The isolation of a pan-echinocandin-resistant Candida parapsilosis strain (anidulafungin, caspofungin, micafungin and rezafungin EUCAST MICs > 8 mg/L) from urine of a patient following prolonged exposure to echinocandins (38 days of micafungin followed by 16 days of anidulafungin) is described. The isolate harbored the novel alteration F652S in the hotspot 1 region of fks1. Isogenic C. parapsilosis bloodstream isolates collected up to 1.5 months earlier from the same patient were susceptible to echinocandins (anidulafungin, caspofungin and micafungin EUCAST MICs 1–2, 1 and 1 mg/L, respectively) and contained wild-type FKS1 sequences. This is the first report of pan-echinocandin resistance in C. parapsilosis associated with an aminoacid change in hotspot 1 region of fks1.

The dihydroorotate dehydrogenase (DHODH) inhibitor olorofim has potent activity against most molds. Recent reports of in vitro acquired resistance to olorofim and an agrochemical fungicide DHODH inhibitor warrant continuous monitoring of in vitro activity of olorofim. We examined the activity of olorofim against a contemporary, large collection of molds and explored the impact of different dilution schemes used for the preparation of microdilution plates. In total, 3,550 isolates referred to Statens Serum Institut during 2020–2023 were analyzed. Isolates were identified with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and/or sequencing. MICs of olorofim, amphotericin B, itraconazole, posaconazole, voriconazole, isavuconazole, and terbinafine were determined using EUCAST E.Def 9.4 and E.Def 11.0 protocols. Drug dilutions were prepared either using serial dilutions directly in the medium (Serial, 2020–2023) or according to the ISO standard 20776-1, with predilutions in DMSO before dilution in medium (introduced during 2023). For isolates with elevated MICs to azoles and olorofim, Cyp51A , Hmg1, and PyrE were sequenced as deemed relevant. Serial dilutions generated MICs 1–2 dilutions higher than the ISO dilutions for olorofim, voriconazole, and isavuconazole. Olorofim MICs were 1 mg/L). Olorofim susceptibility was stable over the years and not affected by Cyp51A, Hmg1, or PyrE Q35L alterations. Olorofim maintained broad, potent in vitro activity over the years against a contemporary collection of molds.

The aim of this paper is to evaluate the performance of the Derma-SR-screen agar for accurate discrimination between susceptible and non-susceptible clinical Trichophyton isolates. Consecutive Trichophyton isolates, received for identification and susceptibility testing, were screened for terbinafine and itraconazole resistance using Liofilchem Derma-SR-screen 4-well panels alongside EUCAST reference testing (E.Def 11.0). EUCAST tentative ECOFFs (terbinafine: T. rubrum 0.03 mg/L; T. indotineae 0.125 mg/L; itraconazole: both species: 0.25 mg/L) were applied for wild-type/non-wild-type classification. Plates were evaluated after 5 days of incubation at 25 °C, with growth graded 0-+++. Faint growth (+) was disregarded. All isolates underwent sqle sequencing. Forty isolates were included; 25 were non-wild-type harbouring Sqle alterations (F397I (number (n) = 1), F397L (n = 17), L393F (n = 3), L393S (n = 1), and Q408L (n = 3)). On day 5, 21 isolates reached +++ growth in the control well; a further 10 reached this level on day 6. The remaining isolates reached a ++/+++ score after 5/6 days (n = 7/n = 2). The 0.125 mg/L terbinafine agar correctly identified 7/8 non-wild-type T. indotineae isolates (4/5 F397L and 3/3 Q408L alterations), all 17 non-wild-type and eight wild-type T. rubrum isolates, as well as the five wild-type isolates of other Trichophyton spp. The 0.016 mg/L agar correctly identified all 17 non-wild-type T. rubrum isolates, but misclassified 2/8 wild-type isolates as non-wild-type. All isolates were wild-type to itraconazole and correctly identified. The Derma-SR-screen agar resulted in correct classification of 24/25 (96%) sqle mutant T. indotineae and T. rubrum isolates. Two wild-type T. rubrum isolates grew at the 0.016 mg/L terbinafine agar suggesting possible reduced agar potency at this concentration.