Drug Sensitivity and Resistance Mechanism in Aspergillus Section Strains from Japan.

and its related species, known as section , are ubiquitously distributed across the globe and are often isolated from clinical specimens. In Japan, section is second most often isolated from clinical specimens following We determined the species of section isolated in Japan by DNA sequencing of partial β-tubulin genes and investigated drug susceptibility by the CLSI M38-A2 method. The collection contained 20 , 59 , and 39 strains. Drug susceptibility testing revealed 30 to 55% of , 6.8 to 18.6% of , and 79.5 to 89.7% of isolates to be less susceptible (so-called resistant) to itraconazole (ITC) and/or voriconazole (VRC) according to the epidemiologic cutoff values (ECVs) proposed for previously. MIC distributions of ITC or VRC showed no remarkable differences between clinical and environmental isolates. When the sequences were compared between susceptible and resistant strains, 18 amino acid mutations were specific for resistant isolates of and ; however, none of them were confirmed to be associated with azole resistance. Three nonrelated isolates possessed a partial deletion in , likely attributable to being more susceptible to azoles than other isolates. One of five ITC-resistant isolates showed higher expression of than did susceptible strains. Our results show that point mutations may have no association with azole resistance but that in some cases the overexpression of may lead to the azole resistance in these species.