Occurrence of Clavispora lusitaniae, the teleomorph of Candida lusitaniae, among clinical isolates.

ABSTRACT Candida lusitaniae is an emerging human pathogen that, unlike other fungal pathogens, frequently develops resistance to the commonly used antifungal agent amphotericin B. Amphotericin B is a member of the polyene class of antifungal drugs, which impair fungal cell membrane integrity. Here we analyzed mechanisms contributing to amphotericin B resistance in C. lusitaniae. Sensitivity to polyenes in the related fungi Saccharomyces cerevisiae and Candida albicans requires the ergosterol biosynthetic gene ERG6. In an effort to understand the mechanisms contributing to amphotericin B resistance in C. lusitaniae, we isolated the ERG6 gene and created a C. lusitaniae erg6Δ strain. This mutant strain exhibited a growth defect, was resistant to amphotericin B, and was hypersensitive to other sterol inhibitors. Based on the similarities between the phenotypes of the erg6Δ mutant and clinical isolates of C. lusitaniae resistant to amphotericin B, we analyzed ERG6 expression levels and ergosterol content in multiple clinical isolates. C. lusitaniae amphotericin B-resistant isolates were found to have increased levels of ERG6 transcript as well as reduced ergosterol content. These changes suggest that another gene in the ergosterol biosynthetic pathway could be mutated or misregulated. Further transcript analysis showed that expression of the ERG3 gene, which encodes C-5 sterol desaturase, was reduced in two amphotericin B-resistant isolates. Our findings reveal that mutation or altered expression of ergosterol biosynthetic genes can result in resistance to amphotericin B in C. lusitaniae.

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Flucytosine-Fluconazole Cross-Resistance in Purine-Cytosine Permease-Deficient Candida lusitaniae Clinical Isolates: Indirect Evidence of a Fluconazole Uptake Transporter

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.47.6.2062.2003 ◽

2003 ◽

Vol 47 (6) ◽

pp. 2062-2062

Author(s):

Thierry Noël ◽

Fabienne François ◽

Patrick Paumard ◽

Christiane Chastin ◽

Daniel Brèthes ◽

...

Keyword(s):

Indirect Evidence ◽

Clinical Isolates ◽

Cross Resistance ◽

Candida Lusitaniae

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Flucytosine-Fluconazole Cross-Resistance in Purine-Cytosine Permease-Deficient Candida lusitaniae Clinical Isolates: Indirect Evidence of a Fluconazole Uptake Transporter

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.47.4.1275-1284.2003 ◽

2003 ◽

Vol 47 (4) ◽

pp. 1275-1284 ◽

Cited By ~ 26

Author(s):

Thierry Noël ◽

Fabienne François ◽

Patrick Paumard ◽

Christiane Chastin ◽

Daniel Brèthes ◽

...

Keyword(s):

In Vitro Selection ◽

Single Gene ◽

Resistance Mechanism ◽

Cytosine Deaminase ◽

Indirect Evidence ◽

Clinical Isolates ◽

Cross Resistance ◽

Recessive Mutation ◽

Candida Lusitaniae

ABSTRACT An unusual interaction between flucytosine and fluconazole was observed when a collection of 60 Candida lusitaniae clinical isolates was screened for cross-resistance. Among eight isolates resistant to flucytosine (MIC ≥ 128 μg/ml) and susceptible to fluconazole (0.5 < MIC < 2 μg/ml), four became flucytosine-fluconazole cross resistant when both antifungals were used simultaneously. Fluconazole resistance occurred only in the presence of high flucytosine concentrations, and the higher the fluconazole concentration used, the greater the flucytosine concentration necessary to trigger the cross-resistance. When the flucytosine- and fluconazole-resistant cells were grown in the presence of fluconazole alone, the cells reversed to fluconazole susceptibility. Genetic analyses of the progeny from crosses between resistant and sensitive isolates showed that resistance to flucytosine was derived from a recessive mutation in a single gene, whereas cross-resistance to fluconazole seemed to vary like a quantitative trait. We further demonstrated that the four clinical isolates were susceptible to 5-fluorouracil and that cytosine deaminase activity was unaffected. Kinetic transport studies with [14C]flucytosine showed that flucytosine resistance was due to a defect in the purine-cytosine permease. Our hypothesis was that extracellular flucytosine would subsequently behave as a competitive inhibitor of fluconazole uptake transport. Finally, in vitro selection of spontaneous and induced mutants indicated that such a cross-resistance mechanism could also affect other Candida species, including C. albicans, C. tropicalis, and C. glabrata. This is the first report of a putative fluconazole uptake transporter in Candida species and of a possible resistance mechanism associated with a deficiency in the uptake of this drug.

