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Won TH, Bok JW, Nadig N, Venkatesh N, Nickles G, Greco C, Lim FY, González JB, Turgeon BG, Keller NP, Schroeder FC. Copper starvation induces antimicrobial isocyanide integrated into two distinct biosynthetic pathways in fungi. Nat Commun 2022; 13:4828. [PMID: 35973982 PMCID: PMC9381783 DOI: 10.1038/s41467-022-32394-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 07/29/2022] [Indexed: 01/26/2023] Open
Abstract
The genomes of many filamentous fungi, such as Aspergillus spp., include diverse biosynthetic gene clusters of unknown function. We previously showed that low copper levels upregulate a gene cluster that includes crmA, encoding a putative isocyanide synthase. Here we show, using untargeted comparative metabolomics, that CrmA generates a valine-derived isocyanide that contributes to two distinct biosynthetic pathways under copper-limiting conditions. Reaction of the isocyanide with an ergot alkaloid precursor results in carbon-carbon bond formation analogous to Strecker amino-acid synthesis, producing a group of alkaloids we term fumivalines. In addition, valine isocyanide contributes to biosynthesis of a family of acylated sugar alcohols, the fumicicolins, which are related to brassicicolin A, a known isocyanide from Alternaria brassicicola. CrmA homologs are found in a wide range of pathogenic and non-pathogenic fungi, some of which produce fumicicolin and fumivaline. Extracts from A. fumigatus wild type (but not crmA-deleted strains), grown under copper starvation, inhibit growth of diverse bacteria and fungi, and synthetic valine isocyanide shows antibacterial activity. CrmA thus contributes to two biosynthetic pathways downstream of trace-metal sensing.
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Affiliation(s)
- Tae Hyung Won
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Jin Woo Bok
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA
| | - Nischala Nadig
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA
| | - Nandhitha Venkatesh
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA
| | - Grant Nickles
- Department of Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, WI, USA
| | - Claudio Greco
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA
- Department of Molecular Microbiology, John Innes Centre, Norwich, NR4 7UH, United Kingdom
| | - Fang Yun Lim
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | - Jennifer B González
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY, USA
- 104 Peckham Hall, Nazareth College, 4245 East Avenue, Rochester, NY, USA
| | - B Gillian Turgeon
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY, USA
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, USA.
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA.
| | - Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA.
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Carvalho ÂR, Genz Bazana LC, Ferrão MF, Fuentefria AM. Curve fitting and linearization of UV-Vis spectrophotometric measurements to estimate yeast in inoculum preparation. Anal Biochem 2021; 625:114216. [PMID: 33933444 DOI: 10.1016/j.ab.2021.114216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 03/24/2021] [Accepted: 04/16/2021] [Indexed: 11/29/2022]
Abstract
The counting of microorganisms is essential in the area of microbiology, especially in the preparation of inoculum. The main methods for obtaining inoculum are McFarland standard, Neubauer chamber, and plate count. However, the visual comparison is subjective while the counting in the chamber and the plating are technically time-consuming. For this reason, our article aims to correlate the absorbance of the spectrophotometer in the visible ultraviolet region (UV-Vis) with the cell counting in the Neubauer chamber. This study used suspensions of Candida spp. measured at three wavelengths (530, 600, and 700 nm) and counting in a Neubauer chamber. In the next step, curves were adjusted with different polynomials using absorbances and counts. The two best polynomial curve fittings were the Saturation Growth Rate (SGR) and Morgan-Mercer-Flodin (MMF). Therefore, the polynomials were linearized and a direct correlation between absorbance and the number of cells was made. The proposed method proved to be more accurate (5 ± 0.5 × 106) than the comparison with the McFarland turbidity (1-5 x 106) and more practical than plate counting. Predicting the number of cells by UV-Vis is an alternative that reduces the uncertainty of the cell count interval for inoculum preparation.
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Affiliation(s)
- Ânderson Ramos Carvalho
- Laboratório de Pesquisa em Micologia Aplicada, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.
| | - Luana Candice Genz Bazana
- Laboratório de Pesquisa em Micologia Aplicada, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Marco Flôres Ferrão
- Programa de Pós-Graduação em Química, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, 91501-970, Brazil
| | - Alexandre Meneghello Fuentefria
- Laboratório de Pesquisa em Micologia Aplicada, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
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Ibrahim AB, Mahmoud GA, Meurer F, Bodensteiner M. Preparation and crystallographic studies of a new mercuric salicylaldimine complex for fabrication of microscaled and nanoscaled mercuric sulfide as antimicrobial agents against human pathogenic yeasts and filamentous fungi. Appl Organomet Chem 2020. [DOI: 10.1002/aoc.6134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Ahmed B.M. Ibrahim
- Department of Chemistry, Faculty of Science Assiut University Assiut 71516 Egypt
| | | | - Florian Meurer
- Faculty of Chemistry and Pharmacy University of Regensburg Regensburg Germany
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Arendrup MC, Kahlmeter G, Guinea J, Meletiadis J. How to: perform antifungal susceptibility testing of microconidia-forming dermatophytes following the new reference EUCAST method E.Def 11.0, exemplified by Trichophyton. Clin Microbiol Infect 2020; 27:55-60. [PMID: 32916260 DOI: 10.1016/j.cmi.2020.08.042] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/26/2020] [Accepted: 08/31/2020] [Indexed: 12/17/2022]
Abstract
BACKGROUND Antifungal drug resistance in dermatophytes was first reported shortly after the turn of the millennium and has today been reported in Trichophyton and occasionally in Microsporum, but not in Epidermophyton species. Although drug resistance in dermatophytes is not routinely investigated, resistance in Trichophyton spp. is increasingly reported worldwide. The highest rates are observed in India (36% and 68% for terbinafine (MIC ≥4 mg/L) and fluconazole (MICs ≥16 mg/L), respectively), and apparently involve the spread of a unique clade related to the Trichophyton mentagrophytes/Trichophyton interdigitale complex. OBJECTIVES The European Committee on Antimicrobial Susceptibility Testing Subcommittee on Antifungal Susceptibility Testing (EUCAST-AFST) has released a new method (E.Def 11.0) for antifungal susceptibility testing against microconidia-forming dermatophytes including tentative MIC ranges for quality control strains and tentative breakpoints against Trichophyton rubrum and T. interdigitale. Here, the details of the new procedure E.Def 11.0 are described. SOURCES This technical note is based on the multicentre validation of the EUCAST dermatophyte antifungal susceptibility testing method, the mould testing method (E.Def 9.3.2) and the updated quality control tables for antifungal susceptibility testing document, v 5.0 (available on the EUCAST website). CONTENTS The method is based on the EUCAST microdilution method for moulds but significant differences include: (a) an altered test medium selective for dermatophytes; (b) an altered incubation time and temperature; and (c) a different end-point criterion (spectrophotometric determination) of fungal growth. It can easily be implemented in laboratories already performing EUCAST microdilution methods and has been validated for terbinafine, voriconazole, itraconazole and amorolfine against T. rubrum and T. interdigitale. IMPLICATIONS This standardized procedure with automated end-point reading will allow broader implementation of susceptibility testing of dermatophytes and so facilitate earlier appropriate therapy. This is important, as resistance is rapidly emerging and largely underdiagnosed.
