Terbinafine is one of the allylamine antifungal agents whose target is squalene epoxidase (SQLE). This agent has been extensively used in the therapy of dermatophyte infections. The incidence of patients with tinea pedis or unguium tolerant to terbinafine treatment prompted us to screen the terbinafine resistance of all Trichophyton clinical isolates from the laboratory of the Centre Hospitalier Universitaire Vaudois collected over a 3-year period and to identify their mechanism of resistance. Among 2,056 tested isolates, 17 (Ϸ1%) showed reduced terbinafine susceptibility, and all of these were found to harbor SQLE gene alleles with different single point mutations, leading to single amino acid substitutions at one of four positions (Leu 393 , Phe 397 , Phe 415 , and His 440 ) of the SQLE protein. Point mutations leading to the corresponding amino acid substitutions were introduced into the endogenous SQLE gene of a terbinafine-sensitive Arthroderma vanbreuseghemii (formerly Trichophyton mentagrophytes) strain. All of the generated A. vanbreuseghemii transformants expressing mutated SQLE proteins exhibited obvious terbinafine-resistant phenotypes compared to the phenotypes of the parent strain and of transformants expressing wild-type SQLE proteins. Nearly identical phenotypes were also observed in A. vanbreuseghemii transformants expressing mutant forms of Trichophyton rubrum SQLE proteins. Considering that the genome size of dermatophytes is about 22 Mb, the frequency of terbinafine-resistant clinical isolates was strikingly high. Increased exposure to antifungal drugs could favor the generation of resistant strains.

The mechanisms of terbinafine resistance in a set of clinical isolates of Trichophyton rubrum have been studied recently. Of these isolates, TIMM20092 also showed reduced sensitivity to azoles. The azole resistance of TIMM20092 could be inhibited by milbemycin oxime, prompting us to examine the potential of T. rubrum to develop resistance through multidrug efflux transporters.

C andida auris is an emerging, multidrug-resistant pathogen associated with a high mortality rate. Since this yeast's first identification and classification by our research group in 2009 (1), there have been several outbreaks linked to this pathogen in health care facilities around the world (2-10). It has been reported that most clinical isolates are resistant to azoles, and about half of the isolates also are resistant to more than one class of antifungal agent, limiting the therapeutic options (2-8, 10). Moreover, the pathogen can persist on environmental surfaces for weeks, resulting in the yeast's spread among patients in health care facilities (11). Therefore, accurate identification of C. auris is critical for controlling this pathogen's prevalence around the globe and preventing further outbreaks. Traditional methods have proven to be unsuitable for accurate identification of C. auris. Automated identification systems popularly used in clinical laboratories, like the Vitek 2 YST card (bioMérieux, Marcy I'Etoile, France) or API20C AUX (bioMérieux), commonly misidentify C. auris as Candida haemulonii or Rhodotorula glutinis, respectively (2, 4-7, 12), and MicroScan misidentifies C. auris as any of several different Candida species (12). On the other hand, specialized methods can provide accurate identification. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is useful for identifying C. auris, if a proper reference database is available (13-15). Moreover, sequencing of the genes for the D1/D2 region of large subunit ribosomal DNA (rDNA) or of the internal transcribed spacer (ITS) region of rDNA is a reliable option. Real-time PCR assays also are useful for detection of C. auris (16, 17). However, these methods may not be suitable for local or small clinical settings due to financial and technical issues. As shown in the present study, we have successfully devised and assessed the reliability of a loop-mediated isothermal amplification (LAMP)-based identification approach specific to C. auris, enabling distinction of the pathogen from closely related species and other fungi. To design the LAMP primers, the genome sequences of four Candida species, C. auris (PRJNA342691), C. tropicalis (GCF_000006335.2), C. albicans (GCA_000182965.3), and C. lusitaniae (LYUB00000000.2), were aligned and compared using Mauve (version 20150226) (18). An 869-bp DNA fragment of the C. auris genome (accession no. XM_018317007) that encodes a pyruvate:ferredoxin oxidoreductase domain (19) was identified as sharing low similarity with other Candida species. This DNA fragment was amplified using EmeraldAmp PCR master mix (TaKaRa Bio, Inc.

Trichophyton indotineae causes dermatophytosis that is resistant to terbinafine and azole compounds. The aim of this study was to determine the mechanisms of resistance to itraconazole (ITC) and voriconazole (VRC) in strains of T. indotineae .

The activities of novel azoles compared to those of five antifungal drugs against clinical ( = 28) and environmental ( = 102) isolates of black mold and melanized yeast were determined. Luliconazole and lanoconazole had the lowest geometric mean MICs, followed by efinaconazole, against tested isolates compared to the other drugs. Therefore, it appears that these new imidazole and triazole drugs are promising candidates for the treatment of infections due to melanized fungi and their relatives.