Impact Factor 3.518 | CiteScore 3.62
More on impact ›

Original Research ARTICLE

Front. Cell. Infect. Microbiol., 02 April 2019 |

Identification of Off-Patent Compounds That Present Antifungal Activity Against the Emerging Fungal Pathogen Candida auris

Haroldo Cesar de Oliveira1,2, Maria Candida Monteiro1, Suélen Andreia Rossi1, Javier Pemán3,4, Alba Ruiz-Gaitán4, Maria José Soares Mendes-Giannini2, Emilia Mellado1* and Oscar Zaragoza1*
  • 1Mycology Reference Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III, Madrid, Spain
  • 2Laboratório de Micologia Clínica, Departamento de Análises Clínicas, Faculdade de Ciências Farmacêuticas, Universidade Estadual Paulista (UNESP), Araraquara, Brazil
  • 3Hospital Universitari i Politécnic La Fe, Valencia, Spain
  • 4Instituto de Investigación Sanitaria La Fe, Valencia, Spain

Candida auris is an emerging fungal pathogen of great concern among the scientific community because it is causing an increasing number of hospital outbreaks of difficult management worldwide. In addition, isolates from this species frequently present reduced susceptibility to azole and echinocandin drugs. For this reason, it is necessary to develop new antifungal strategies to better control the disease caused by this yeast. In this work, we screened drugs from the Prestwick chemical library, which contains 1,280 off-patent compounds that are already approved by the Food and Drug Administration, with the aim of identifying molecules with antifungal activity against C. auris. In an initial screening, we looked for drugs that inhibited the growth of three different C. auris strains and found 27 of them which it did so. Ten active compounds were selected to test the susceptibility profile by using the EUCAST protocol. Antifungal activity was confirmed for seven drugs with MICs ranging from 0.5 to 64 mg/L. Some of these drugs were also tested in combination with voriconazole and anidulafungin at sub-inhibitory concentrations. Our results suggest synergistic interactions between suloctidil and voriconazole with fractional inhibitory concentration index (FICI) values of 0.11 to 0.5 and between ebselen and anidulafungin (FICI, 0.12 to 0.44). Our findings indicate that drug repurposing could be a viable alternative to managing infections by C. auris.


Infections caused by fungi are an increasing threat for immunosuppressed patient, and their incidence has risen in the last few decades (Low and Rotstein, 2011; Brown et al., 2012; Pilmis et al., 2016). Invasive fungal diseases (IFDs) have a high associated mortality rate and economic cost (Dignani, 2014; Drgona et al., 2014). The fungal pathogens with a higher prevalence in clinical settings belong to Candida and Aspergillus genera (Sanglard, 2016). However, the changing epidemiology of the fungal pathogenic species is one of the main challenges in clinical mycology. This variation is mainly caused by the massive use of antifungals, especially azoles and echinocandins, which have caused the emergence of species with reduced susceptibility to these antifungals (such as Candida krusei, C. glabrata, C. parapsilosis, A. terreus, Fusarium, Scedosporium, and Lomentospora) (Arendrup and Perlin, 2014; Berkow and Lockhart, 2017).

Another case that illustrates the epidemiological challenge of IFDs is the recent emergence of Candida auris as pathogen. This species is an ascomycete, closely related to C. haemulonii and C. lusitaniae (Berkow and Lockhart, 2017; Lockhart et al., 2017a), and has been rarely reported as a causative agent of IFDs. But in the last 5 years, this fungus has caused multiple hospital outbreaks worldwide (Calvo et al., 2016; Schelenz et al., 2016; Sharma et al., 2016; Chow et al., 2018; de Cassia Orlandi Sardi et al., 2018; Kohlenberg et al., 2018; Ruiz-Gaitan et al., 2018). The control of these outbreaks has been difficult for several reasons. First, this yeast can easily be misidentified as C. haemulonii or C. parapsilosis in laboratories that do not perform identification through molecular biology or MALDITOF techniques (Chatterjee et al., 2015; Chowdhary et al., 2017). Another concern is the difficulty to control and eradicate the outbreaks from the affected areas. Even rapid patient to patient transmission has been reported (Schwartz and Hammond, 2017). For these reasons, some of these outbreaks have lasted several months or even years until they have been eliminated from the hospitals (Eyre et al., 2018; Ruiz-Gaitan et al., 2018). Concerning C. auris antifungal susceptibility profile, most isolates are intrinsically resistant to fluconazole, and there is also a high resistance rate reported to echinocandins and amphotericin, limiting the treatment options that can be administered to patients (Lockhart et al., 2017b; Sears and Schwartz, 2017; Kordalewska et al., 2018).

The treatment of fungal infections is frequently limited by the appearance of intrinsic and secondary resistance and to the low number of antifungal families available. This is more relevant to C. auris infection treatment, requiring the design of new therapeutic strategies. In the last few years, drug repurposing of “off-patent” drugs has become a feasible alternative to developing new treatments for invasive fungal diseases. This strategy offers important advantages compared to the development of new drugs, such as lower costs and shorter time required to implement use. In the case of fungal pathogens, drug repurposing has been successfully used to identify off-patent compounds against C. albicans and Cryptococcus neoformans (Butts et al., 2013; Siles et al., 2013; Kim et al., 2015; Wiederhold et al., 2017; Nixon et al., 2018). In this work, we have attempted to identify new drugs that present antifungal activity against C. auris. We have screened the Prestwick Chemical Library, which contains 1,280 off-patent compounds approved by the FDA for the treatment of many different diseases. We found several compounds that could be considered as alternative options to inhibit the growth of C. auris alone or in combination with antifungals, confirming that the repurposing of off-patent drugs is a promising approach to finding antimicrobial molecules.