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Affiliation(s)
- Maiken C Arendrup
- Unit of Mycology, Department of Microbiological Surveillance and Research, Statens Serum Institut, Copenhagen, Denmark; Department of Clinical Microbiology, University Hospital Rigshospitalet, Copenhagen, Denmark; Department of Clinical Medicine, University of Copenhagen, Denmark.
| | - Gunnar Kahlmeter
- The EUCAST Development Laboratory, Clinical Microbiology, Växjö, Sweden
| | - Jesus Guinea
- Clinical Microbiology and Infectious Diseases Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain; CIBER de Enfermedades Respiratorias-CIBERES (CB06/06/0058), Madrid, Spain; Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | - Joseph Meletiadis
- Clinical Microbiology Laboratory, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece; Department of Medical Microbiology and Infectious Diseases, Erasmus MC, Rotterdam, the Netherlands
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Kaur P, Balomajumder C. Bioremediation process optimization and effective reclamation of mixed carbamate-contaminated soil by newly isolated Acremonium sp. CHEMOSPHERE 2020; 249:125982. [PMID: 32078848 DOI: 10.1016/j.chemosphere.2020.125982] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 11/19/2019] [Accepted: 01/19/2020] [Indexed: 06/10/2023]
Abstract
Global pollution from excessive pesticide use has become a serious environmental and public health problem. The aim of the study was to optimize the fungal mediated simultaneous removal of carbofuran and carbaryl from soil. Carb-PV5 strain was isolated from contaminated soil following enrichment culture technique; based on 18S rRNA sequencing, strain was identified as Acremonium sp. (MK514615); Field Emission Scanning Electron Microscopic analysis reflected its morphology. Towards the development of bioaugmentation strategy for the bioremediation of carbamate-contaminated soil, the process parameters were optimized employing Central Composite Rotatable Method. The experimental studies were performed in the range of biomass (0.2-0.6 g kg-1), temperature (23-33 °C), pH (6-9) and moisture (10-30%). The degradation rate parameters, k and t1/2 were determined to as 0.475, 0.325 d-1 and 5.39, 2.1 d with the corresponding r2 of 0.9491, 0.9964 for zero and first order, respectively. The cube root growth kinetic constant k of Acremonium sp. varied from 0.0469 to 0.0512 (g1/3 L-1/3 h-1) and 0.0378 to 0.0415 (g1/3 L-1/3 h-1) for carbofuran and carbaryl, respectively. To confirm the model appropriacy and sustainability of the optimization procedure, bioremediation experiments were conducted onto real carbamate-contaminated soils. UPLC and GCMS analysis confirmed the successful removal of carbamates. The current study presents the first report on the bioaugmentation studies carried out on the mixed carbamate contaminated soil using newly isolated Acremonium sp.
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Affiliation(s)
- Parminder Kaur
- Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India.
| | - Chandrajit Balomajumder
- Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
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Optimization of production conditions for xylanase production by newly isolated strain Aspergillus niger through solid state fermentation of oil palm empty fruit bunches. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2017. [DOI: 10.1016/j.bcab.2017.07.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Endophytic Bacteria Isolated from Panax ginseng Improves Ginsenoside Accumulation in Adventitious Ginseng Root Culture. Molecules 2017; 22:molecules22060837. [PMID: 28545250 PMCID: PMC6152624 DOI: 10.3390/molecules22060837] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 05/17/2017] [Accepted: 05/17/2017] [Indexed: 01/08/2023] Open
Abstract
Ginsenoside is the most important secondary metabolite of ginseng. Natural sources of wild ginseng have been overexploited. Although root culture could reduce the length of the growth cycle of ginseng, the number of ginsenosides is fewer and their contents are lower in adventitious roots of ginseng than that in ginseng cultivated in the field. In this study, we investigated the effects of endophytic bacterial elicitors on biomass and ginsenoside production in adventitious roots cultures of Panax ginseng. Endophyte LB 5-3 as an elicitor could increase biomass and ginsenoside accumulation in ginseng adventitious root culture. After 6 days elicitation with a 10.0 mL of strain LB 5-3, the content of total ginsenoside was 2.026 mg g−1 which was four times more than that in unchallenged roots. The combination of methyl jasmonate and strain LB 5-3 had a negative effect on ginseng adventitious root growth and ginsenoside production. The genomic DNA of strain LB 5-3 was sequenced, and was found to be most closely related to Bacillus altitudinis (KX230132.1). The challenged ginseng adventitious root extracts exerted inhibitory effect against the HepG2 cells, which IC50 value was 0.94 mg mL−1.
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Anyanwu MU, Okoye RC. Antimicrobial activity of Nigerian medicinal plants. JOURNAL OF COMPLEMENTARY MEDICINE RESEARCH 2017; 6:240-259. [PMID: 28512606 PMCID: PMC5429085 DOI: 10.5455/jice.20170106073231] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Accepted: 12/19/2016] [Indexed: 11/24/2022]
Abstract
Antimicrobial resistance (AMR) is currently one of the major threats facing mankind. The emergence and rapid spread of multi- and pan-drug-resistant organisms (such as vancomycin-, methicillin-, extended-spectrum β-lactam-, carbapenem- and colistin-resistant organisms) has put the world in a dilemma. The health and economic burden associated with AMR on a global scale are dreadful. Available antimicrobials have been misused and are almost ineffective with some of these drugs associated with dangerous side effects in some individuals. Development of new, effective, and safe antimicrobials is one of the ways by which AMR burden can be reduced. The rate at which microorganisms develop AMR mechanisms outpaces the rate at which new antimicrobials are being developed. Medicinal plants are potential sources of new antimicrobial molecules. There is renewed interest in antimicrobial activities of phytochemicals. Nigeria boasts of a huge heritage of medicinal plants and there is avalanche of researches that have been undertaken to screen antimicrobial activities of these plants. Scientific compilation of these studies could provide useful information on the antimicrobial properties of the plants. This information can be useful in the development of new antimicrobial drugs. This paper reviews antimicrobial researches that have been undertaken on Nigerian medicinal plants.
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Balouiri M, Sadiki M, Ibnsouda SK. Methods for in vitro evaluating antimicrobial activity: A review. J Pharm Anal 2016; 6:71-79. [PMID: 29403965 PMCID: PMC5762448 DOI: 10.1016/j.jpha.2015.11.005] [Citation(s) in RCA: 2445] [Impact Index Per Article: 305.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Revised: 11/21/2015] [Accepted: 11/23/2015] [Indexed: 11/21/2022] Open
Abstract
In recent years, there has been a growing interest in researching and developing new antimicrobial agents from various sources to combat microbial resistance. Therefore, a greater attention has been paid to antimicrobial activity screening and evaluating methods. Several bioassays such as disk-diffusion, well diffusion and broth or agar dilution are well known and commonly used, but others such as flow cytofluorometric and bioluminescent methods are not widely used because they require specified equipment and further evaluation for reproducibility and standardization, even if they can provide rapid results of the antimicrobial agent's effects and a better understanding of their impact on the viability and cell damage inflicted to the tested microorganism. In this review article, an exhaustive list of in vitro antimicrobial susceptibility testing methods and detailed information on their advantages and limitations are reported.
