of fungicide use in agricultural fields, especially those serving as potential resistance hotspots, such as strawberry fields, is needed to curb the emergence of antifungal drug resistance in clinics.”