A plain language summary of how some fungi samples that show resistance to antifungal medicines have changes in their genes.

WHAT IS THIS SUMMARY ABOUT?: Aspergillus fumigatus (shortened to A. fumigatus) is a fungus (plural: fungi) that can cause a serious infection in some people. A. fumigatus can become resistant to medicines known as azoles (isavuconazole, itraconazole, posaconazole, and voriconazole). This means they stop working and are not able to kill the fungus. Fungi can become resistant through changes in their genes, which are called mutations. Scientists looked at previously collected samples from people infected with A. fumigatus and found that 36 of the samples showed resistance to an azole. In 35 of these samples, scientists looked for mutations in 50 genes. These 50 genes are known to play a role in azole resistance and/or are important for fungal survival.

WHAT WERE THE RESULTS?: In total, 18 out of 36 samples (50%) showed resistance to isavuconazole only. Of these, 12 had mutations in 4 genes important for fungal survival (called erg3C, erg2, erg7B and erg4B). Mutations were found in 2 genes that are the most common causes of azole resistance (called cyp51A and cyp51B). The most common mutation, called cyp51A TR34/L98H, was found in 9 samples. Of these, 8 samples showed resistance to all 4 of the azoles tested.

WHAT DO THE RESULTS OF THE STUDY MEAN?: Studying mutations that make fungi resistant to medicines helps to make sure that people with fungal infections get treated with medicines that will work for them.