Materials and Methods

Isolates and Culture Conditions

In this work we used five C. auris strains isolated in Spain and kept at Mycology Reference Laboratory: CL-10093, CL-9998, CL-10021, CL-10013, and CL-10030; one C. auris from Japan: JCM 15448 (Satoh et al., 2009); and another strain isolated from Korea: KCTC 17810 (Kim et al., 2009). All the isolates were propagated in agar Saboraud plates incubated at 30°C.

Antifungal Susceptibility Testing

Antifungal susceptibility testing was performed using the broth microdilution method described by the European Committee on Antimicrobial Susceptibility Testing, EUCAST (E.Def 7.3.1 reference method) (Arendrup et al., 2016). The antifungal agents tested and the range of concentrations used were: amphotericin B (AmB) (0.03–16 mg/L) (Sigma Aldrich Quimica, Madrid, Spain), flucytosine (5FC) (0.12–64 mg/L) (ICN Pharmaceuticals, Orsay, France), fluconazole (FCZ) (0.12–64 mg/L) (Pfizer SA, Madrid, Spain), itraconazole (ITZ) (0.015–8 mg/L) (Janssen Pharmaceutical S.A., Madrid, Spain), voriconazole (VCZ) (0.015–8 mg/L) (Pfizer, S.A., Madrid, Spain), posaconazole (PSZ) (0.015–8 mg/L) (Schering-plow, Madrid, Spain), isavuconazole (IVZ) (0.015–8 mg/L) (Astellas Pharma Inc., Tokyo, Japan), caspofungin (CAS) (0.03–16 mg/L) (Merck Research Laboratories, Rahway, N.J), micafungin (MCF) (0.004–2 mg/L) (Astellas Pharma Inc., Tokyo, Japan), and anidulafungin (ANID) (0.007–4 mg/L) (Merck & Com, Inc, NJ, USA). Candida auris isolates were cultivated in agar Sabouraud plates at 35°C for 24 h and an inoculum at 1–5 × 105 cells/mL was prepared in distillated water. Then, 100 μL of this inoculum were added to the library plates (final inoculum = 0.5–2.5 × 105 cells/mL). The plates were incubated at 35°C and growth inhibition was evaluated after 24 h of incubation by measuring the optical density at 530 nm in a spectrophotometer. The minimal inhibitory concentration (MIC) was defined as the concentration that inhibited at least 50% of C. auris growth, except for AmB, for which MIC evaluated 90% of growth inhibition.

Screening for Active Drugs Against C. auris

The Prestwick Library was purchased from Prestwick Chemical. The library is composed of 1,280 off-patent drugs in 96-well plates approved by the Food and Drug Administration (FDA) and European Medicines Agency (EMA). Each compound was prepared at 10 mM in dimethyl sulfoxide (DMSO). For the screening, each drug from the library was diluted to a final concentration of 50 μM in RPMI medium containing 2% glucose buffered at pH 7.0 with 165 mM MOPS. In each plate, growth and sterility controls were added. Candida auris inocula were suspended in distilled water as described above. The plates were incubated for 24 h at 35°C without shaking and the growth was evaluated by spectrophotometric readings at 530 nm. Active compounds against C. auris were determined as the ones that inhibited at least 50% of growth. This primary screening was performed using three C. auris strains with different geographical origin: CL-10093, JCM 15448, and KCTC 17810.

Minimal Inhibitory Concentration of Active Drugs Against C. auris

The MIC of active compounds against C. auris was determined following EUCAST methodology (Arendrup et al., 2016). Antifungal susceptibility plates were prepared with a range of concentrations from 64 to 0.12 mg/L of each compound in RPMI. C. auris inocula were prepared as described using the same concentration to inoculate the plates. The plates were incubated at 35°C and growth inhibition was evaluated after 24 h of incubation by spectrophotometrical readings at 530 nm. The MICs were defined as the concentrations that inhibit at least 50% (MIC50) or 90% (MIC90) of fungal growth.

Checkerboard Assay

The synergism of three active compounds (suloctidil, ciclopirox ethanolamine, and ebselen) with VCZ and ANID was also tested using the checkerboard assay. For this purpose, we used the following drug concentration ranges: the identified compounds ranged from 64 to 0.12 mg/L; VCZ ranged from 8 to 0.12 mg/L; and ANID ranged from 0.5 to 0.007 mg/L. To prepare the plate with the different drug combinations, 50 μL from each compound concentration were mixed with 50 μL of each antifungal concentration. Because the drugs and antifungal stocks were dissolved in DMSO, we ensured that, the DMSO concentration did not exceed 1% in the assay plate. Checkerboard plates were inoculated with 100 μL C. auris inoculum prepared as described above. Plates were incubated for 24 h at 35°C without shaking. Yeast growth was measured by spectrophotometric reading at 530 nm. The Fractional Inhibitory Concentration index (FICI) was calculated according to the equation: ΣFIC = FIC (Compounds) + FIC (VCZ or ANID). The FIC index represents the sum of the FICs of each drug tested, where the FIC is determined for each drug by dividing the MIC of each drug when used in combination by the MIC of each drug when used alone (Meletiadis et al., 2010). We considered a synergistic effect when ΣFIC was below 0.5 (White et al., 1996).


Antifungal Susceptibility Profile of C. auris Isolates Against Antifungal Drugs

We first characterized the in vitro antifungal susceptibility of three C. auris strains from different geographical origins. As shown in Table 1, all the strains had reduced susceptibility to all azoles tested, which was more prominent for FCZ and VCZ. In the case of FCZ, all the isolates were fully resistant to this antifungal (≥64 mg/L). These isolates were susceptible to echinocandins, although these antifungals did not fully inhibit the growth of the yeasts. Echinocandins presented a significant trailing growth, which was more prominent after 48 h of incubation (data not shown). All the strains had low MIC values to 5FC (Table 1) and AmB.


