A commonly used fungicide has been revealed to be causing C. tropicalis infections

• Candida tropicalis, a significant fungal pathogen, is causing an increase in azole-resistant infections in clinics.

• Researchers from Fudan University in Shanghai discovered that a fungicide called tebuconazole, widely used by farmers and gardeners, has driven the rise in azole-resistant C. tropicalis infections.

• The tebuconazole-resistant strains exhibited aneuploidy, a deviation from the normal chromosome count for the organism.

• This deviation from normal chromosome complement, known as ploidy plasticity, can lead to serious consequences, such as Down syndrome and prenatal death.

• The researchers found that tebuconazole-resistant strains showed slower growth than their progenitor strains in the absence of antifungals, but grew better in the presence of antifungals.

• The ploidy of tebuconazole-resistant strains ranged from haploid to triploid, with some identified as diploid or close to diploid being segmental aneuploids.

• The aneuploidies created imbalances in the C. tropicalis genome that reduced their growth rate, but enabled the strains to better resist antifungals.

• The researchers also found that the strains with altered ploidy were more virulent than the progenitor strains in mice treated with fluconazole.

• The study also discovered that tebuconazole-resistant strains included stable haploid strains of C. tropicalis, which could mate and introduce their resistance mechanisms into new genetic backgrounds.