Multidrug resistance in Aspergillus nidulans involves novel ATP-binding cassette transporters

Sorbo, G. Del; Andrade, Alan Carvalho; Nistelrooy, J.G.M. van; Kan, Jan A.L. van; Balzi, Elisabetta; Waard, M.A. de

doi:10.1007/s004380050434

Cited by 128 publications

(86 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Although they have been studied in greater depth for some phytopathogenic fungi, the information about human-pathogenic fungi is very meager. In general, two classes of resistance mechanisms have been described up to now: altered affinity of CYP51 due to target site mutation (8,9) and decreased accumulation of drugs due to enhanced energy-dependent drug efflux (7,25,33). Characterization of genes encoding CYP51 will contribute to better understanding of azole resistance mechanisms at the molecular level.…”

mentioning

confidence: 99%

Identification of Two Different 14-α Sterol Demethylase-Related Genes ( cyp51A and cyp51B ) in Aspergillus fumigatus and Other Aspergillus species

et al. 2001

View full text Add to dashboard Cite

Two cyp51-related genes (cyp51A and cyp51B) encoding 14-␣ sterol demethylase-like enzymes were identified in the opportunistic human pathogen Aspergillus fumigatus. PCR amplification using degenerate oligonucleotides based on conserved areas of cytochrome P450 demethylases of other filamentous fungi and yeasts allowed the cloning and sequencing of two different homologue genes in A. fumigatus. Southern analysis confirmed that both genes hybridized to distinct genomic loci and that both are represented as single copies in the genome. Comparison of the deduced Cyp51A and Cyp51B proteins with the CYP51 proteins from Penicillium italicum, Aspergillus nidulans, Erysiphe graminis, Uncinula necator, Botrytis cinerea, Ustilago maydis, Cryptococcus neoformans, Candida albicans, Saccharomyces cerevisiae, Candida tropicalis, and Candida glabrata showed that the percentages of identity of the amino acid sequences (range, 40 to 70%) were high enough to consider Cyp51A and Cyp51B to be members of the fungal CYP51 family. Fragments from both genes were also cloned from other Aspergillus spp. (A. flavus, A. nidulans, and A. terreus). Phylogenetic analysis showed that, at least in the most pathogenic species of Aspergillus, there are two fungal CYP51 proteins. This is the first report of the existence of two homologue genes coding for 14-␣ sterol demethylase in the fungal kingdom. This finding could provide insights into the azole resistance mechanisms operating in fungi. The primers used here may be useful molecular tools for facilitating the cloning of novel 14-␣ sterol demethylase genes in other filamentous fungi.

show abstract

mentioning

confidence: 99%

Identification of Two Different 14-α Sterol Demethylase-Related Genes ( cyp51A and cyp51B ) in Aspergillus fumigatus and Other Aspergillus species

et al. 2001

View full text Add to dashboard Cite

show abstract

“…Although mutations at 10 sites within the β -tubulin gene can confer benzimidazole resistance (Davidse & Ishii, 1995), only a few have been found in field populations of fungi, probably due to reduced fitness and /or pathogenicity linked with certain mutations. For DMI resistance, an increased efflux mechanism operated by ATP-binding cassette transporters has been reported for Aspergillus nidulans (Del Sorbo et al , 1997) and Penicillium digitatum (Nakaune et al , 1998). For P. digitatum , DMI resistance can also be triggered by a transcriptional enhancer of the sterol 14 α -demethylase target gene (CYP51) (Hamamoto et al , 2000).…”

Section: Accepted 3 August 2001mentioning

confidence: 99%

Following the dynamics of strobilurin resistance in Blumeria graminis f.sp. tritici using quantitative allele‐specific real‐time PCR measurements with the fluorescent dye SYBR Green I

et al. 2002

View full text Add to dashboard Cite

Strobilurin-resistant isolates of Blumeria ( Erysiphe ) graminis f.sp. tritici , the cause of wheat powdery mildew, were more than 10-fold less sensitive to azoxystrobin than sensitive isolates. In all resistant isolates, a mutation resulting in the replacement of a glycine by an alanine residue at codon 143 (G143A) in the mitochondrial cytochrome b gene was found. Allele-specific primers were designed to detect this point mutation in infected wheat leaves. Using quantitative fluorescent allele-specific real-time polymerase chain reaction (PCR) measurements, strobilurin-resistant A143 alleles could be detected amongst strobilurin-sensitive G143 alleles at a frequency of at least 1 in 10 000, depending on the amount of target and nontarget DNA. Most isolates tested were dominant homoplasmic for either the A143 or G143 allele, although mixed populations of alleles could be detected in some isolates. In some of these isolates, strobilurin resistance was not always stable when they were maintained for many generations in the absence of selection. The allele-specific real-time PCR assay was also used to follow the dynamics of A143 alleles in field populations of B . graminis f.sp. tritici before and after application of fungicides. As expected, the A143 allele frequency only increased under selection pressure from a strobilurin fungicide. After three sprays of azoxystrobin, a pronounced selection for the strobilurin-resistant allele, with an increase in average frequency from 2·2 to 58%, was measured. The use of quantitative real-time PCR diagnostics for early detection of fungicide resistance genes at low frequency, coupled with risk evaluation, will be invaluable for further resistance risk assessment and validation of antiresistance strategies.

