Azoles on the farm

There’s another agricultural antimicrobial controversy brewing. This time it isn’t antibacterial use in animals, but rather the widespread use of azole antifungal agents to protect crops from fungal disease. The Science summary, here, is good, so read it for yourself (subscription required for access to full text). The bottom line: Paul Verweij's group in the Netherlands is building a strong circumstantial case that agricultural azole use is contributing to the emergence of azole-resistant A. fumigatus infections in humans.

Since I have a particular interest in antifungal resistance, I have long been following the reports from the Netherlands of azole resistant Aspergillus fumigatus infections. Our group has been doing global surveillance for azole resistance among Aspergillus for years, and it has remained very uncommon, although last year we found an apparent cluster of azole-resistant A. fumigatus (we’ll publish the details sometime soon, in collaboration with CDC investigators).

Despite my interest in antifungal resistance, I had no idea until recently that there were so many different azoles being used on crops (at least 30 are marketed for agricultural use!). Interestingly, there is little agricultural azole use in the U.S., far more in Europe and elsewhere. As most of you know, invasive aspergillosis is a devastating infection with a very high mortality rate, and the newer azoles are the drugs of choice for both treatment and prevention in high risk patients. Widespread emergence of azole-resistance among Aspergillus would be a very bad thing, indeed.