Dataset Information

First fluconazole-resistant Candida auris isolated from fungal otitis in Iran.

ABSTRACT:

Background and purpose

Candida auris, as a new characterized pathogenic yeast, has attracted remarkable attention in the recent decade due to its rapid global emergence and multidrug resistance traits. This unique species is able to cause nosocomial outbreaks and tolerate adverse conditions; however, it has been mostly misidentified by conventional methods.

Case report

This report aimed to describe the first fluconazole-resistant case of C. auris otitis in an immunocompetent patient in Iran. The isolate showed minimum inhibitory concentration of ≥ 32 μg/ml for fluconazole; however, the patient was treated with topical clotrimazole and miconazole with no recurrence.

Conclusion

This was the second strain of C. auris isolated from otitis in Iran which was fluconazole-resistant, unlike the first Iranian isolate.

SUBMITTER: Taghizadeh Armaki M

PROVIDER: S-EPMC8443880 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature

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First fluconazole-resistant <i>Candida auris</i> isolated from fungal otitis in Iran.

Taghizadeh Armaki Mojtaba M Mahdavi Omran Saeid S Kiakojuri Keyvan K Khojasteh Shaghayegh S Jafarzadeh Jalal J Tavakoli Mahin M Badali Hamid H Haghani Iman I Shokohi Tahereh T Taghi Hedayati Mohammad M Abastabar Mahdi M

Current medical mycology 20210301 1

<h4>Background and purpose</h4><i>Candida auris</i>, as a new characterized pathogenic yeast, has attracted remarkable attention in the recent decade due to its rapid global emergence and multidrug resistance traits. This unique species is able to cause nosocomial outbreaks and tolerate adverse conditions; however, it has been mostly misidentified by conventional methods.<h4>Case report</h4>This report aimed to describe the first fluconazole-resistant case of <i>C. auris</i> otitis in an immunoc ...[more]

PMID: 34553098

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Project description:The recently emerged pathogenic yeast Candida auris is a major concern for human health, because it is easily transmissible, difficult to eradicate from hospitals, and highly drug resistant. Most C. auris isolates are resistant to the widely used antifungal drug fluconazole due to mutations in the target enzyme Erg11 and high activity of efflux pumps, such as Cdr1. In the well-studied, distantly related yeast Candida albicans, overexpression of drug efflux pumps also is a major mechanism of acquired fluconazole resistance and caused by gain-of-function mutations in the zinc cluster transcription factors Mrr1 and Tac1. In this study, we investigated a possible involvement of related transcription factors in efflux pump expression and fluconazole resistance of C. auris The C. auris genome contains three genes encoding Mrr1 homologs and two genes encoding Tac1 homologs, and we generated deletion mutants lacking these genes in two fluconazole-resistant strains from clade III and clade IV. Deletion of TAC1b decreased the resistance to fluconazole and voriconazole in both strain backgrounds, demonstrating that the encoded transcription factor contributes to azole resistance in C. auris strains from different clades. CDR1 expression was not or only minimally affected in the mutants, indicating that Tac1b can confer increased azole resistance by a CDR1-independent mechanism.IMPORTANCE Candida auris is a recently emerged pathogenic yeast that within a few years after its initial description has spread all over the globe. C. auris is a major concern for human health, because it can cause life-threatening systemic infections, is easily transmissible, and is difficult to eradicate from hospital environments. Furthermore, C. auris is highly drug resistant, especially against the widely used antifungal drug fluconazole. Mutations in the drug target and high activity of efflux pumps are associated with azole resistance, but it is not known how drug resistance genes are regulated in C. auris We have investigated the potential role of several candidate transcriptional regulators in the intrinsic fluconazole resistance of C. auris and identified a transcription factor that contributes to the high resistance to fluconazole and voriconazole of two C. auris strains from different genetic clades, thereby providing insight into the molecular basis of drug resistance of this medically important yeast.

Project description:Candida auris has emerged as a multidrug-resistant pathogen of great clinical concern. Approximately 90% of clinical C. auris isolates are resistant to fluconazole, the most commonly prescribed antifungal agent, and yet it remains unknown what mechanisms underpin this fluconazole resistance. To identify novel mechanisms contributing to fluconazole resistance in C. auris, fluconazole-susceptible C. auris clinical isolate AR0387 was passaged in media supplemented with fluconazole to generate derivative strains which had acquired increased fluconazole resistance in vitro Comparative analyses of comprehensive sterol profiles, [3H]fluconazole uptake, sequencing of C. auris genes homologous to genes known to contribute to fluconazole resistance in other species of Candida, and relative expression levels of C. aurisERG11, CDR1, and MDR1 were performed. All fluconazole-evolved derivative strains were found to have acquired mutations in the zinc-cluster transcription factor-encoding gene TAC1B and to show a corresponding increase in CDR1 expression relative to the parental clinical isolate, AR0387. Mutations in TAC1B were also identified in a set of 304 globally distributed C. auris clinical isolates representing each of the four major clades. Introduction of the most common mutation found among fluconazole-resistant clinical isolates of C. auris into fluconazole-susceptible isolate AR0387 was confirmed to increase fluconazole resistance by 8-fold, and the correction of the same mutation in a fluconazole-resistant isolate, AR0390, decreased fluconazole MIC by 16-fold. Taken together, these data demonstrate that C. auris can rapidly acquire resistance to fluconazole in vitro and that mutations in TAC1B significantly contribute to clinical fluconazole resistance.IMPORTANCECandida auris is an emerging multidrug-resistant pathogen of global concern, known to be responsible for outbreaks on six continents and to be commonly resistant to antifungals. While the vast majority of clinical C. auris isolates are highly resistant to fluconazole, an essential part of the available antifungal arsenal, very little is known about the mechanisms contributing to resistance. In this work, we show that mutations in the transcription factor TAC1B significantly contribute to clinical fluconazole resistance. These studies demonstrated that mutations in TAC1B can arise rapidly in vitro upon exposure to fluconazole and that a multitude of resistance-associated TAC1B mutations are present among the majority of fluconazole-resistant C. auris isolates from a global collection and appear specific to a subset of lineages or clades. Thus, identification of this novel genetic determinant of resistance significantly adds to the understanding of clinical antifungal resistance in C. auris.