Table 1. Antifungal susceptibility test to three C. auris strains.

Identification of Active Compounds Against C. auris

Three clinical C. auris strains (CL-10093, KCTC 17810, and JCM 15448), were used to identify active compounds among the 1,280 compounds from the Prestwick Chemical Library. In this initial screening, we identified 27 active compounds belonging to different classes. Twelve of them inhibited growth ≥90% of the three C. auris strains and 15 inhibited growth more than 50% (Table 2). Among them, we found compounds with different therapeutic effects such as antibacterial, antineoplastic, antihypertensive, antidepressant, anticonvulsant, antiplatelet, anti-inflammatory, antipsychotic, and antipruritic. We also identified 13 antifungal drugs belonging to distinct antifungal classes that were active against the three C. auris strains (Table 3).


Table 2. Active compounds at 0.05 mM against C. auris strains CL-10093, JCM 15448, and KCTC 17810.


Table 3. Antifungal agents active against C. auris strains CL-10093, JCM 15448, and KCTC 17810.

Antifungal Susceptibility Testing of the Selected Compounds

Ten active compounds were selected to analyze their activity against seven C. auris isolates using EUCAST protocol. We confirmed antifungal activity for 7 compounds: trifluoperazine dihydrochloride, suloctidil, ciclopirox ethanolamine, ebselen, tamoxifen citrate, thiethylperazine dimalate, and pyrvinium pamoate. For three compounds [(-)-MK 801 hydrogen maleate, rolipram, and guanadrel sulfate] antifungal activity was not reproduced (Table 4). We did not find noticeable differences in the susceptibility to the compounds when both MIC50 and MIC90 were calculated and compared.


Table 4. MIC50 and MIC90 for the active compounds against C. auris strains.

Synergism Effect of Suloctidil, Ebselen, and Ciclopirox Ethanolamine With Voriconazole and Anidulafungin

Three compounds—suloctidil, ebselen, and ciclopirox ethanolamine—were selected to test synergism with antifungal drugs of clinical use. We did not choose FCZ because the isolates were fully resistant to this drug. VCZ was chosen because, although having high MIC values against C. auris, it still had some in vitro activity. In parallel, synergism with ANID was also tested because echinocandins have become the first treatment option for invasive candidiasis. The three compounds (64–0.12 mg/L) were combined with VCZ (8–0.12 mg/L) and ANID (0.5–0.007 mg/L). The same seven isolates used in the MICs assays were tested in the checkerboard assay. Synergism was evaluated at 24 h and the FIC was calculated for 50 and 75% of growth inhibition.

We found that the combination of suloctidil and VCZ was synergistic against C. auris (FICI values < 0.5 for both 50% and 75% of growth inhibition, Table 5). The MICs for VCZ alone were around 2–4 mg/L, and in combination with different suloctidil concentrations the MICs values decreased to 0.12–1 mg/L (Figure 1).


Table 5. Fractional Inhibitory Concentration Index for the combination of voriconazole with suloctidil against C. auris.


Figure 1. Representative graphs of the synergistic effect of VCZ (ranging concentration: 8–0.12 mg/L) in combination with 2 and 4 mg/L of suloctidil against C. auris strains by checkerboard assay.

In addition, the combination of ebselen and ANID was also synergistic against this fungal pathogen (FICI values < 0.5 for 75% of growth inhibition) (Table 6). C. auris isolates have ANID MIC values of 0.12 mg/L. However, when combined with 0.5 or 1 mg/L of ebselen, we observed an increase in the susceptibility of all the C. auris isolates tested, reaching almost 90% of growth inhibition (Figure 2).


Table 6. Fractional Inhibitory Concentration Index for the combination of anidulafungin with ebselen against C. auris.


Figure 2. Representative graphs of the synergistic effect of AND (ranging concentration: 0.007–0.5 mg/L) in combination with 0.5 and 1 mg/L of ebselen against C. auris strains by checkerboard assay.

No synergism was found when ciclopirox ethanolamine was combined with VCZ or AND.


The first isolation and characterization of C. auris as pathogen was in 2009 when it was isolated from an external ear canal drainage from a patient in Japan (Satoh et al., 2009). However, retrospective studies have demonstrated that this yeast has been the causative agent of diseases since 1996 (Lee et al., 2011). The frequency of detection of C. auris has increased in recent years, revealing a rapid and worldwide emergence of this pathogen (Satoh et al., 2009; Lee et al., 2011; Navalkele et al., 2017; Bidaud et al., 2018; Eyre et al., 2018; Kohlenberg et al., 2018; Ruiz-Gaitan et al., 2018) with a strong potential for nosocomial transmission added to a great capacity for developing multidrug antifungal resistance (Colombo et al., 2017).

The treatment of C. auris infections represents a great challenge due to its antifungal susceptibility profile. The majority of C. auris strains have high MIC values FCZ (>64 mg/L), suggesting intrinsic resistance to this drug (Chowdhary et al., 2017). A great number of isolates also exhibits elevated MICs to VCZ and a few isolates may also be considered resistant to echinocandins (Chowdhary et al., 2016, 2017; Colombo et al., 2017). The mechanisms of antifungal resistance in C. auris remain unknown, although increased tolerance to antifungal drugs may be partly explained because a significant portion of C. auris genome encodes transporters belonging to the ABC and major facilitator superfamilies (Chatterjee et al., 2015). Furthermore, whole genome sequencing of multiple isolates from different geographical regions have demonstrated that the majority of C. auris clinical isolates present amino acid substitutions at the ERG11 gene, which has been associated to fluconazole resistance in other Candida spp (Lockhart et al., 2017b).