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Nonsense and Missense Mutations in FCY2 and FCY1 Genes Are Responsible for Flucytosine Resistance and Flucytosine-Fluconazole Cross-Resistance in Clinical Isolates of Candida lusitaniae

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00880-08 ◽

2009 ◽

Vol 53 (7) ◽

pp. 2982-2990 ◽

Cited By ~ 34

Author(s):

Martine Florent ◽

Thierry Noël ◽

Gwenaël Ruprich-Robert ◽

Bruno Da Silva ◽

Valérie Fitton-Ouhabi ◽

...

Keyword(s):

Nonsense Mutation ◽

Molecular Mechanisms ◽

Antifungal Susceptibility ◽

Cytosine Deaminase ◽

Clinical Isolates ◽

Cross Resistance ◽

Nucleotide Sequencing ◽

Missense Mutations ◽

Wild Type ◽

Candida Lusitaniae

ABSTRACT The aim of this work was to elucidate the molecular mechanisms of flucytosine (5FC) resistance and 5FC/fluconazole (FLC) cross-resistance in 11 genetically and epidemiologically unrelated clinical isolates of Candida lusitaniae. We first showed that the levels of transcription of the FCY2 gene encoding purine-cytosine permease (PCP) in the isolates were similar to that in the wild-type strain, 6936. Nucleotide sequencing of the FCY2 alleles revealed that 5FC and 5FC/FLC resistance could be correlated with a cytosine-to-thymine substitution at nucleotide 505 in the fcy2 genes of seven clinical isolates, resulting in a nonsense mutation and in a putative nonfunctional truncated PCP of 168 amino acids. Reintroducing a FCY2 wild-type allele at the fcy2 locus of a ura3 auxotrophic strain derived from the clinical isolate CL38 fcy2(C505T) restored levels of susceptibility to antifungals comparable to those of the wild-type strains. In the remaining four isolates, a polymorphic nucleotide was found in FCY1 where the nucleotide substitution T26C resulted in the amino acid replacement M9T in cytosine deaminase. Introducing this mutated allele into a 5FC- and 5FC/FLC-resistant fcy1Δ strain failed to restore antifungal susceptibility, while susceptibility was obtained by introducing a wild-type FCY1 allele. We thus found a correlation between the fcy1 T26C mutation and both 5FC and 5FC/FLC resistances. We demonstrated that only two genetic events occurred in 11 unrelated clinical isolates of C. lusitaniae to support 5FC and 5FC/FLC resistance: either the nonsense mutation C505T in the fcy2 gene or the missense mutation T26C in the fcy1 gene.

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Sterol and Fatty Acid Composition of Candida lusitaniae Clinical Isolates

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.46.2.531-533.2002 ◽

2002 ◽

Vol 46 (2) ◽

pp. 531-533 ◽

Cited By ~ 9

Author(s):

F. Peyron ◽

A. Favel ◽

R. Calaf ◽

A. Michel-Nguyen ◽

R. Bonaly ◽

...

Keyword(s):

Fatty Acid ◽

Amphotericin B ◽

Fatty Acid Pattern ◽

Sterol Composition ◽

Clinical Isolates ◽

Cationic Dye ◽

In Vitro Susceptibility ◽

Candida Lusitaniae ◽

Fatty Acid Compositions

ABSTRACT The sterol and fatty acid compositions of four amphotericin B-resistant and of two amphotericin B-susceptible Candida lusitaniae clinical isolates were determined. A flow cytofluorometric susceptibility test (FCST) with a membrane potential-sensitive cationic dye was used as a complement to the conventional method for selecting the isolates. Compared to susceptible isolates, resistant ones showed a greatly reduced ergosterol content and changes in sterol composition, consistent with a defect in Δ8→7 isomerase. Within each group, no correlation between the sterol or fatty acid pattern or composition and both the degree of in vitro susceptibility and FCST MIC was found.

