Navegando por Palavras-chave "Aspergillus flavus"
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- ItemEmbargoCaracterização genotípica e fenotípica de isolados clínicos e ambientais pertencentes a aspergillus seção flavi(Universidade Federal de São Paulo (UNIFESP), 2011-03-30) Goncalves, Sarah Santos [UNIFESP]; Colombo, Arnaldo Lopes [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)The species of Aspergillus section Flavi have been extensively reported as causative agents of human infectious diseases, and have shown the ability to produce aflatoxins. There is no accurate method for identification of the genus Aspergillus at species level. Because of this inconsistence, the polyphasic approach for species discrimination has been proposed. The aim of the present study was to correctly identify 74 Aspergillus isolates (28 clinical and 46 environmental) deposited in the filamentous fungi bank of the Laboratório Especial de Micologia/Brazil and of the Facultat de Medicina i Ciències de la Salut de Reus/Spain, with previous identification suggested as species belonged to the Aspergillus section Flavi. This study was based on combination of several molecular, morphological, physiological, and ecological data in a polyphasic approach, comparing the isolates to type and/or neotype strains used as reference strains. Genetic markers were selected for phylogenetic inference of the 74 isolates, including the ITS region, structural and protein-coding genes. The phenotypic characterization was performed by macro and micromorphological analyses, aflatoxin production, carbon and nitrogen assimilation, evaluation of thermotolerance and of the in vitro susceptibility profile to ten antifungals. The genomic sequencing of the ITS region confirmed that the isolates belonged to section Flavi and revealed two main clades of clinical interest. Thus, we selected genetic markers (AMDS, OMTS, and others genes) with discriminatory potential to identify the species included in each clade. Phylogenetic analyses of those genes demonstrated eight species, two undescribed. The first new species was closely related to A. flavus and A. oryzae, and the second one was closely related to A. parasiticus. In addition to ability to cause invasive infection in humans, the two new species produce aflatoxins. Among 28 clinical isolates studied, A. flavus was the most prevalent species (42.8%). In relation to environmental isolates, A. oryzae was the most frequent (63%), being also prevalent in the nosocomial environment and responsible for 65.1% (15/23) of the isolates. Moreover, antifungal susceptibility testing showed heterogeneous patterns among the species of section Flavi. Terbinafine and echinocandins were the most active antifungal agents against the Aspergillus isolates. Posaconazole was the triazole with better in vitro activity against the fungal strains studied. In conclusion, this was the first Brazilian study showing the wide heterogeneity of the species in Aspergillus section Flavi isolated from clinical and environmental sources, with different antifungal susceptibility patterns. We found two new species causing human infection, thereby demonstrating the emergence of new fungal pathogens in immunocompromised patients.
- ItemSomente MetadadadosMolecular and mycotoxigenic biodiversity of Aspergillus flavus isolated from Brazil nuts(Elsevier Science Bv, 2016) Baquiao, Arianne Costa; Lopes, Evandro Luiz [UNIFESP]; Correa, BeneditoThe objective of this study was to carry out a transcription analysis of eight genes belonging to the aflatoxin (AF) and cyclopiazonic acid (CPA) biosynthesis pathway, and to detect aflatoxin B-1 (AFB(1)) and CPA production in Aspergillus flavus strains isolated from Brazil nuts. Additionally, these genes were correlated with the different mycotoxigenic profiles of the same strains. Four previously identified A. flavus strains (ICB-01, ICB-151, ICB-161, and ICB-165) were grown on Brazil nut agar at 25 degrees C for 10 days. Mycotoxins were separated by high-performance liquid chromatography. Transcriptional analysis was performed by real-time RT-PCR using specific primers designed based on the conserved regions of two regulatory genes (aflR and aflS), three structural genes of the AFB(1) biosynthesis pathway (aflH, aflJ and aflP), and three structural genes of the CPA biosynthesis pathway (maoA, dmaT and pks-nrps). The expression of most genes in the A. flavus isolates varied according to the mycotoxin profile of each strain. The most expressed genes in the aflatoxigenic strain ICB-151 were aflJ (77.11%) and aflH (32.75%), while the CPA-producing strain ICB-161 mainly expressed dmaT (100%), maoA (63.72%), aflS (43.52%), and aflR (42.63%). The ICB-01 isolate was a producer of AFB(1) and CPA and the most expressed genes were aflS (47.79%), dmaT (42.77%), aflP (39.5%), and aflR (38.02%). ICB-198 did not produce any mycotoxin and exhibited lower expression of almost all genes analyzed. Furthermore, the ratio of aflS/aflR expression was correlated with the biosynthesis of AF and CPA in A. flavus strains producing exclusively AF or CPA or producing both AF and CPA. The ratio of aflS/aflR expression therefore seems to be related to the production of mycotoxins in Brazil nuts. Our results provide important data for the development of innovative and more cost-effective strategies to reduce and prevent AFB and CPA contamination in Brazil nuts. (C) 2016 Published by Elsevier Ltd.