The search for new antifungal alternatives is of great importance due to the urgent need to solve the problem of resistance in this pathogen. One strategy is drug repurposing which involves finding new applications for drugs that are already available for use. This approach results in a rapid application at a lower cost compared with the development of a new drug (Corsello et al., 2017). In this work, we describe several off-patent molecules that present antifungal activity against C. auris.

Using this strategy, we initially found 27 compounds with activity against C. auris. Among the active compounds, there were drugs from different therapeutic classes and 13 antifungal drugs (Tables 2, 3). The antifungal activity of seven of them (trifluoperazine dihydrochloride, suloctidil, ciclopirox ethanolamine, ebselen, tamoxifen citrate, thiethylperazine dimalate, pyrvinium pamoate) was confirmed with seven clinical C. auris isolates.

One of the most active compounds was ebselen, which is an anti-inflammatory and antioxidant drug currently under clinical trials for the prevention and treatment of various disorders such as cardiovascular diseases, arthritis, stroke, atherosclerosis, and cancer. Ebselen mimics the activity of glutathione peroxidase and in consequence protects against oxidative damage (Azad and Tomar, 2014). However, in prokaryotes, ebselen inhibits the activity of thioredoxin reductase, leading to an increase in the amount of reactive oxygen species in the cell and decreased viability (Azad and Tomar, 2014). In the case of fungi, ebselen is active against FCZ-resistant C. albicans strains (Billack et al., 2009) and can behave as fungistatic or fungicidal, depending on the concentrations used in the assays. Furthermore, ebselen is at least 10-fold more potent than fluconazole. These authors suggested that the antifungal activity of ebselen could be due to its interaction with the sulfhydryl group of L-cysteine residues within the plasma membrane H+-ATPase (Billack et al., 2009). Other authors have reported that ebselen is active against several fungal species [C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, Cryptococcus neoformans, and C. gattii] at MICs ranging from 0.015 to 2 mg/L (Thangamani et al., 2017; Eyre et al., 2018). In vivo studies using Caenorhabditis elegans as model of infection have shown that ebselen activity is superior to FCZ, 5FC, and AmB. Furthermore, in fungi, ebselen depletes intracellular glutathione levels increasing the production of reactive oxygen species (Thangamani et al., 2017). Our findings are in agreement with the recent work by Wall et al., who found that ebselen has antifungal activity against C. auris and other Candida spp. such as C. lusitaniae, C. krusei, C. albicans, C. dubliniensis, C. parapsilosis, C. tropicalis, and C. glabrata (Wall et al., 2018).

Suloctidil was another compound with important activity against C. auris, with MIC values ranging from 4 to 8 mg/L. Suloctidil is an antiplatelet drug with reported activity against C. albicans and C. neoformans (Butts et al., 2013). Suloctidil is also effective against C. albicans biofilms and inhibits hyphae formation, one of the most important virulence factor of C. albicans (Zeng et al., 2017). By using a chemical-genetic profile approach, it was found that suloctidil interferes with membrane trafficking and vacuolar biogenesis (Spitzer et al., 2011).

We also found that the anthelmintic drug pyrvinium pamoate has a noticeable activity against C. auris, with MIC values ranging from 1 to 4 mg/L against all the strains tested. Pyrvinium pamoate is synergistic with miconazole against C. albicans biofilms (De Cremer et al., 2015). Furthermore, pyrvinium pamoate inhibits the growth of the C. albicans FCZ resistant isochromosome 5L strain, which contains two copies of the left arm of the chromosome 5, a mechanism that confers resistance to FCZ (Chen et al., 2015). More recently, it has been shown that pyrvinium pamoate is active against the black yeast Exophiala dermatitidis strains and exhibits synergy with ITZ, FCZ, and PSZ (Gao et al., 2018).

Ciclopirox ethanolamine, with MICs values ranging from 0.5 to 1 mg/L also presented activity against C. auris. It is thought that it acts by chelating trivalent cations, which induces cell permeability alterations (Gupta and Skinner, 2003). This compound has antifungal activity against several species, including all clinically relevant dermatophytes, molds and yeasts, as well as those with reduced susceptibility to azoles, such as C. glabrata, C. krusei, and C. guilliermondii (Niewerth et al., 2003).

In addition to the search for new antifungal compounds, another important tool to fight resistant fungal infection is to improve the action of the known antifungal drugs currently used in therapy. One approach is finding molecules or drugs that act synergistically with known antifungal drugs. In example, synergy between micafungin and voriconazole has been found with multiple C. auris strains (Fakhim et al., 2017).

We evaluated the synergism activity of three of the screened compounds, ebselen, suloctidil, and ciclopirox ethanolamine with two antifungal drugs, voriconazole and anidulafungin.

Ebselen only showed a moderate synergism with ANID. In our results, ANID at higher concentrations >0.12 mg/L produced a growth inhibition of 60–70%, and the addition of ebselen increased this inhibition to >90%. Wall et al. assayed the synergism of ebselen with FCZ, AmB, and caspofungin against planktonic cells and biofilm from C. auris and C. albicans and they found that only the combination of ebselen with FCZ was synergic against C. albicans. However, none of the combinations showed synergism against C. auris (Wall et al., 2018).