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Affiliation(s)
- Mounyr Balouiri
- Laboratory of Microbial Biotechnology, Faculty of Sciences and Techniques, University Sidi Mohamed Ben Abdellah, B.P. 2202 Imouzzer Road, Fez, Morocco
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Arendrup MC, Howard S, Lass-Flörl C, Mouton JW, Meletiadis J, Cuenca-Estrella M. EUCAST testing of Isavuconazole susceptibility in Aspergillus: comparison of results for Inoculum standardization using Conidium counting versus optical density. Antimicrob Agents Chemother 2014; 58:6432-6. [PMID: 25136005 PMCID: PMC4249446 DOI: 10.1128/aac.03779-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 08/08/2014] [Indexed: 11/20/2022] Open
Abstract
The EUCAST E.DEF9.1 standard recommends standardization of the inoculum concentration by conidium counting using a hemocytometer rather than a spectrophotometer. In this study, we investigated whether the choice of these methods influenced isavuconazole MICs. A blinded collection of 30 molecularly characterized azole-resistant isolates and 10 wild-type Aspergillus fumigatus isolates was shared with four different laboratories. Additionally, each laboratory selected approximately 100 A. fumigatus isolates and 50 isolates each of A. flavus, A. nidulans, A. niger, and A. terreus (1,237 isolates in total). Three laboratories (laboratories 1 to 3) used conidium counting. One laboratory standardized the inoculum using a spectrophotometer (that is, by use of the optical density [OD]) and is referred to as the OD laboratory. Correlation coefficients, intraclass correlation coefficients, and essential agreement were calculated, and 2-log-unit differences were assessed (paired t test). The MIC range for the blinded collection was 0.25 to 16 mg/liter, and a 1-dilution-step difference between the MIC50 and MIC90 across the four laboratories was detected and a 2-dilution-step difference between the modal MICs was detected. Compared to the results for laboratories 1 and 2, a significant correlation was found for the OD laboratory MIC data (correlation coefficients, 0.85 and 0.93, respectively; intraclass correlation coefficients, 0.88 and 0.96, respectively). The number of mutant isolates whose MICs overlapped those of the wild-type isolates was the lowest for the OD laboratory (14/30 [46.7%] mutant isolates), whereas the numbers were 18/30 (60%) isolates for laboratory 1, 17/30 (56.7%) isolates for laboratory 2, and 21/30 (70%) isolates for laboratory 3. For the A. flavus, A. fumigatus, A. nidulans, A. niger, and A. terreus isolates, comparative analysis again defined the MIC distributions from the OD laboratory to be in excellent agreement with those from laboratories 1 and 2 across all five Aspergillus spp. The findings suggest that EUCAST testing using OD determination is an appropriate alternative for standardization of Aspergillus inoculum concentrations.
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Affiliation(s)
- Maiken Cavling Arendrup
- Unit of Mycology and Parasitology, Statens Serum Institut, Department of Microbiological Surveillance and Research, Copenhagen, Denmark
| | - Susan Howard
- Department of Molecular and Clinical Pharmacology, Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Cornelia Lass-Flörl
- Division of Hygiene and Medical Microbiology, Innsbruck Medical University, Innsbruck, Austria
| | - Johan W Mouton
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Joseph Meletiadis
- Clinical Microbiology Laboratory, Attikon University Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Manuel Cuenca-Estrella
- Department of Mycology, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
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Kim DM, Chung SH, Chun HS. Multiplex PCR assay for the detection of aflatoxigenic and non-aflatoxigenic fungi in meju, a Korean fermented soybean food starter. Food Microbiol 2011; 28:1402-8. [PMID: 21839392 DOI: 10.1016/j.fm.2011.06.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 06/19/2011] [Accepted: 06/24/2011] [Indexed: 10/18/2022]
Abstract
Aflatoxins are toxic secondary metabolites produced commonly by Aspergillus flavus and Aspergillus parasiticus. In this study, the possibility of using multiplex PCR was investigated to speed up and specify the detection of aflatoxigenic Aspergillus species in meju, a traditional Korean fermented soybean food starter. Two different sets of three primers were designed specifically for the omtB, ver-1, aflR, and omtA genes present in the aflatoxin biosynthesis cluster. The optimized multiplex PCR showed that only aflatoxigenic Aspergillus species gave three band patterns in both primer sets. The detection limits were determined as 125 pg/μl for genomic DNA from aflatoxigenic A. parasiticus KCCM 35078, and 10(5) spores/g of meju sample for DNA extracted directly from meju. A total of 65 Aspergillus isolates from meju were tested for the presence of aflatoxigenic fungi by the application of multiplex PCR, and were analyzed by TLC and HPLC for the aflatoxin production in the culture filtrates. Results showed a good correlation between the presence of the aflatoxin biosynthesis genes analyzed by multiplex PCR and aflatoxin production by TLC and HPLC. This suggests that this multiplex PCR method may provide an accurate and specific detection of aflatoxigenic Aspergillus species in fermented soybean foods.
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Affiliation(s)
- Dong Min Kim
- Food Safety Research Division, Korea Food Research Institute, Sungnam, Kyonggi-do, South Korea
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Diogo HC, Melhem M, Sarpieri A, Pires MC. Evaluation of the disk-diffusion method to determine the in vitro efficacy of terbinafine against subcutaneous and superficial mycoses agents. An Bras Dermatol 2010; 85:324-30. [PMID: 20676465 DOI: 10.1590/s0365-05962010000300005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 03/19/2010] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Superficial and subcutaneous mycoses have a high prevalence and, often, chronic evolution. Therefore, they need extensive treatment with topic and/or systemic antifungal agents. Azoles and alilamines (terbinafine) are first-choice drugs to treat human and animal infections. Thus, evaluation of the efficacy of these drugs is important for a successful treatment. However, there are few studies that evaluate the in vitro activity of antifungal agents. OBJECTIVE To evaluate the in vitro efficacy of terbinafine activity against filamentous fungi and yeasts that cause mycoses. METHOD The in vitro activity of terbinafine (0.125-100microg) against 10 fungi species was evaluated by the diskdiffusion and microdilution/reference methods to determine the Minimum Inhibitory Concentration (MIC). RESULTS We found a high susceptibility to terbinafine in: T. rubrum, M. gypseum, T. mentagrophytes, T. tonsurans, M. canis, C. carrionii and E. floccosum (halo > or = 40mm with 0.125microg disk). S. hyalinum and C. parapsilosis were considered susceptible, but less than the others. Fusarium spp. showed the lowest susceptibility (halo=12mm with 2microg disk; MIC 8microg/mL). CONCLUSIONS The results of this research confirm previous findings about the efficacy of terbinafine. The drug was shown to be highly effective to treat dermatophyte infections. The disk-diffusion method was easy to use and is a suitable technique for routine use in clinical laboratories.
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Lass-Flörl C. In vitro susceptibility testing in Aspergillus species: an update. Future Microbiol 2010; 5:789-99. [PMID: 20441550 DOI: 10.2217/fmb.10.34] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aspergillus species are the most common causes of invasive mold infections in immunocompromised patients. The introduction of new antifungal agents and recent reports of resistance emerging during treatment of Aspergillus infections have highlighted the need for in vitro susceptibility testing. Various testing procedures have been proposed, including macro- and micro-dilution, disk diffusion, Etest (AB Biodisk, Sweden) and other commercial tests. Although Aspergillus species are generally susceptible to various compounds, intrinsic and acquired resistance has been documented. Amphotericin B has limited activity against Aspergillus terreus and Aspergillus nidulans. Not surprisingly, continued use of azole-based drugs has the undesirable consequence of elevating the resistance of subsequent isolates from these patients. Several species in the Aspergillus fumigatus complex appear to be resistant to azoles; there is evidence of in vitro and in vivo correlation. Each in vitro susceptibility testing method has its own advantages and disadvantages. Etest is easy to perform and use on a daily basis, yet it is expensive. Disk diffusion is the most attractive alternative method to date, yet we lack sufficient data for aspergilli. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the Clinical Laboratory Standard Institute (CLSI) have produced reproducible reference testing methods. This article reviews the available methods for antifungal susceptibility testing in Aspergillus spp. as well as the scant data regarding the clinical implications of in vitro testing.
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Affiliation(s)
- Cornelia Lass-Flörl
- Department of Hygiene, Microbiology & Social Medicine, Division of Hygiene & Clinical Microbiology, Innsbruck Medical University, Fritz Pregl Str 3, 6020 Innsbruck, Austria.
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Antifungal susceptibility profile of human-pathogenic species of Lichtheimia. Antimicrob Agents Chemother 2010; 54:3058-60. [PMID: 20421405 DOI: 10.1128/aac.01270-09] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Forty-four isolates belonging to human pathogenic species of Lichtheimia were tested against nine antifungal agents by using the EUCAST methodology. No remarkable differences were found between the clinical species, although L. ramosa showed slightly higher MICs for all drugs. Amphotericin B was the most active drug. Among azole drugs, posaconazole had the best activity in vitro and voriconazole was inactive. Echinocandins showed activity for some isolates, suggesting a potential role in combination therapy.