- ItemSomente MetadadadosMolecular phylogeny and phenotypic variability of clinical and environmental strains of Aspergillus flavus(Elsevier B.V., 2012-11-01) Goncalves, Sarah S. [UNIFESP]; Cano, Josep F.; Stchigel, Alberto M.; Melo, Analy S. [UNIFESP]; Godoy-Martinez, Patricio C.; Correa, Benedito; Guarro, Josep; Universidade Federal de São Paulo (UNIFESP); Univ Rovira & Virgili; Univ Austral Chile; Universidade de São Paulo (USP)Aspergillus flavus is the second most common cause of aspergillosis infection in immunocompromised patients and is responsible for the production of aflatoxins. Little is known about the population structure of A. flavus, although recent molecular and phenotypic data seem to demonstrate that different genetic lineages exist within this species. the aim of this study was to carry out a morphological, physiological, and molecular analysis of a set of clinical and environmental isolates to determine whether this variability is due to species divergence or intraspecific diversity, and to assess whether the clinical isolates form a separate group. the amdS and omtA genes were more phylogenetically informative than the other tested genes and their combined analysis inferred three main clades, with no clear distinction between clinical and environmental isolates. No important morphological and physiological differences were found between the members of the different clades, with the exception of the assimilation of D-glucosamine, which differentiates the members of the clade II from the others. (C) 2012 the British Mycological Society. Published by Elsevier B.V. All rights reserved.
- ItemAcesso aberto (Open Access)Pharmacodynamics of the Novel Antifungal Agent F901318 for Acute Sinopulmonary Aspergillosis Caused by Aspergillus flavus(Oxford Univ Press Inc, 2018) Negri, Clara Ezequiel [UNIFESP]; Johnson, Adam; McEntee, Laura; Box, Helen; Whalley, Sarah; Schwartz, Julie A.; Ramos-Martin, V.; Livermore, Joanne; Kolamunnage-Dona, Ruwanthi; Colombo, Arnaldo Lopes [UNIFESP]; Hope, William W.Background. Aspergillus flavus is one of the most common agents of invasive aspergillosis and is associated with high mortality. The orotomides are a new class of antifungal agents with a novel mechanism of action. An understanding of the pharmacodynamics (PD) of the lead compound F901318 is required to plan safe and effective regimens for clinical use. Methods. The pharmacokinetics (PK) and PD of F901318 were evaluated by developing new in vitro and in vivo models of invasive fungal sinusitis. Galactomannan was used as a pharmacodynamic endpoint in all models. Mathematical PK-PD models were used to describe dose-exposure-response relationships. Results. F901318 minimum inhibitory concentrations (MICs) ranged from 0.015 to 0.06 mg/L. F901318 induced a concentration-dependent decline in galactomannan. In the in vitro model, a minimum concentration: MIC of 10 resulted in suppression of galactomannan
- ItemSomente MetadadadosRelative populations and toxin production by Aspergillus flavus and Fusarium verticillioides in artificially inoculated corn at various stages of development under field conditions(Wiley-Blackwell, 2008-01-01) Zorzete, Patricia; Castro, Rosimar S.; Pozzi, Claudia R.; Israel, Ana Lia M.; Fonseca, Hornero; Yanaguibashi, Gianni [UNIFESP]; Correa, Benedito; Universidade de São Paulo (USP); Inst Zootecnia; Universidade Federal de São Paulo (UNIFESP)The presence, development and production of mycotoxins by Aspergillus flavus and Fusarium verticillioides were studied in corn ears under field conditions after artificial contamination of corn silks. the planted area was divided into five treatments: T1, inoculated with A.flavus solution containing 1 x 10(8) spores, ears covered; T2, inoculated with F. verticillioides solution containing 1 X 10(8) spores, ears covered; T3, inoculated with E verticillioides plus A. flavus solution containing 1 x 10(8) spores of each, ears covered; T4, sprayed with sterile phosphate-buffered saline, ears covered; TS, non-sprayed silks, uncovered ears. Soil and air samples were also collected and analysed for the occurrence of fungi. Water activity, relative air humidity, rainfall and temperature were determined to assess the correlation between abiotic factors and the presence of fungi in the samples. Contamination with the inoculated fungus predominated in T1 and T2. in the other treatments, F. verticillioides was the most frequently isolated contaminant irrespective of treatment. Considering the production of mycotoxins, a positive relation between the production of fumonisins B-1 and B-2 and the frequency of F. verticillioides was statistically verified in all treatments. (C) 2007 Society of Chemical Industry.