show abstract

“…Although CBS takes great care to preserve its isolates (17), the effect of cryopreservation or freezing-drying on phenotypic resistance is unknown. Although the mechanism of azole resistance in A. fumigatus has not been fully elucidated, reduced intracellular concentrations of itraconazole have been found in resistant isolates, and these concentrations may be mediated by efflux pumps (4,5,14). If resistance were lost during storage, the Isolates are cultured from respiratory specimens either before specific antifungal treatment is initiated or at autopsy, after primary therapy with amphotericin B has failed.…”

mentioning

confidence: 99%

Nationwide Survey of In Vitro Activities of Itraconazole and Voriconazole against Clinical Aspergillus fumigatus Isolates Cultured between 1945 and 1998

et al. 2002

View full text Add to dashboard Cite

The isolates in a collection of 170 Aspergillus fumigatus isolates recovered from 114 patients and 21 different medical centers in The Netherlands over a period of 53 years were tested for the presence of resistance to itraconazole and voriconazole according to the guidelines of NCCLS document M38-P and by the E-test. Three isolates were highly resistant to itraconazole, and voriconazole MICs were low for all isolates.Over the past few decades the incidence of invasive fungal infections has increased, especially those caused by Aspergillus species (11, 16). The treatment of choice for infected patients remains amphotericin B, although alternative drugs with activities against Aspergillus species are becoming available for clinical use, including the antifungal azoles itraconazole and voriconazole. Itraconazole is highly active against Aspergillus species but has been used almost exclusively as follow-up therapy in patients with invasive aspergillosis. However, with the availability of a new intravenous formulation of itraconazole and an oral solution, first-line therapy may become an option (1). Voriconazole is active against a wide range of filamentous molds including Aspergillus species. The drug can be administered both intravenously and orally and was found to be superior to amphotericin B as first-line therapy for the treatment of invasive aspergillosis ( Although testing of the susceptibilities of Aspergillus fumigatus isolates to amphotericin B in vitro is problematic, resistance to azoles can be detected (3,5,6). The in vitro resistance of A. fumigatus to itraconazole was confirmed by use of animal experimental models (3, 5). However, the prevalence of resistance to itraconazole and voriconazole among A. fumigatus isolates is unknown. In the present study we investigated the prevalence of resistance among A. fumigatus isolates that had been cultured from patients admitted to hospitals throughout The Netherlands.(This work was presented in part at the 38th Interscience Conference on Antimicrobial Agents and Chemotherapy, San Diego, Calif., 24 to 27 September 1998.) Medical microbiology laboratories in The Netherlands were asked to send A. fumigatus isolates that had been cultured from clinical samples at their hospitals. In addition, the database of the collection of the Centraalbureau voor Schimmelcultures (CBS) was searched for A. fumigatus isolates that had been cultured from clinical specimens from Dutch patients. The isolates were subcultured onto Sabouraud glucose agar plates supplemented with 0.5% chloramphenicol; the plates were incubated at 29°C for 7 days, and the identifications were confirmed. Candida parapsilosis ATCC 22019 and Candida krusei ATCC 6258 were used as quality controls. In addition, an itraconazole-susceptible A. fumigatus isolate (isolate AF71; MIC, 0.25 g/ml) and an itraconazole-resistant A. fumigatus isolate (isolate AF91; MIC, Ͼ64 g/ml) were included in each test (5).Reference-grade lots of itraconazole (Janssen-Cilag, Tilburg, The Netherlands) and voriconazole (Pfizer Centra...

show abstract

Multidrug resistance in Aspergillus nidulans involves novel ATP-binding cassette transporters

Cited by 128 publications

References 49 publications

Identification of Two Different 14-α Sterol Demethylase-Related Genes ( cyp51A and cyp51B ) in Aspergillus fumigatus and Other Aspergillus species

Identification of Two Different 14-α Sterol Demethylase-Related Genes ( cyp51A and cyp51B ) in Aspergillus fumigatus and Other Aspergillus species

Following the dynamics of strobilurin resistance in Blumeria graminis f.sp. tritici using quantitative allele‐specific real‐time PCR measurements with the fluorescent dye SYBR Green I

Nationwide Survey of In Vitro Activities of Itraconazole and Voriconazole against Clinical Aspergillus fumigatus Isolates Cultured between 1945 and 1998

Contact Info

Product

Resources

About