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Lass-Flörl C, Perkhofer S, Mayr A. In vitro susceptibility testing in fungi: a global perspective on a variety of methods. Mycoses 2010; 53:1-11. [PMID: 20078786 DOI: 10.1111/j.1439-0507.2009.01813.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Candida and Aspergillus species are the most common causes of invasive fungal infections in immunocompromised patients. The introduction of new antifungal agents and recent reports of resistance emerging during treatment have highlighted the need for in vitro susceptibility testing. For some drugs, there is a supporting in vitro-in vivo correlation available from studies of clinical efficacy. Both intrinsic and emergent antifungal drug resistance are encountered. Various testing procedures have been proposed, including macrodilution and microdilution, agar diffusion, disk diffusion and Etest. Early recognition of infections caused by pathogens that are resistant to one or more antifungals is highly warranted to optimise treatment and patient outcome.
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Affiliation(s)
- Cornelia Lass-Flörl
- Department of Hygiene, Microbiology and Social Medicine, Division of Hygiene and Medical Microbiology, Innsbruck Medical University, Innsbruck, Austria.
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Alastruey-Izquierdo A, Cuesta I, Houbraken J, Cuenca-Estrella M, Monzón A, Rodriguez-Tudela JL. In vitroactivity of nine antifungal agents against clinical isolates ofAspergillus calidoustus. Med Mycol 2010; 48:97-102. [DOI: 10.3109/13693780902803040] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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17
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Rivero M, Hidalgo A, Alastruey-Izquierdo A, Cía M, Torroba L, Rodríguez-Tudela JL. Infections due toPhialemoniumspecies: case report and review. Med Mycol 2009; 47:766-74. [DOI: 10.3109/13693780902822800] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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18
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Activity of posaconazole and other antifungal agents against Mucorales strains identified by sequencing of internal transcribed spacers. Antimicrob Agents Chemother 2009; 53:1686-9. [PMID: 19171801 DOI: 10.1128/aac.01467-08] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The antifungal susceptibility profiles of 77 clinical strains of Mucorales species, identified by internal transcribed spacer sequencing, were analyzed. MICs obtained at 24 and 48 h were compared. Amphotericin B was the most active agent against all isolates, except for Cunninghamella and Apophysomyces isolates. Posaconazole also showed good activity for all species but Cunninghamella bertholletiae. Voriconazole had no activity against any of the fungi tested. Terbinafine showed good activity, except for Rhizopus oryzae, Mucor circinelloides, and Rhizomucor variabilis isolates.
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19
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Tezcan G, Ozhak-Baysan B, Alastruey-Izquierdo A, Ogunc D, Ongut G, Yildiran ST, Hazar V, Cuenca-Estrella M, Rodriguez-Tudela JL. Disseminated fusariosis caused by Fusarium verticillioides in an acute lymphoblastic leukemia patient after allogeneic hematopoietic stem cell transplantation. J Clin Microbiol 2009; 47:278-81. [PMID: 19005150 PMCID: PMC2620848 DOI: 10.1128/jcm.01670-08] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 10/02/2008] [Accepted: 11/01/2008] [Indexed: 12/18/2022] Open
Abstract
Fusarium species are saprophytic molds which cause disseminated or localized infections in humans. Disseminated Fusarium infection can cause significant morbidity and mortality in immunocompromised patients. We present a case of disseminated fusariosis caused by Fusarium verticillioides in a patient with acute lymphoblastic leukemia and successfully treated using both liposomal amphotericin B and voriconazole.
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Affiliation(s)
- Gulsum Tezcan
- Department of Medical Microbiology, Akdeniz University Medical Faculty, 07070 Antalya, Turkey
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20
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Alastruey-Izquierdo A, Castelli M, Cuesta I, Zaragoza O, Monzón A, Mellado E, Rodríguez-Tudela J. In vitro activity of antifungals against Zygomycetes. Clin Microbiol Infect 2009; 15 Suppl 5:71-6. [DOI: 10.1111/j.1469-0691.2009.02984.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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21
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EUCAST Technical Note on the method for the determination of broth dilution minimum inhibitory concentrations of antifungal agents for conidia–forming moulds. Clin Microbiol Infect 2008; 14:982-4. [DOI: 10.1111/j.1469-0691.2008.02086.x] [Citation(s) in RCA: 295] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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23
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Susceptibility testing and molecular classification of Paecilomyces spp. Antimicrob Agents Chemother 2008; 52:2926-8. [PMID: 18519716 DOI: 10.1128/aac.00538-08] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In vitro susceptibility profiles of 58 Paecilomyces clinical isolates are reported. Amphotericin B, itraconazole, and echinocandins showed poor activity against Paecilomyces lilacinus, while the new triazoles were active against it. Paecilomyces variotii exhibited a different susceptibility pattern, being susceptible to most antifungal agents apart from voriconazole and ravuconazole.
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Epidemiological cutoffs and cross-resistance to azole drugs in Aspergillus fumigatus. Antimicrob Agents Chemother 2008; 52:2468-72. [PMID: 18474574 DOI: 10.1128/aac.00156-08] [Citation(s) in RCA: 183] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antifungal susceptibility testing of molds has been standardized in Europe and in the United States. Aspergillus fumigatus strains with resistance to azole drugs have recently been detected and the underlying molecular mechanisms of resistance characterized. Three hundred and ninety-three isolates, including 32 itraconazole-resistant strains, were used to define wild-type populations, epidemiological cutoffs, and cross-resistance between azole drugs. The epidemiological cutoff for itraconazole, voriconazole, and ravuconazole for the wild-type populations of A. fumigatus was < or =1 mg/liter. For posaconazole, the epidemiological cutoff was < or =0.25 mg/liter. Up till now, isolates susceptible to itraconazole have not yet displayed resistance to other azole drugs. Cross-resistance between azole drugs depends on specific mutations in cyp51A. Thus, a substitution of glycine in position 54 of Cyp51A confers cross-resistance between itraconazole and posaconazole. A substitution of methionine at position 220 or a duplication in tandem of a 34-bp fragment in the cyp51A promoter combined with a substitution of leucine at position 98 for histidine confers cross-resistance to all azole drugs tested. The results obtained in this study will help to develop clinical breakpoints for azole drugs and A. fumigatus.
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Alcazar-Fuoli L, Rodríguez-Tudela JL, Mellado E. Antifungal drug resistance in molds: Clinical and microbiological factors. CURRENT FUNGAL INFECTION REPORTS 2008. [DOI: 10.1007/s12281-008-0006-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Rapid detection of triazole antifungal resistance in Aspergillus fumigatus. J Clin Microbiol 2008; 46:1200-6. [PMID: 18234874 DOI: 10.1128/jcm.02330-07] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Triazole resistance in Aspergillus fumigatus is an uncommon but rising phenomenon. Susceptibility testing is rarely performed and can take 48 h or longer, which is an impediment to effective therapy. Molecular diagnostic probing of well-defined resistance mechanisms, which serve as surrogate markers, provides an alternative approach to rapidly (within hours) and efficiently identify resistant strains. The mechanisms of triazole resistance in A. fumigatus are limited to amino acid substitutions in the drug target Cyp51A and include amino acid substitutions at the positions Gly 54, Gly 138, Met 220, and Leu 98, coupled with a tandem repetition in the gene promoter. We report the development of a real-time PCR assay utilizing molecular beacons to assess triazole resistance markers in A. fumigatus. When combined in a multiplex platform, the assay provides a comprehensive evaluation of drug resistance in A. fumigatus.