The only drug that showed synergism with VCZ was Suloctidil. The combination with suloctidil decreased the MIC values for VCZ from 2–4 to 0.12–1 mg/L. Other authors have found that suloctidil is synergistic with FCZ against C. neoformans (Spitzer et al., 2011; Butts et al., 2013). As proposed by Spitzer et al., this combination affects fungal viability in different ways such as increasing fungal cell sensitivity to accumulation of intermediates of the ergosterol pathway, difficulting FCZ export by drug efflux pumps, and inhibiting import of extracellular ergosterol (Spitzer et al., 2011), although these hypothesis have not been fully validated yet.

Our results are in agreement with the recent report by Wall et al. (2018) in which a similar approach was taken to identify several compounds with activity against C. auris. Among the drug hits identified by both studies, four compounds were common: suloctidil, ebselen, pyrvinium pamoate and dimethisoquin hydrochloride, suloctidil and ebselen being the most effective compounds against C. auris (>80% of inhibition). Wall et al. also showed that ebselen has a broad-spectrum antifungal activity, being also able to inhibit biofilms of C. auris and C. neoformans. All these data highlight the potential of ebselen as an antifungal drug. Our study also revealed the effectiveness of different drugs from Wall et al. (2018), probably due to the differences in the concentration of the drugs employed in the screening (50 vs. 20 μM) and to the use of different C. auris strains.

At this point the in vivo use of these drugs cannot be anticipated nor can their associated toxicity, because the concentration required to confer protection against C. auris may be different from the one used in current applications. Besides this limitation, our findings indicate that drug repurposing can be a very important tool for finding active compounds against multi-resistant fungal pathogens. In addition, the use of ebselen or suloctidil in combination with ANID or VCZ, respectively, warrants further consideration.

Data Availability

The datasets generated for this study are available on request to the corresponding author.

Author Contributions

HdO, MM, SR, EM, and OZ conceived and designed the experiments. HdO, MM, and SR performed the experiments. HdO, SR, EM, and OZ analyzed the data. HdO, MG, JP, AR-G, EM, and OZ drafted the manuscript. All authors read and approved the final manuscript.


OZ is funded by grants SAF2014-54336-R and SAF2017-86192-R1 from the Spanish Ministry for Economics, Industry and Competitivity. JP and AR-G are supported by Fondo de Investigación Sanitaria (FIS PI17_01538), EM is supported by Fondo de Investigación Sanitaria (FIS PI15_00019), EM and OZ were also sponsored by Plan Nacional de I+D+i 2013-2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, Spanish Network for Research in Infectious Diseases (REIPI RD16/CIII/0004/0003), co-financed by European Development Regional Fund ERDF A way to achieve Europe, Operative program Intelligent Growth 2014-2020. HdO was funded by postdoctoral fellowship from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP-BEPE 2016/20631-3). MM was funded by Fondo de Investigacion Sanitaria through a Sara Borrell Fellowship (grant CD13/00198). SR was supported by a fellowship from Conselho Nacional de Desenvolvimento Científico e Tecnológico, CNPQ, program Ciências Sem Fronteiras (202436/2015-2).

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Arendrup, M. C., Meletiadis, J., Mouton, J. W., Guinea, J., Cuenca-Estrella, M., Lagrou, K., et al. (2016). EUCAST technical note on isavuconazole breakpoints for Aspergillus, itraconazole breakpoints for Candida and updates for the antifungal susceptibility testing method documents. Clin. Microbiol. Infect. 22, 571 e571–574. doi: 10.1016/j.cmi.2016.01.017

PubMed Abstract | CrossRef Full Text | Google Scholar

Arendrup, M. C., and Perlin, D. S. (2014). Echinocandin resistance: an emerging clinical problem? Curr. Opin. Infect. Dis. 27, 484–492. doi: 10.1097/QCO.0000000000000111

PubMed Abstract | CrossRef Full Text | Google Scholar

Azad, G. K., and Tomar, R. S. (2014). Ebselen, a promising antioxidant drug: mechanisms of action and targets of biological pathways. Mol. Biol. Rep. 41, 4865–4879. doi: 10.1007/s11033-014-3417-x

PubMed Abstract | CrossRef Full Text | Google Scholar

Berkow, E. L., and Lockhart, S. R. (2017). Fluconazole resistance in. Infect. Drug Resist. 10, 237–245. doi: 10.2147/IDR.S118892

PubMed Abstract | CrossRef Full Text | Google Scholar

Bidaud, A. L., Chowdhary, A., and Dannaoui, E. (2018). Candida auris: an emerging drug resistant yeast - A mini-review. J. Mycol. Med. 28, 568–573. doi: 10.1016/j.mycmed.2018.06.007

PubMed Abstract | CrossRef Full Text | Google Scholar

Billack, B., Santoro, M., and Lau-Cam, C. (2009). Growth inhibitory action of ebselen on fluconazole-resistant Candida albicans: role of the plasma membrane H+-ATPase. Microb. Drug Resist. 15, 77–83. doi: 10.1089/mdr.2009.0872

PubMed Abstract | CrossRef Full Text | Google Scholar

Brown, G. D., Denning, D. W., Gow, N. A., Levitz, S. M., Netea, M. G., and White, T. C. (2012). Hidden killers: human fungal infections. Sci. Transl. Med. 4, 165rv113. doi: 10.1126/scitranslmed.3004404

PubMed Abstract | CrossRef Full Text | Google Scholar

Butts, A., DiDone, L., Koselny, K., Baxter, B. K., Chabrier-Rosello, Y., Wellington, M., et al. (2013). A repurposing approach identifies off-patent drugs with fungicidal cryptococcal activity, a common structural chemotype, and pharmacological properties relevant to the treatment of cryptococcosis. Eukaryotic Cell 12, 278–287. doi: 10.1128/EC.00314-12

