Rare modification in the ergosterol biosynthesis pathway leads to amphotericin B resistance in Candida auris clinical isolates

We determined amphotericin B (AmB) susceptibility and sequenced key genes of the ergosterol biosynthesis pathway implicated in AmB resistance (ERG2, ERG3, ERG6, ERG11) of 321 clinical isolates of Candida auris. In antifungal susceptibility testing, 19 (5.9%) isolates were categorized as AmB-resistant (MIC [≥]2 mg/l). Only one AmB-resistant isolate presented a unique non-wild-type ERG6 genotype that was confirmed to confer amphotericin B resistance (MIC >32 mg/l) when introduced into a susceptible strain (MIC = 0.5 mg/l).