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Aspergillus section Fumigati: antifungal susceptibility patterns and sequence-based identification. Antimicrob Agents Chemother 2008; 52:1244-51. [PMID: 18212093 DOI: 10.1128/aac.00942-07] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
This study analyzed 28 Aspergillus strains belonging to the section Fumigati that were isolated from clinical samples in Spain. All isolates sporulated slowly and were unable to grow at 48 degrees C. Phylogenetic analysis based on sequencing of partial sequences of the beta-tubulin and rodlet A genes was used to classify the 28 strains into six different clades (Neosartorya hiratsukae, Neosartorya pseudofischeri, Aspergillus viridinutans, Aspergillus lentulus, Aspergillus fumigatiaffinis, and Aspergillus fumisynnematus). Antifungal susceptibility testing showed heterogeneous patterns and grouped the strains together by species. Most A. lentulus and A. fumigatiaffinis isolates showed high MICs of amphotericin B (geometric mean [GM] MICs, >or=4.5 microg/ml), itraconazole (GM MICs, >or=6 microg/ml), voriconazole (GM MICs, >or=3 microg/ml), and ravuconazole (GM MICs, >or=3 microg/ml); N pseudofischeri and A. viridinutans showed high MICs of itraconazole (GM MICs, >or=8 microg/ml), voriconazole (GM MICs, >or=3.33 microg/ml), and ravuconazole (GM MICs, >or=2 microg/ml); and N. hiratsukae and A. fumisynnematus were susceptible to all the antifungals tested. In conclusion, a number of different species whose morphological features resemble those of Aspergillus fumigatus could succeed in producing invasive infections in the susceptible host. In addition, some of them showed high MICs for most of the antifungals available for the treatment of patients infected with these organisms. The epidemiology and clinical relevance of these species should therefore be addressed.
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In vitro activities of 35 double combinations of antifungal agents against Scedosporium apiospermum and Scedosporium prolificans. Antimicrob Agents Chemother 2008; 52:1136-9. [PMID: 18195067 DOI: 10.1128/aac.01160-07] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Activities of 35 combinations of antifungal agents against Scedosporium spp. were analyzed by a checkerboard microdilution design and the summation of fractional concentration index. An average indifferent effect was detected apart from combinations of azole agents and echinocandins against Scedosporium apiospermum. Antagonism was absent for all antifungal combinations against both species.
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Time of incubation for antifungal susceptibility testing of Aspergillus fumigatus: can MIC values be obtained at 24 hours? Antimicrob Agents Chemother 2007; 51:4502-4. [PMID: 17938188 DOI: 10.1128/aac.00933-07] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A collection of Aspergillus fumigatus isolates was used to check if MICs can be read at 24 h. At 24 h, the geometric mean MIC of itraconazole for resistant isolates was determined to be 5.11 mg/liter, but the MIC was read as 16 mg/liter at 48 h. At 24 h, MICs for 51.5% of resistant strains were determined to be <or =2 mg/liter. MICs must be obtained at 48 h.
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Comparative in vitro pharmacodynamics of caspofungin, micafungin, and anidulafungin against germinated and nongerminated Aspergillus conidia. Antimicrob Agents Chemother 2007; 52:321-8. [PMID: 17938191 DOI: 10.1128/aac.00699-07] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The concentration-dependent effects of echinocandins on the metabolic activity of Aspergillus spp. were comparatively studied by using nongerminated and germinated conidia. The susceptibilities of 11 Aspergillus fumigatus, 8 A. terreus and 8 A. flavus isolates to caspofungin, micafungin, and anidulafungin were studied by a CLSI (formerly NCCLS) M38-A broth microdilution-based method. After 48 h of incubation the minimum effective concentration (MEC) was defined microscopically. Metabolic activity was assessed by the 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide assay and modeled by using the sigmoid (E max) or "bell-shaped" model. The median MEC values of caspofungin (0.5 to 1 microg/ml), micafungin (0.06 to 0.12 microg/ml), and anidulafungin (0.03 microg/ml) against nongerminated conidia increased by 0 to 1, 1 to 2, and 2 to 3 twofold dilutions, respectively (depending on the species), over those against germinated conidia. A similar shift to the right was demonstrated for the corresponding curves of metabolic activity. There was a significant correlation between the degrees of maximal metabolic inhibition caused by different echinocandins at both the species level (greater inhibition for A. flavus) and the strain level (r = 0.84 to 0.93; P < 0.0001). Paradoxical increases in metabolism in the presence of higher concentrations of caspofungin, micafungin, and anidulafungin were detected in 6, 2, and 5 of the A. fumigatus isolates, respectively; 5, 1, and 2 of the A. terreus isolates, respectively; and 1, 0, and 0 of the A. flavus isolates, respectively. Based on the model, 50% of the maximal paradoxical increase was detected with 4.2, 11.1, and 10.8 microg/ml of caspofungin, micafungin, and anidulafungin, respectively. All echinocandins therefore exerted comparable levels of maximal metabolic inhibition against Aspergillus spp. at concentrations that were differentially increased for germinated versus nongerminated conidia. The paradoxical increase in metabolism occurred more frequently and at lower concentrations with caspofungin than with micafungin and anidulafungin.
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Cuenca-Estrella M, Arendrup MC, Chryssanthou E, Dannaoui E, Lass-Florl C, Sandven P, Velegraki A, Rodriguez-Tudela JL. Multicentre determination of quality control strains and quality control ranges for antifungal susceptibility testing of yeasts and filamentous fungi using the methods of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST). Clin Microbiol Infect 2007; 13:1018-22. [PMID: 17697001 DOI: 10.1111/j.1469-0691.2007.01790.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A multicentre study involving seven laboratories was performed using techniques recommended by the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST) to evaluate and propose quality control ranges and strains for susceptibility testing of fermentative yeasts and filamentous fungi. Participating laboratories tested the susceptibilities of a panel of 12 encoded isolates to amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and posaconazole. In total, 15 lots of assay medium were tested, with one lot being common to all laboratories, and 18 144 MIC values were determined. Intra- and inter-laboratory agreements and intra-class correlation coefficients (ICCs) of the results for each drug/strain/lot combination were calculated. An average value of 85% agreement was selected for validation purposes. The average percentage of intra-laboratory agreement was 90-95%, with ICC values of 0.90-0.95 (p <0.01). Inter-laboratory reproducibility was also high, with 92% agreement and an ICC of 0.97 (p <0.01). The reproducibility was somewhat better with the common lot of assay medium (96% agreement) than with the different lots (91% agreement), but this difference was not significant. Two isolates that showed trailing growth had agreement percentages below the 85% limit selected for validation purposes and were therefore excluded from the panel of quality control strains. The recommended EUCAST methodologies were found to be highly reproducible and reliable for susceptibility testing of yeasts and filamentous fungi. Ten isolates are proposed for use as quality control strains with these EUCAST procedures.
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Affiliation(s)
- M Cuenca-Estrella
- National Centre for Microbiology, Instituto de Salud Carlos III, Madrid, Spain.
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32
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Meletiadis J, Antachopoulos C, Stergiopoulou T, Pournaras S, Roilides E, Walsh TJ. Differential fungicidal activities of amphotericin B and voriconazole against Aspergillus species determined by microbroth methodology. Antimicrob Agents Chemother 2007; 51:3329-37. [PMID: 17576838 PMCID: PMC2043246 DOI: 10.1128/aac.00345-07] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antifungal agents may differ in their fungicidal activities against Aspergillus spp. In order to compare the fungicidal activities of voriconazole and amphotericin B against 40 isolates of Aspergillus fumigatus, A. flavus, and A. terreus, we developed a new microbroth colorimetric method for assessing fungicidal activities and determining minimal fungicidal concentrations (MFCs). This methodology follows the antifungal susceptibility testing reference method M-38A for MIC determination. After drug removal and addition of fresh medium, growth of viable conidia adhering to the bottoms of the microtitration wells was assessed by a colorimetric assay of metabolic activity after 24 h of incubation. The new method was faster (six times), reproducible (92 to 97%), and in agreement with culture-based MFCs (91 to 100%). Differential fungicidal activities of voriconazole and amphotericin B were found among the three Aspergillus species, with A. fumigatus and A. flavus having the lowest (1 and 2 mg/liter, respectively) and A. terreus the highest (>16 mg/liter) median amphotericin B MFCs; A. flavus had a lower median voriconazole MFC (4 mg/liter) than the other species (>8 mg/liter; P < 0.05). Amphotericin B was fungicidal (MFC/MIC </= 4) against all A. fumigatus and A. flavus isolates but no A. terreus isolates, whereas voriconazole was fungicidal against 82% of A. flavus isolates and fungistatic (MFC/MIC > 4) against 94% of A. fumigatus and 84% of A. terreus isolates. The new methodology revealed a concentration-dependent sigmoid pattern of fungicidal effects, indicating that fungicidal activity is not an all-or-nothing phenomenon and that some degree of fungicidal action can be found even for agents considered fungistatic based on the MFC/MIC ratio.
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Affiliation(s)
- Joseph Meletiadis
- Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD 20892, USA
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Gadea I, Cuenca-Estrella M, Martín E, Pemán J, Pontón J, Rodríguez-Tudela JL. Procedimientos de diagnóstico microbiológico de las micosis y estudios de sensibilidad a los antifúngicos. Enferm Infecc Microbiol Clin 2007; 25:336-40. [PMID: 17504688 DOI: 10.1157/13102270] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fungal infections are a diagnostic and therapeutic problem of increasing concern due to the frequency and severity of disseminated infection in immunocompromised patients. Culture-based methods are characteristically slow and have poor sensitivity; hence, other methods, based on the detection of fungus-specific genetic, antigenic and metabolic components are being developed to enable early diagnosis and specific treatment. Moreover, reproducible antifungal susceptibility methods that can be adapted for use in clinical laboratories have been standardized to allow in vitro detection of resistance, which correlates with a less favorable clinical outcome. In this paper we review the main microbiological procedures available for the diagnosis of fungal infections and for antifungal susceptibility testing.
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Affiliation(s)
- Ignacio Gadea
- Departamento de Microbiología Médica, Fundación Jiménez Díaz, UTE, Madrid, España.
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Mellado E, Garcia-Effron G, Alcázar-Fuoli L, Melchers WJG, Verweij PE, Cuenca-Estrella M, Rodríguez-Tudela JL. A new Aspergillus fumigatus resistance mechanism conferring in vitro cross-resistance to azole antifungals involves a combination of cyp51A alterations. Antimicrob Agents Chemother 2007; 51:1897-904. [PMID: 17371828 PMCID: PMC1891382 DOI: 10.1128/aac.01092-06] [Citation(s) in RCA: 366] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fourteen Aspergillus fumigatus clinical isolates that exhibited a pattern of reduced susceptibility to triazole drugs were analyzed. The sequences of the cyp51A gene from all isolates showed the presence of a point mutation at t364a, which led to the substitution of leucine 98 for histidine (L98H), together with the presence of two copies of a 34-bp sequence in tandem in the promoter of the cyp51A gene. Quantitative expression analysis (real-time PCR) showed up to an eightfold increase in the level of expression of the cyp51A gene compared to that by the susceptible strain. Three PCR fragments of one azole-resistant strain (strain CM2627) that included the promoter with the tandem repeat and part of cyp51A with the t364a mutation or PCR fragments with only one of the modifications were used to replace the cyp51A gene of an azole drug-susceptible A. fumigatus wild-type strain (strain CM237). Only transformants which had incorporated the tandem repeat in the promoter of the cyp51A gene and the L98H amino acid substitution exhibited similarly reduced patterns of susceptibility to all triazole agents and similarly increased levels of cyp51A expression, confirming that the combination of both alterations was responsible for the azole-resistant phenotype.
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Affiliation(s)
- E Mellado
- Servicio de Micologia, Centro Nacional de Microbiologia, Instituto de Salud Carlos III, Carretera Majadahonda-Pozuelo Km2, 28220 Madrid, Spain.
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35
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Alastruey-Izquierdo A, Cuenca-Estrella M, Monzón A, Rodriguez-Tudela JL. Prevalence and susceptibility testing of new species of pseudallescheria and scedosporium in a collection of clinical mold isolates. Antimicrob Agents Chemother 2006; 51:748-51. [PMID: 17101671 PMCID: PMC1797781 DOI: 10.1128/aac.01177-06] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The prevalence of new species of Pseudallescheria and Scedosporium in a collection of 46 clinical isolates was analyzed. Strain identification was done by morphological and molecular methods. Four Scedosporium aurantiacum isolates were detected among the panel of clinical strains. The susceptibility profile of S. aurantiacum was similar to that of Scedosporium apiospermum.
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Affiliation(s)
- Ana Alastruey-Izquierdo
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra. Majadahonda-Pozuelo Km 2, 28220 Majadahonda, Madrid, Spain
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36
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Chryssanthou E, Cuenca-Estrella M. Comparison of the EUCAST-AFST broth dilution method with the CLSI reference broth dilution method (M38-A) for susceptibility testing of posaconazole and voriconazole against Aspergillus spp. Clin Microbiol Infect 2006; 12:901-4. [PMID: 16882296 DOI: 10.1111/j.1469-0691.2006.01419.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The susceptibilities of 40 clinical isolates of Aspergillus spp. (Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, Aspergillus terreus) were determined for posaconazole and voriconazole by the CLSI M38-A and EUCAST-AFST broth dilution methods. Where a discrepancy was observed between the methods, the EUCAST method tended to give higher MIC values. Overall, the level of agreement was 92.5% and the intra-class correlation coefficient was > 0.90.
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Affiliation(s)
- E Chryssanthou
- Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden.
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Gutierrez F, Masia M, Ramos JM, Elia M, Rodriguez-Tudela JL, Cuenca-Estrella M. Lack of efficacy of voriconazole therapy in 2 patients with pulmonary fungus balls. Clin Infect Dis 2006; 40:1706-7. [PMID: 15889381 DOI: 10.1086/430176] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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38
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Cuenca-Estrella M, Gomez-Lopez A, Buitrago MJ, Mellado E, Garcia-Effron G, Rodriguez-Tudela JL. In vitro activities of 10 combinations of antifungal agents against the multiresistant pathogen Scopulariopsis brevicaulis. Antimicrob Agents Chemother 2006; 50:2248-50. [PMID: 16723597 PMCID: PMC1479145 DOI: 10.1128/aac.00162-06] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The activities of 10 combinations of antifungal agents against 25 clinical isolates of Scopulariopsis brevicaulis were tested by the checkerboard technique. An average indifferent effect was detected for all combinations. Synergy was observed for some isolates and combinations, particularly with posaconazole-terbinafine (68% of strains), amphotericin B-caspofungin (60%), and posaconazole-caspofungin (48%).
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Affiliation(s)
- Manuel Cuenca-Estrella
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda (Madrid), Spain.
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Gomez-Lopez A, Martin-Gomez MT, Martin-Davila P, Lopez-Onrubia P, Gavalda J, Fortun J, Pahissa A, Rodriguez-Tudela JL, Cuenca-Estrella M. Detection of fungal DNA by real-time polymerase chain reaction: evaluation of 2 methodologies in experimental pulmonary aspergillosis. Diagn Microbiol Infect Dis 2006; 56:387-93. [PMID: 16876374 DOI: 10.1016/j.diagmicrobio.2006.06.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Revised: 06/13/2006] [Accepted: 06/13/2006] [Indexed: 11/24/2022]
Abstract
The capabilities of 2 quantitative polymerase chain reaction (PCR) assays for detecting pulmonary aspergillosis were analyzed. Both methodologies were real-time (RT) based and were compared with quantitative cultures and galactomannan (GM) antigen detection in a rabbit model of invasive aspergillosis. A total of 106 samples including blood, serum, lung, and brain from 3 controls and 9 infected New Zealand rabbits were analyzed. The RT-PCR methodologies were an Aspergillus fumigatus-specific assay using fluorescent resonance energy transfer technology targeting a highly conserved region of the fungal 18S rRNA gene and a panfungal assay to amplify the internal transcribed spacer regions 1 and 2 from fungal rRNA gene complex, employing SYBRGreen fluorescent dye as a detector. The specificity for both PCR base assays, culture, and GM determination was 100%. The sensitivity of the specific PCR assay was 88.9% in lung samples, 66.6% in serum, 55.5% in blood, and 33.3 in brain specimens. The panfungal assay had a sensitivity of 33.3% in lung and serum samples, being brain and blood specimens invariably negative. Otherwise, 100% of the lungs resulted positive for culture, and all serum samples showed a GM index above 1.0 after 2 days of infection. The specific RT-PCR assay is a reliable technique to detect A. fumigatus DNA in vivo comparable to cultures and GM determination. The panfungal RT-PCR assay exhibited low sensitivity to diagnose invasive aspergillosis in rabbits advising against its clinical introduction.
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Affiliation(s)
- Alicia Gomez-Lopez
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain
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40
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Alcazar-Fuoli L, Mellado E, Garcia-Effron G, Buitrago MJ, Lopez JF, Grimalt JO, Cuenca-Estrella JM, Rodriguez-Tudela JL. Aspergillus fumigatus C-5 sterol desaturases Erg3A and Erg3B: role in sterol biosynthesis and antifungal drug susceptibility. Antimicrob Agents Chemother 2006; 50:453-60. [PMID: 16436696 PMCID: PMC1366924 DOI: 10.1128/aac.50.2.453-460.2006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two erg3 genes encoding C-5 sterol desaturase enzymes (Erg3A and Erg3B) in Aspergillus fumigatus were characterized with respect to their nucleotide sequences and null mutant phenotypes. Targeted disruption of the erg3A and erg3B genes and a double gene knockout, erg3A- erg3B-, showed that they are not essential for A. fumigatus viability. Mutant phenotypes clearly showed that Erg3B is a C-5 sterol desaturase, but no apparent role for Erg3A in A. fumigatus ergosterol biosynthesis was found. Susceptibility to amphotericin B, itraconazole, fluconazole, voriconazole, and ketoconazole was not altered in isolates in which erg3A and erg3B were knocked out alone and in combination.
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Affiliation(s)
- Laura Alcazar-Fuoli
- Servicio de Micologia, Centro Nacional de Microbiologia, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
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41
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Cuenca-Estrella M, Gomez-Lopez A, Mellado E, Garcia-Effron G, Monzon A, Rodriguez-Tudela JL. In vitro activity of ravuconazole against 923 clinical isolates of nondermatophyte filamentous fungi. Antimicrob Agents Chemother 2006; 49:5136-8. [PMID: 16304186 PMCID: PMC1315962 DOI: 10.1128/aac.49.12.5136-5138.2005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The in vitro activities of ravuconazole against 575 clinical strains of Aspergillus spp. and 348 nondermatophyte non-Aspergillus spp. were analyzed. Ravuconazole was active against Aspergillus spp., other hyaline filamentous fungi, black molds, and some Mucorales. Species such as Scedosporium prolificans, Fusarium spp., and Scopulariopsis spp. were resistant to the triazole.
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Affiliation(s)
- Manuel Cuenca-Estrella
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra Majadahonda-Pozuelo Km 2, 28220 Majadahonda (Madrid), Spain.
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42
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Cuenca-Estrella M, Gomez-Lopez A, Mellado E, Buitrago MJ, Monzon A, Rodriguez-Tudela JL. Head-to-head comparison of the activities of currently available antifungal agents against 3,378 Spanish clinical isolates of yeasts and filamentous fungi. Antimicrob Agents Chemother 2006; 50:917-21. [PMID: 16495251 PMCID: PMC1426453 DOI: 10.1128/aac.50.3.917-921.2006] [Citation(s) in RCA: 221] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 12/10/2005] [Accepted: 01/03/2006] [Indexed: 11/20/2022] Open
Abstract
We have compared the activities of posaconazole and other currently available antifungal agents against a collection of 3,378 clinical isolates of yeasts and filamentous fungi. A total of 1,997 clinical isolates of Candida spp., 359 of other yeast species, 697 strains of Aspergillus spp., and 325 nondermatophyte non-Aspergillus spp. were included. The average geometric means of the MICs of agents that were tested against Candida spp. were 0.23 microg/ml for amphotericin B, 0.29 microg/ml for flucytosine, 0.97 microg/ml for fluconazole, 0.07 microg/ml for itraconazole, 0.04 microg/ml for voriconazole, 0.15 microg/ml for caspofungin, and 0.03 microg/ml for posaconazole. Voriconazole and posaconazole were active in vitro against the majority of isolates, with resistance to fluconazole and itraconazole, and against Cryptococcus neoformans and other Basidiomycota yeasts. Posaconazole was the most active of antifungal agents tested against Aspergillus spp., with an average geometric mean of 0.10 microg/ml. It was active against Paecilomyces spp., Penicillium spp., Scedosporium apiospermum, and some black fungi, such as Alternaria spp. Multiresistant filamentous fungi, such as Scedosporium prolificans, Scopulariopsis brevicaulis, and Fusarium solani, were also resistant to voriconazole, caspofungin, and posaconazole. Amphotericin B and posaconazole were found to be active against most of the Mucorales strains tested. Posaconazole and currently available antifungal agents exhibit a potent activity in vitro against the majority of pathogenic fungal species.
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Affiliation(s)
- Manuel Cuenca-Estrella
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra Majadahonda-Pozuelo Km 2, 28220 Majadahonda (Madrid), Spain.
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43
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Lass-Flörl C, Cuenca-Estrella M, Denning DW, Rodriguez-Tudela JL. Antifungal susceptibility testing in Aspergillus spp. according to EUCAST methodology. Med Mycol 2006; 44:S319-S325. [PMID: 30408924 DOI: 10.1080/13693780600779401] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
The availability of new antifungal agents has multiplied the demand for in vitro antifungal susceptibility testing for Aspergillus spp. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) has charged its Antifungal Susceptibility Testing Subcommittee (AFST-EUCAST) with the preparation of new guidelines for in vitro susceptibility testing of antifungals against Aspergillus spp (EUCAST-AST-ASPERGILLUS). This committee has modified the reference method for broth dilution antifungal susceptibility testing of filamentous fungi (M38-A) as follows: (i) RPMI 1640 supplemented with 2% glucose (RPMI 2%G) as assay medium, (ii) inoculum preparation by conidium counting in a haemocytometer and (iii) an inoculum size of 2×105-5×105 CFU/ml. The incubation time is about 48 h at 35°C and MIC is read visually. The MIC value is a no-growth visual endpoint. The standard method described herein is intended to provide a valid and economic method for testing the susceptibility to antifungal agents of Aspergillus spp., to identify resistance, and to facilitate an acceptable degree of conformity, e.g. agreement within specified ranges and between laboratories in measuring the susceptibility.
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Affiliation(s)
- C Lass-Flörl
- Department of Hygiene and Clinical Microbiology, University of Innsbruck, Austria
| | - M Cuenca-Estrella
- Servicio de Micologia, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Spain
| | - D W Denning
- School of Medicine and Faculty of Life Sciences, University of Manchester, UK
| | - J L Rodriguez-Tudela
- Servicio de Micologia, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Spain
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44
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Gutiérrez F, Masiá M, Ramos J, Elía M, Mellado E, Cuenca-Estrella M. Pulmonary mycetoma caused by an atypical isolate of Paecilomyces species in an immunocompetent individual: case report and literature review of Paecilomyces lung infections. Eur J Clin Microbiol Infect Dis 2005; 24:607-11. [PMID: 16187056 DOI: 10.1007/s10096-005-0013-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The first case of pulmonary fungus ball caused by Paecilomyces species is reported. The diagnosis was established by isolation of the fungus in culture from specimens obtained by percutaneous transthoracic needle aspiration in an immunocompetent individual. The isolate was atypical, as it failed to produce fruiting structures on routine mycological media. Identification was achieved by sequencing polymorphisms of the internal transcriber spacer regions of the ribosomal DNA. The antifungal susceptibility profile was also determined. This report underscores the increasing importance of Paecilomyces species in human infections. Paecilomyces should be included among the etiological agents of pulmonary mycetoma.
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Affiliation(s)
- F Gutiérrez
- Unidad de Enfermedades Infecciosas, Hospital General Universitario de Elche, Camí de la Almazara S/N, 03203, Elche, Alicante, Spain.
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45
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Mellado E, Garcia-Effron G, Buitrago MJ, Alcazar-Fuoli L, Cuenca-Estrella M, Rodriguez-Tudela JL. Targeted gene disruption of the 14-alpha sterol demethylase (cyp51A) in Aspergillus fumigatus and its role in azole drug susceptibility. Antimicrob Agents Chemother 2005; 49:2536-8. [PMID: 15917566 PMCID: PMC1140498 DOI: 10.1128/aac.49.6.2536-2538.2005] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The role of Aspergillus fumigatus 14alpha-sterol demethylase (Cyp51A) in azole drug susceptibility was assessed. Targeted disruption of cyp51A in azole-susceptible and -resistant strains decreased MICs from 2- to 40-fold. The cyp51A mutants were morphologically indistinguishable from the wild-type strain, retaining the ability to cause pulmonary disease in neutropenic mice.
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Affiliation(s)
- E Mellado
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Carretera Majadahonda-Pozuelo Km 2, 28220 Madrid, Spain.
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46
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Garcia-Effron G, Mellado E, Gomez-Lopez A, Alcazar-Fuoli L, Cuenca-Estrella M, Rodriguez-Tudela JL. Differences in interactions between azole drugs related to modifications in the 14-alpha sterol demethylase gene (cyp51A) of Aspergillus fumigatus. Antimicrob Agents Chemother 2005; 49:2119-21. [PMID: 15855543 PMCID: PMC1087680 DOI: 10.1128/aac.49.5.2119-2121.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The combined activity of different azole drugs was investigated. Thirty-one Aspergillus fumigatus strains were tested, including two cyp51A(-) and one cyp51B(-) gene-knockout strain and azole-susceptible and -resistant strains with different resistance mechanisms. The combination of itraconazole and voriconazole was synergistic for all strains except for those with gene knockouts.
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Affiliation(s)
- G Garcia-Effron
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Carretera Majadahonda-Pozuelo Km 2, 28220 Madrid, Spain
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47
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Cuenca-Estrella M, Gomez-Lopez A, Garcia-Effron G, Alcazar-Fuoli L, Mellado E, Buitrago MJ, Rodriguez-Tudela JL. Combined activity in vitro of caspofungin, amphotericin B, and azole agents against itraconazole-resistant clinical isolates of Aspergillus fumigatus. Antimicrob Agents Chemother 2005; 49:1232-5. [PMID: 15728937 PMCID: PMC549263 DOI: 10.1128/aac.49.3.1232-1235.2005] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Interactions in vitro between amphotericin B, itraconazole, voriconazole, and caspofungin against itraconazole-resistant Aspergillus fumigatus clinical strains were determined. Differential results were obtained depending on the criteria (MIC or minimal effective concentration) used. Caspofungin and voriconazole exhibited the most potent interactions, with synergy against at least 50% of isolates, and the average fractional concentration index was 0.38. Antagonism was not found for any combination.
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Affiliation(s)
- Manuel Cuenca-Estrella
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra Majadahonda-Pozuelo Km 2. 28220 Majadahonda (Madrid), Spain.
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48
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Gomez-Lopez A, Aberkane A, Petrikkou E, Mellado E, Rodriguez-Tudela JL, Cuenca-Estrella M. Analysis of the influence of Tween concentration, inoculum size, assay medium, and reading time on susceptibility testing of Aspergillus spp. J Clin Microbiol 2005; 43:1251-5. [PMID: 15750092 PMCID: PMC1081276 DOI: 10.1128/jcm.43.3.1251-1255.2005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The influence of several test variables on susceptibility testing of Aspergillus spp. was assessed. A collection of 28 clinical isolates was tested against amphotericin B, itraconazole, voriconazole, and terbinafine. Inoculum size (10(4) CFU/ml versus 10(5) CFU/ml) and glucose supplementation (0.2% versus 2%) did not have significant effects on antifungal susceptibility testing results and higher inoculum size and glucose concentration did not falsely elevate MICs. In addition, antifungal susceptibility testing procedure with an inoculum size of 10(5) CFU/ml distinctly differentiated amphotericin B or itraconazole-resistant Aspergillus strains in vivo from the susceptible ones. Time of incubation significantly affected the final values of MICs, showing major increases (two to six twofold dilutions, P < 0.01 by analysis of variance) between MIC readings at 24 and 48 h, but no differences were observed between antifungal susceptibility testing results obtained at 48 h and at 72 h. Significantly higher MICs were uniformly associated with higher concentrations of Tween (P < 0.01), used as a dispersing agent in the preparation of inoculum suspensions. The geometric mean MICs showed increases of between 1.5- and 10-fold when the Tween concentration varied from 0.1% (the geometric means for amphotericin B, itraconazole, voriconazole, and terbinafine were 1.29, 0.69, 1.06, and 0.64 mug/ml, respectively) to 5% (the geometric means for amphotericin B, itraconazole, voriconazole, and terbinafine were 1.97, 5.79, 1.60, and 4.66 mug/ml, respectively). The inhibitory effect of Tween was clearly increased with inoculum sizes of 10(5) CFU/ml and was particularly dramatic for itraconazole, terbinafine, and Aspergillus terreus. The inoculum effect was not observed when the Tween concentration was below 0.5% (P > 0.01).
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Affiliation(s)
- Alicia Gomez-Lopez
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra Majadahonda-Pozuelo, Km 2. 28220 Majadahonda, Madrid, Spain
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49
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Mellado E, Garcia-Effron G, Alcazar-Fuoli L, Cuenca-Estrella M, Rodriguez-Tudela JL. Substitutions at methionine 220 in the 14alpha-sterol demethylase (Cyp51A) of Aspergillus fumigatus are responsible for resistance in vitro to azole antifungal drugs. Antimicrob Agents Chemother 2004; 48:2747-50. [PMID: 15215142 PMCID: PMC434164 DOI: 10.1128/aac.48.7.2747-2750.2004] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Five clinical isolates of Aspergillus fumigatus that exhibited similar patterns of reduced susceptibility to itraconazole and other triazole drugs were analyzed. Sequence analysis of genes (cyp51A and cyp51B) encoding the 14alpha-sterol demethylases revealed that all five strains harbored mutations in cyp51A resulting in the replacement of methionine at residue 220 by valine, lysine, or threonine. When the mutated cyp51A genes were introduced into an A. fumigatus wild-type strain, the transformants exhibited reduced susceptibility to all triazole agents, confirming that the mutations were responsible for the resistance phenotype.
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Affiliation(s)
- E Mellado
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Carretera Majadahonda-Pozuelo Km2, 28220 Madrid, Spain.
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