PubMed Abstract | CrossRef Full Text | Google Scholar

Calvo, B., Melo, A. S., Perozo-Mena, A., Hernandez, M., Francisco, E. C., Hagen, F., et al. (2016). First report of Candida auris in America: clinical and microbiological aspects of 18 episodes of candidemia. J. Infect. 73, 369–374. doi: 10.1016/j.jinf.2016.07.008

PubMed Abstract | CrossRef Full Text | Google Scholar

Chatterjee, S., Alampalli, S. V., Nageshan, R. K., Chettiar, S. T., Joshi, S., and Tatu, U. S. (2015). Draft genome of a commonly misdiagnosed multidrug resistant pathogen Candida auris. BMC Genomics 16:686. doi: 10.1186/s12864-015-1863-z

PubMed Abstract | CrossRef Full Text | Google Scholar

Chen, G., Mulla, W. A., Kucharavy, A., Tsai, H. J., Rubinstein, B., Conkright, J., et al. (2015). Targeting the adaptability of heterogeneous aneuploids. Cell 160, 771–784. doi: 10.1016/j.cell.2015.01.026

PubMed Abstract | CrossRef Full Text | Google Scholar

Chow, N. A., Gade, L., Tsay, S. V., Forsberg, K., Greenko, J. A., Southwick, K. L., et al. (2018). Multiple introductions and subsequent transmission of multidrug-resistant Candida auris in the USA: a molecular epidemiological survey. Lancet Infect. Dis. 18, 1377–1384. doi: 10.1016/S1473-3099(18)30597-8

PubMed Abstract | CrossRef Full Text | Google Scholar

Chowdhary, A., Sharma, C., and Meis, J. F. (2017). Candida auris: a rapidly emerging cause of hospital-acquired multidrug-resistant fungal infections globally. PLoS Pathog. 13:e1006290. doi: 10.1371/journal.ppat.1006290

PubMed Abstract | CrossRef Full Text | Google Scholar

Chowdhary, A., Voss, A., and Meis, J. F. (2016). Multidrug-resistant Candida auris: 'new kid on the block' in hospital-associated infections? J. Hosp. Infect. 94, 209–212. doi: 10.1016/j.jhin.2016.08.004

PubMed Abstract | CrossRef Full Text | Google Scholar

Colombo, A. L., Júnior, J. N. A., and Guinea, J. (2017). Emerging multidrug-resistant Candida species. Curr. Opin. Infect. Dis. 30, 528–538. doi: 10.1097/QCO.0000000000000411

PubMed Abstract | CrossRef Full Text | Google Scholar

Corsello, S. M., Bittker, J. A., Liu, Z., Gould, J., McCarren, P., Hirschman, J. E., et al. (2017). The Drug Repurposing Hub: a next-generation drug library and information resource. Nat. Med. 23, 405–408. doi: 10.1038/nm.4306

PubMed Abstract | CrossRef Full Text | Google Scholar

de Cassia Orlandi Sardi, J., Silva, D. R., Soares Mendes-Giannini, M. J., and Rosalen, P. L. (2018). Candida auris: epidemiology, risk factors, virulence, resistance, and therapeutic options. Microb. Pathog. 125, 116–121. doi: 10.1016/j.micpath.2018.09.014

PubMed Abstract | CrossRef Full Text | Google Scholar

De Cremer, K., Lanckacker, E., Cools, T. L., Bax, M., De Brucker, K., Cos, P., et al. (2015). Artemisinins, new miconazole potentiators resulting in increased activity against Candida albicans biofilms. Antimicrob. Agents Chemother. 59, 421–426. doi: 10.1128/AAC.04229-14

PubMed Abstract | CrossRef Full Text | Google Scholar

Dignani, M. C. (2014). Epidemiology of invasive fungal diseases on the basis of autopsy reports. F1000Prime Rep. 6:81. doi: 10.12703/P6-81

PubMed Abstract | CrossRef Full Text | Google Scholar

Drgona, L., Khachatryan, A., Stephens, J., Charbonneau, C., Kantecki, M., Haider, S., et al. (2014). Clinical and economic burden of invasive fungal diseases in Europe: focus on pre-emptive and empirical treatment of Aspergillus and Candida species. Eur. J. Clin. Microbiol. Infect. Dis. 33, 7–21. doi: 10.1007/s10096-013-1944-3

PubMed Abstract | CrossRef Full Text | Google Scholar

Eyre, D. W., Sheppard, A. E., Madder, H., Moir, I., Moroney, R., Quan, T. P., et al. (2018). A Candida auris outbreak and its control in an intensive care setting. N. Engl. J. Med. 379, 1322–1331. doi: 10.1056/NEJMoa1714373

PubMed Abstract | CrossRef Full Text | Google Scholar

Fakhim, H., Chowdhary, A., Prakash, A., Vaezi, A., Dannaoui, E., Meis, J. F., et al. (2017). In vitro interactions of echinocandins with triazoles against multidrug-resistant Candida auris. Antimicrob. Agents Chemother. 61:e01056-17. doi: 10.1128/AAC.01056-17

PubMed Abstract | CrossRef Full Text | Google Scholar

Gao, L., Sun, Y., He, C., Zeng, T., and Li, M. (2018). Synergy between Pyrvinium Pamoate and Azoles against Exophiala dermatitidis. Antimicrob. Agents Chemother. 62:e02361-17. doi: 10.1128/AAC.02361-17

