Fusarium Fungi and Their Tricky Response to Antifungal Drugs

Fusarium fungi are molds that can cause infections in people, especially those with weak immune systems. They often survive treatment with azole drugs, which are a common type of antifungal medicine. Because of this, the World Health Organization has placed them on its list of priority pathogens.

Researchers collected twenty‑six samples from patients in São Paulo, Brazil. They used DNA sequencing of three genes to tell which Fusarium group each sample belonged to. Then they tested how well the samples resisted voriconazole, an azole drug. They also looked at the CYP51A gene, which is the target of the drug, and at another gene called ABC1 that can pump the drug out of the cell.

The tests showed that the samples needed higher amounts of the drug to stop growth, with the FSSC group needing the most. The CYP51A gene had different amino‑acid patterns in the three groups, but those patterns did not predict the drug‑resistance levels. When exposed to voriconazole, all samples turned on the CYP51A gene strongly, and the FSSC samples showed the biggest increase. The ABC1 gene also went up in the FSSC samples, though not as much as CYP51A. These results suggest that the fungus uses several tactics at once: changes in the drug target, a strong boost of that target when the drug is present, and a modest increase in a pump that can remove the drug.

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