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Intrinsic in vitro susceptibility of primary clinical isolates of Aspergillus fumigatus, Aspergillus terreus, Aspergillus nidulans, Candida albicans and Candida lusitaniae against amphotericin B

Mycoses ◽

10.1111/j.1439-0507.2006.01197.x ◽

2006 ◽

Vol 49 (2) ◽

pp. 96-103 ◽

Cited By ~ 10

Author(s):

Jagpal Singh ◽

Dagmar Rimek ◽

Reinhard Kappe

Keyword(s):

Candida Albicans ◽

Aspergillus Fumigatus ◽

Aspergillus Nidulans ◽

Amphotericin B ◽

Aspergillus Terreus ◽

Clinical Isolates ◽

In Vitro Susceptibility ◽

Candida Lusitaniae

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Antifungal Susceptibilities of Clinical Isolates of Candida Species, Cryptococcus neoformans, and Aspergillus Species from Taiwan: Surveillance of Multicenter Antimicrobial Resistance in Taiwan Program Data from 2003

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.2.512-517.2005 ◽

2005 ◽

Vol 49 (2) ◽

pp. 512-517 ◽

Cited By ~ 67

Author(s):

Po-Ren Hsueh ◽

Yeu-Jun Lau ◽

Yin-Ching Chuang ◽

Jen-Hsien Wan ◽

Wen-Kuei Huang ◽

...

Keyword(s):

Antimicrobial Resistance ◽

Cryptococcus Neoformans ◽

Amphotericin B ◽

Antifungal Agents ◽

Candida Parapsilosis ◽

Clinical Isolates ◽

Study Group ◽

Fungal Isolates ◽

Candida Lusitaniae ◽

Program Data

ABSTRACT The susceptibilities of nonduplicate isolates to six antifungal agents were determined for 391 blood isolates of seven Candida species, 70 clinical isolates (from blood or cerebrospinal fluid) of Cryptococcus neoformans, and 96 clinical isolates of four Aspergillus species, which were collected in seven different hospitals in Taiwan (as part of the 2003 program of the study group Surveillance of Multicenter Antimicrobial Resistance in Taiwan). All isolates of Candida species other than C. glabrata and C. krusei were susceptible to fluconazole. Among the 59 C. glabrata isolates, 16 (27%) were not susceptible to fluconazole, and all were dose-dependently susceptible or resistant to itraconazole. For three (5.1%) C. glabrata isolates, voriconazole MICs were 2 to 4 μg/ml, and for all other Candida species isolates, voriconazole MICs were ≤0.5 μg/ml. The proportions of isolates for which amphotericin B MICs were ≥2 μg/ml were 100% (3 isolates) for C. krusei, 11% (23 of 207 isolates) for Candida albicans, 3.0% (2 of 67 isolates) for Candida tropicalis, 20% (12 of 59 isolates) for C. glabrata, and 0% for both Candida parapsilosis and Candida lusitaniae. For three (4%) Cryptococcus neoformans isolates, fluconazole MICs were ≥16 μg/ml, and two (3%) isolates were not inhibited by 1 μg of amphotericin B/ml. For four (4.2%) of the Aspergillus isolates, itraconazole MICs were 8 μg/ml. Aspergillus flavus was less susceptible to amphotericin B, with the MICs at which 50% (1 μg/ml) and 90% (2 μg/ml) nsrsid417869\delrsid7301351 of isolates were inhibited being twofold greater than those for Aspergillus fumigatus and Aspergillus niger. All Aspergillus isolates were inhibited by ≤1 μg of voriconazole/ml, including isolates with increased resistance to amphotericin B and itraconazole. This study revealed the emergence in Taiwan of decreased susceptibilities of Candida species to amphotericin B and of C. neoformans to fluconazole and amphotericin B. Voriconazole was the most potent agent against the fungal isolates tested, including fluconazole- and amphotericin B-nonsusceptible strains.

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Azasordarins: Susceptibility of Fluconazole-Susceptible and Fluconazole-Resistant Clinical Isolates ofCandida spp. to GW 471558

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.45.6.1905-1907.2001 ◽

2001 ◽

Vol 45 (6) ◽

pp. 1905-1907 ◽

Cited By ~ 5

Author(s):

Manuel Cuenca-Estrella ◽

Emilia Mellado ◽

Teresa M. Dı́az-Guerra ◽

Araceli Monzón ◽

Juan L. Rodrı́guez-Tudela

Keyword(s):

Candida Albicans ◽

Candida Glabrata ◽

Candida Parapsilosis ◽

Candida Guilliermondii ◽

Candida Krusei ◽

Clinical Isolates ◽

In Vitro Activity ◽

Fluconazole Resistant ◽

Candida Lusitaniae

ABSTRACT The in vitro activity of the azasordarin GW 471558 was compared with those of amphotericin B, flucytosine, itraconazole, and ketoconazole against 177 clinical isolates of Candidaspp. GW 471558 showed potent activity against Candida albicans, Candida glabrata, and Candida tropicalis, even against isolates with decreased susceptibility to azoles. Candida krusei, Candida parapsilosis, Candida lusitaniae, and Candida guilliermondii are resistant to GW 471558 in vitro (MICs, >128 μg/ml).

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