PubMed Abstract | CrossRef Full Text | Google Scholar

Gupta, A. K., and Skinner, A. R. (2003). Ciclopirox for the treatment of superficial fungal infections: a review. Int. J. Dermatol. 42(Suppl. 1), 3–9. doi: 10.1046/j.1365-4362.42.s1.2.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Kim, K., Zilbermintz, L., and Martchenko, M. (2015). Repurposing FDA approved drugs against the human fungal pathogen, Candida albicans. Ann. Clin. Microbiol. Antimicrob. 14:32. doi: 10.1186/s12941-015-0090-4

PubMed Abstract | CrossRef Full Text | Google Scholar

Kim, M. N., Shin, J. H., Sung, H., Lee, K., Kim, E. C., Ryoo, N., et al. (2009). Candida haemulonii and closely related species at 5 university hospitals in Korea: identification, antifungal susceptibility, and clinical features. Clin. Infect. Dis. 48, e57–61. doi: 10.1086/597108

PubMed Abstract | CrossRef Full Text | Google Scholar

Kohlenberg, A., Struelens, M. J., Monnet, D. L., and Plachouras, D. (2018). Candida auris: epidemiological situation, laboratory capacity and preparedness in European Union and European Economic Area countries, 2013 to 2017. Euro Surveill. 23. doi: 10.2807/1560-7917.ES.2018.23.13.18-00136

PubMed Abstract | CrossRef Full Text

Kordalewska, M., Lee, A., Park, S., Berrio, I., Chowdhary, A., Zhao, Y., et al. (2018). Understanding echinocandin resistance in the emerging pathogen Candida auris. Antimicrob. Agents Chemother. 62, e00238–e00218. doi: 10.1128/AAC.00238-18

PubMed Abstract | CrossRef Full Text | Google Scholar

Lee, W. G., Shin, J. H., Uh, Y., Kang, M. G., Kim, S. H., Park, K. H., et al. (2011). First three reported cases of nosocomial fungemia caused by Candida auris. J. Clin. Microbiol. 49, 3139–3142. doi: 10.1128/JCM.00319-11

PubMed Abstract | CrossRef Full Text | Google Scholar

Lockhart, S. R., Berkow, E. L., Chow, N., and Welsh, R. M. (2017a). Candida auris for the clinical microbiology laboratory: not your grandfather's. Clin. Microbiol. Newslett. 39, 99–103. doi: 10.1016/j.clinmicnews.2017.06.003

PubMed Abstract | CrossRef Full Text | Google Scholar

Lockhart, S. R., Etienne, K. A., Vallabhaneni, S., Farooqi, J., Chowdhary, A., Govender, N. P., et al. (2017b). Simultaneous emergence of multidrug-resistant Candida auris on 3 continents confirmed by whole-genome sequencing and epidemiological analyses. Clin. Infect. Dis. 64, 134–140. doi: 10.1093/cid/ciw691

PubMed Abstract | CrossRef Full Text | Google Scholar

Low, C. Y., and Rotstein, C. (2011). Emerging fungal infections in immunocompromised patients. F1000 Med. Rep. 3:14. doi: 10.3410/M3-14

PubMed Abstract | CrossRef Full Text | Google Scholar

Meletiadis, J., Pournaras, S., Roilides, E., and Walsh, T. J. (2010). Defining fractional inhibitory concentration index cutoffs for additive interactions based on self-drug additive combinations, Monte Carlo simulation analysis, and in vitro-in vivo correlation data for antifungal drug combinations against Aspergillus fumigatus. Antimicrob. Agents Chemother. 54, 602–609. doi: 10.1128/AAC.00999-09

PubMed Abstract | CrossRef Full Text | Google Scholar

Navalkele, B. D., Revankar, S., and Chandrasekar, P. (2017). Candida auris: a worrisome, globally emerging pathogen. Expert Rev. Anti Infect. Ther. 15, 819–827. doi: 10.1080/14787210.2017.1364992

PubMed Abstract | CrossRef Full Text | Google Scholar

Niewerth, M., Kunze, D., Seibold, M., Schaller, M., Korting, H. C., and Hube, B. (2003). Ciclopirox olamine treatment affects the expression pattern of Candida albicans genes encoding virulence factors, iron metabolism proteins, and drug resistance factors. Antimicrob. Agents Chemother. 47, 1805–1817. doi: 10.1128/AAC.47.6.1805-1817.2003

PubMed Abstract | CrossRef Full Text | Google Scholar

Nixon, G. L., McEntee, L., Johnson, A., Farrington, N., Whalley, S., Livermore, J., et al. (2018). Repurposing and reformulation of the antiparasitic agent flubendazole for treatment of cryptococcal meningoencephalitis, a neglected fungal disease. Antimicrob. Agents Chemother. 62:e01909-17. doi: 10.1128/AAC.01909-17

PubMed Abstract | CrossRef Full Text | Google Scholar

Pilmis, B., Puel, A., Lortholary, O., and Lanternier, F. (2016). New clinical phenotypes of fungal infections in special hosts. Clin. Microbiol. Infect. 22, 681–687. doi: 10.1016/j.cmi.2016.05.016

PubMed Abstract | CrossRef Full Text | Google Scholar

Ruiz-Gaitan, A., Moret, A. M., Tasias-Pitarch, M., Aleixandre-Lopez, A. I., Martinez-Morel, H., Calabuig, E., et al. (2018). An outbreak due to Candida auris with prolonged colonisation and candidaemia in a tertiary care European hospital. Mycoses 61, 498–505. doi: 10.1111/myc.12781

PubMed Abstract | CrossRef Full Text | Google Scholar

Sanglard, D. (2016). Emerging threats in antifungal-resistant fungal pathogens. Front. Med. 3:11. doi: 10.3389/fmed.2016.00011

