Appearance of Environment-Linked Azole Resistance in the Aspergillus fumigatus Complex in New Zealand.

BACKGROUND

Until 2020, azole resistance in Aspergillus fumigatus complex isolates in New Zealand was due to cyp51A hot spot mutations. This report details the appearance of environment-linked tandem repeat (TR)-related azole resistance genotypes since 2021.

METHODS

Isolates were tested by broth micro-dilution. Clinical Laboratory Standards Institute criteria were used to define wild type (WT) and non-wild type (non-WT) isolates, which were identified by ß-tubulin gene sequencing and had their cyp51A genotype for azole resistance determined. Whole genome sequencing (WGS) was applied to two patient pairs of sequential WT and non-WT isolates.

RESULTS

From January 2021 to June 2024, 15 of 147 (10.2%) A. fumigatus complex isolates were resistant or non-WT for one or more azole agents. Genotyping detected hot spot mutations in four and TR-associated resistance in nine. No mutations were detected in two isolates. Four of the five TR46 mutations were TR46/Y121F/T289A. Three of the four TR34 mutations were different. WGS of the paired isolates showed that the non-WT isolates were distinct. Azole-containing fungicides are available for home use from garden centres. Patients with TR-associated resistance did not have any obvious exposure to azole-containing fungicides. There was no evidence for healthcare-acquired transmission.

CONCLUSIONS

A. fumigatus sensu stricto isolates with TR-mutations linked to environmental resistance are now present in New Zealand. Those at risk of invasive A. fumigatus infection should receive advice to avoid high-risk exposures. Reintroducing monitoring of azole-containing fungicides is recommended.