The Emergence of Azole Resistance in Candida parapsilosis isolates Causing Systemic Candidosis

ABSTRACT Among emerging non-albicans Candida species, Candida parapsilosis is of particular concern as a cause of nosocomial bloodstream infections in neonatal and intensive care unit patients. While fluconazole and echinocandins are considered effective treatments for such infections, recent reports of fluconazole and echinocandin resistance in C. parapsilosis indicate a growing problem. The present study describes a novel mechanism of antifungal resistance in this organism affecting susceptibility to azole and echinocandin antifungals in a clinical isolate obtained from a patient with prosthetic valve endocarditis. Transcriptome analysis indicated differential expression of several genes in the resistant isolate, including upregulation of ergosterol biosynthesis pathway genes ERG2, ERG5, ERG6, ERG11, ERG24, ERG25, and UPC2. Whole-genome sequencing revealed that the resistant isolate possessed an ERG3 mutation resulting in a G111R amino acid substitution. Sterol profiles indicated a reduction in sterol desaturase activity as a result of this mutation. Replacement of both mutant alleles in the resistant isolate with the susceptible isolate's allele restored wild-type susceptibility to all azoles and echinocandins tested. Disruption of ERG3 in the susceptible and resistant isolates resulted in a loss of sterol desaturase activity, high-level azole resistance, and an echinocandin-intermediate to -resistant phenotype. While disruption of ERG3 in C. albicans resulted in azole resistance, echinocandin MICs, while elevated, remained within the susceptible range. This work demonstrates that the G111R substitution in Erg3 is wholly responsible for the altered azole and echinocandin susceptibilities observed in this C. parapsilosis isolate and is the first report of an ERG3 mutation influencing susceptibility to the echinocandins.

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Virulence factors, antifungal susceptibility and molecular mechanisms of azole resistance among Candida parapsilosis complex isolates recovered from clinical specimens

Journal of Biomedical Science ◽

10.1186/s12929-017-0376-2 ◽

2017 ◽

Vol 24 (1) ◽

Cited By ~ 15

Author(s):

Sourour Neji ◽

Ines Hadrich ◽

Houaida Trabelsi ◽

Salma Abbes ◽

Fatma Cheikhrouhou ◽

...

Keyword(s):

Virulence Factors ◽

Molecular Mechanisms ◽

Candida Parapsilosis ◽

Antifungal Susceptibility ◽

Azole Resistance ◽

Clinical Specimens ◽

Candida Parapsilosis Complex

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Fluconazole and Voriconazole Resistance in Candida parapsilosis Is Conferred by Gain-of-Function Mutations inMRR1Transcription Factor Gene

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00842-15 ◽

2015 ◽

Vol 59 (10) ◽

pp. 6629-6633 ◽

Cited By ~ 24

Author(s):

Joana Branco ◽

Ana P. Silva ◽

Raquel M. Silva ◽

Ana Silva-Dias ◽

Cidália Pina-Vaz ◽

...

Keyword(s):

Transcription Factor ◽

Molecular Mechanisms ◽

Candida Parapsilosis ◽

Bloodstream Infections ◽

Azole Resistance ◽

Transcription Factor Gene ◽

Gain Of Function ◽

Content Type ◽

Factor Gene ◽

Resistant Strains

ABSTRACTCandida parapsilosisis the second most prevalent fungal agent causing bloodstream infections. Nevertheless, there is little information about the molecular mechanisms underlying azole resistance in this species. Mutations (G1747A, A2619C, and A3191C) in theMRR1transcription factor gene were identified in fluconazole- and voriconazole-resistant strains. Independent expression ofMRR1genes harboring these mutations showed that G1747A (G583R) and A2619C (K873N) are gain-of-function mutations responsible for azole resistance, the first described inC. parapsilosis.

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Impact of ERG3 mutations and expression of ergosterol genes controlled by UPC2 and NDT80 in Candida parapsilosis azole resistance

Clinical Microbiology and Infection ◽

10.1016/j.cmi.2017.02.002 ◽

2017 ◽

Vol 23 (8) ◽

pp. 575.e1-575.e8 ◽

Cited By ~ 17

Author(s):

J. Branco ◽

M. Ola ◽

R.M. Silva ◽

E. Fonseca ◽

N.C. Gomes ◽

...

Keyword(s):

Candida Parapsilosis ◽

Azole Resistance

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Multidrug Transporters and Alterations in Sterol Biosynthesis Contribute to Azole Antifungal Resistance in Candida parapsilosis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01358-15 ◽

2015 ◽

Vol 59 (10) ◽

pp. 5942-5950 ◽

Cited By ~ 35

Author(s):

Elizabeth L. Berkow ◽

Kayihura Manigaba ◽

Josie E. Parker ◽

Katherine S. Barker ◽

Stephen L. Kelly ◽

...

Keyword(s):

Candida Parapsilosis ◽

Transcriptional Regulators ◽

Comprehensive Analysis ◽

Sterol Biosynthesis ◽

Azole Resistance ◽

Drug Transporter ◽

Content Type ◽

Multidrug Transporters ◽

Activating Mutations ◽

Genes Encoding

ABSTRACTWhile much is known concerning azole resistance inCandida albicans, considerably less is understood aboutCandida parapsilosis, an emerging species ofCandidawith clinical relevance. We conducted a comprehensive analysis of azole resistance in a collection of resistantC. parapsilosisclinical isolates in order to determine which genes might play a role in this process within this species. We examined the relative expression of the putative drug transporter genesCDR1andMDR1and that ofERG11. In isolates overexpressing these genes, we sequenced the genes encoding their presumed transcriptional regulators,TAC1,MRR1, andUPC2, respectively. We also sequenced the sterol biosynthesis genesERG3andERG11in these isolates to find mutations that might contribute to this phenotype in thisCandidaspecies. Our findings demonstrate that the putative drug transporters Cdr1 and Mdr1 contribute directly to azole resistance and suggest that their overexpression is due to activating mutations in the genes encoding their transcriptional regulators. We also observed that the Y132F substitution inERG11is the only substitution occurring exclusively among azole-resistant isolates, and we correlated this with specific changes in sterol biosynthesis. Finally, sterol analysis of these isolates suggests that other changes in sterol biosynthesis may contribute to azole resistance inC. parapsilosis.

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Triazole Evolution of Candida parapsilosis Results in Cross-Resistance to Other Antifungal Drugs, Influences Stress Responses, and Alters Virulence in an Antifungal Drug-Dependent Manner

mSphere ◽

10.1128/msphere.00821-20 ◽

2020 ◽

Vol 5 (5) ◽

Author(s):

Csaba Papp ◽

Flóra Bohner ◽

Katica Kocsis ◽

Mónika Varga ◽

András Szekeres ◽

...

Keyword(s):

Amino Acid ◽

Candida Parapsilosis ◽

Treatment Strategies ◽

Antifungal Drugs ◽

Antifungal Treatment ◽

Cross Resistance ◽

Azole Resistance ◽

Resistance Development ◽

Content Type ◽

Invasive Infections

ABSTRACT The number of invasive infections caused by Candida species is increasing worldwide. The incidence of candidiasis cases caused by non-albicans Candida species, such as Candida parapsilosis, is also increasing, and non-albicans Candida species are currently responsible for more invasive infections than C. albicans. Additionally, while the development of azole resistance during invasive disease with C. albicans remains uncommon, azole-resistant C. parapsilosis strains are frequently isolated in the hospital setting. In this study, we applied direct selection to generate azole-adapted and azole-evolved C. parapsilosis strains in order to examine the effect of azole resistance development on fungal viability and pathogenesis progression. Depending on the drug applied, the different evolved strains developed distinct cross-resistance patterns: the fluconazole-evolved (FLUEVO) and voriconazole-evolved (VOREVO) strains gained resistance to fluconazole and voriconazole only, while posaconazole evolution resulted in cross-resistance to all azoles and the posaconazole-evolved (POSEVO) strains showed higher echinocandin MIC values than the FLUEVO and VOREVO strains. Whole-genome sequencing results identified the development of different resistance mechanisms in the evolved strains: the FLUEVO and VOREVO strains harbored amino acid substitutions in Mrr1p (A808T and N394Y, respectively), and the POSEVO strain harbored an amino acid change in Erg3p (D14Y). By revealing increased efflux pump activity in both the FLUEVO and the VOREVO strains, along with the altered sterol composition of the POSEVO strain, we now highlight the impact of the above-mentioned amino acid changes in C. parapsilosis azole resistance development. We further revealed that the virulence of this species was only slightly or partially affected by fluconazole and voriconazole adaptation, while it significantly decreased after posaconazole adaptation. Our results suggest that triazole adaptation can result in azole cross-resistance and that this process may also result in virulence alterations in C. parapsilosis, depending on the applied drug. IMPORTANCE Candida parapsilosis causes life-threatening fungal infections. In the last 2 decades, the increasing number of azole-resistant C. parapsilosis clinical isolates has been attributable to the overuse and misuse of fluconazole, the first-line antifungal agent most commonly used in several countries. To date, the range of applicable antifungal drugs is limited. As a consequence, it is essential to understand the possible mechanisms of antifungal resistance development and their effect on virulence in order to optimize antifungal treatment strategies in the clinical setting. Our results revealed that the prolonged exposure to azoles resulted not only in azole resistance but also in cross-resistance development. Our data further indicate that resistance development may occur through different mechanisms that can also alter the virulence of C. parapsilosis. These results highlight the consequences of prolonged drug usage and suggest the need for developing alternative antifungal treatment strategies in clinical practice.

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