PubMed Abstract | CrossRef Full Text | Google Scholar

Satoh, K., Makimura, K., Hasumi, Y., Nishiyama, Y., Uchida, K., and Yamaguchi, H. (2009). Candida auris sp. nov., a novel ascomycetous yeast isolated from the external ear canal of an inpatient in a Japanese hospital. Microbiol. Immunol. 53, 41–44. doi: 10.1111/j.1348-0421.2008.00083.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Schelenz, S., Hagen, F., Rhodes, J. L., Abdolrasouli, A., Chowdhary, A., Hall, A., et al. (2016). First hospital outbreak of the globally emerging Candida auris in a European hospital. Antimicrob. Resist. Infect. Control 5, 35. doi: 10.1186/s13756-016-0132-5

PubMed Abstract | CrossRef Full Text | Google Scholar

Schwartz, I. S., and Hammond, G. W. (2017). First reported case of multidrug-resistant Candida auris in Canada. Can. Commun. Dis. Rep. 43, 150–153. doi: 10.14745/ccdr.v43i78a02

PubMed Abstract | CrossRef Full Text | Google Scholar

Sears, D., and Schwartz, B. S. (2017). Candida auris: an emerging multidrug-resistant pathogen. Int. J. Infect. Dis. 63, 95–98. doi: 10.1016/j.ijid.2017.08.017

PubMed Abstract | CrossRef Full Text | Google Scholar

Sharma, C., Kumar, N., Pandey, R., Meis, J. F., and Chowdhary, A. (2016). Whole genome sequencing of emerging multidrug resistant Candida auris isolates in India demonstrates low genetic variation. New Microbes New Infect. 13, 77–82. doi: 10.1016/j.nmni.2016.07.003

PubMed Abstract | CrossRef Full Text | Google Scholar

Siles, S. A., Srinivasan, A., Pierce, C. G., Lopez-Ribot, J. L., and Ramasubramanian, A. K. (2013). High-throughput screening of a collection of known pharmacologically active small compounds for identification of Candida albicans biofilm inhibitors. Antimicrob. Agents Chemother. 57, 3681–3687. doi: 10.1128/AAC.00680-13

PubMed Abstract | CrossRef Full Text | Google Scholar

Spitzer, M., Griffiths, E., Blakely, K. M., Wildenhain, J., Ejim, L., Rossi, L., et al. (2011). Cross-species discovery of syncretic drug combinations that potentiate the antifungal fluconazole. Mol. Syst. Biol. 7, 499. doi: 10.1038/msb.2011.31

PubMed Abstract | CrossRef Full Text | Google Scholar

Thangamani, S., Eldesouky, H. E., Mohammad, H., Pascuzzi, P. E., Avramova, L., Hazbun, T. R., et al. (2017). Ebselen exerts antifungal activity by regulating glutathione (GSH) and reactive oxygen species (ROS) production in fungal cells. Biochim. Biophys. Acta 1861(1 Pt A), 3002–3010. doi: 10.1016/j.bbagen.2016.09.029

PubMed Abstract | CrossRef Full Text | Google Scholar

Wall, G., Chaturvedi, A. K., Wormley, F. L., Wiederhold, N. P., Patterson, H. P., Patterson, T. F., et al. (2018). Screening a repurposing library for inhibitors of multi-drug resistant Candida auris identifies ebselen as a repositionable candidate for antifungal drug development. Antimicrob. Agents Chemother. 62, e01084–e01018. doi: 10.1128/AAC.01084-18

PubMed Abstract | CrossRef Full Text | Google Scholar

White, R. L., Burgess, D. S., Manduru, M., and Bosso, J. A. (1996). Comparison of three different in vitro methods of detecting synergy: time-kill, checkerboard, and E test. Antimicrob. Agents Chemother. 40, 1914–1918

PubMed Abstract | Google Scholar

Wiederhold, N. P., Patterson, T. F., Srinivasan, A., Chaturvedi, A. K., Fothergill, A. W., Wormley, F. L., et al. (2017). Repurposing auranofin as an antifungal: in vitro activity against a variety of medically important fungi. Virulence 8, 138–142. doi: 10.1080/21505594.2016.1196301

PubMed Abstract | CrossRef Full Text | Google Scholar

Zeng, B., Li, J., Wang, Y., Chen, P., Wang, X., Cui, J., et al. (2017). In vitro and in vivo effects of suloctidil on growth and biofilm formation of the opportunistic fungus Candida albicans. Oncotarget 8, 69972–69982. doi: 10.18632/oncotarget.19542

PubMed Abstract | CrossRef Full Text | Google Scholar

Keywords: Candida auris, antifungals, drug repurposing, synergism, multiresistance

Citation: de Oliveira HC, Monteiro MC, Rossi SA, Pemán J, Ruiz-Gaitán A, Mendes-Giannini MJS, Mellado E and Zaragoza O (2019) Identification of Off-Patent Compounds That Present Antifungal Activity Against the Emerging Fungal Pathogen Candida auris. Front. Cell. Infect. Microbiol. 9:83. doi: 10.3389/fcimb.2019.00083

Received: 20 November 2018; Accepted: 11 March 2019;
Published: 02 April 2019.

Edited by:

Priya Uppuluri, University of California, Los Angeles, United States

Reviewed by:

Rasoul Mohammadi, Isfahan University of Medical Sciences, Iran
Hadis Jafarian, Shiraz University of Medical Sciences, Iran

Copyright © 2019 de Oliveira, Monteiro, Rossi, Pemán, Ruiz-Gaitán, Mendes-Giannini, Mellado and Zaragoza. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Emilia Mellado,
Oscar Zaragoza,

Present Address: Suélen Andreia Rossi, Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil