VERA LUCIA TEIXEIRA DE FREITAS
Projetos de Pesquisa
Unidades Organizacionais
Departamento de Moléstias Infecciosas e Parasitárias, Faculdade de Medicina
LIM/48 - Laboratório de Imunologia, Hospital das Clínicas, Faculdade de Medicina
LIM/48 - Laboratório de Imunologia, Hospital das Clínicas, Faculdade de Medicina
4 resultados
Resultados de Busca
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- A Real Time PCR strategy for the detection and quantification of Candida albicans in human blood(2020) BUSSER, Felipe Delatorre; COELHO, Vivian Caso; FONSECA, Claudia de Abreu; NEGRO, Gilda Maria Barbaro Del; SHIKANAI-YASUDA, Maria Aparecida; LOPES, Marta Heloisa; MAGRI, Marcello Mihailenko Chaves; FREITAS, Vera Lucia Teixeira deCandidemia is a significant cause of bloodstream infections (BSI) in nosocomial settings. The identification of species can potentially improve the quality of care and decrease human mortality. Quantitative PCR (qPCR) was evaluated for Candida albicans detection using culture suspensions containing C. albicans, spiked human blood. the cloned qPCR target fragment (ITS2 region) and the results of these assays were compared. The assays showed a good detection limit: C. albicans DNA extracted from yeast (sensitivity 0.2 CFU/mu L), spiked human blood (sensitivity 10 CFU/mL), and cloned fragment of ITS2 region (sensitivity 20 target copies/mu L). The efficiency of ITS2 fragment-qPCR ranged from 89.67 to 97.07, and the linearity (R-2) of the standard curve ranged from 0.992 to 0.999. The results showed that this ITS2-qPCR has a great potential as a molecular prototype model for the development of a test to be applied in clinical practice, greatly reducing the time of candidemia diagnosis, which is extremely important in this clinical setting.
- Multilocus Sequence Typing of Candida tropicalis Shows the Presence of Different Clonal Clusters and Fluconazole Susceptibility Profiles in Sequential Isolates from Candidemia Patients in Sao Paulo, Brazil(2013) MAGRI, Marcello Mihailenko Chaves; GOMES-GOUVEA, Michele Soares; FREITAS, Vera Lucia Teixeira de; MOTTA, Adriana Lopes; MORETTI, Maria Luiza; SHIKANAI-YASUDA, Maria AparecidaThe profiles of 61 Candida tropicalis isolates from 43 patients (28 adults and 15 children) diagnosed with candidemia at two teaching hospitals in Sao Paulo, Brazil, were characterized by multilocus sequence typing (MLST). For the 14 patients who had bloodstream infections, 32 isolates were serially collected from their blood and/or catheters. Thirty-nine diploid sequence types (DSTs) were differentiated. According to the C. tropicalis MLST database (http://pubmlst.org/ctropicalis/), 36 DSTs and 23 genotypes identified from the 61 isolates had not previously been described. This report represents the first study to characterize sequential isolates of C. tropicalis from candidemia cases in South America. Microvariation in a single gene was found in the sequential isolates from 7 patients. The main polymorphisms occurred in the alleles of the XYR1 gene, specifically at nucleotide positions 215, 242, and 344. Macrovariation in six gene fragments was detected in the isolates from 3 patients. eBURST analysis added two new groups to this study (groups 6 and 18). Additionally, susceptibility tests indicate that 3 isolates were resistant to fluconazole. No correlation was found between the DSTs and susceptibility to fluconazole and/or selective antifungal pressure. Two patients were sequentially infected with resistant and susceptible strains. MLST is an important tool for studying the genetic diversity of multiple/sequential isolates of patients with candidemia, allowing the comparison of our data with those from other regions of the world, as well as allowing an analysis of the genetic relationship among several clones in sequential isolates from the same or different candidemia patient sites (blood or catheter).
- Performance of a Real-Time PCR Assay for the Detection of Five Candida Species in Blood Samples from ICU Patients at Risk of Candidemia(2023) FELIX, Gabriel N.; FREITAS, Vera L. T. de; SILVA JUNIOR, Afonso R. da; MAGRI, Marcello M. C.; ROSSI, Flavia; SEJAS, Odeli N. E.; ABDALA, Edson; MALBOUISSON, Luiz M. S.; GUIMARAES, Thais; BENARD, Gil; NEGRO, Gilda M. B. DelThe gold standard for diagnosing invasive candidiasis still relies on blood cultures, which are inefficient and time-consuming to analyze. We developed an in-house qPCR assay to identify the 5 major Candida species in 78 peripheral blood (PB) samples from ICU patients at risk of candidemia. Blood cultures and (1,3)-beta-D-glucan (BDG) testing were performed concurrently to evaluate the performance of the qPCR. The qPCR was positive for DNA samples from all 20 patients with proven candidemia (positive PB cultures), showing complete concordance with Candida species identification in blood cultures, except for detection of dual candidemia in 4 patients, which was missed by blood cultures. Additionally, the qPCR detected Candida species in six DNA samples from patients with positive central venous catheters blood (CB) but negative PB cultures. BDG values were similarly high in these six samples and the ones with proven candidemia, strongly suggesting the diagnosis of a true candidemia episode despite the negative PB cultures. Samples from patients neither infected nor colonized yielded negative results in both the qPCR and BDG testing. Our qPCR assay was at least as sensitive as blood cultures, but with a shorter turnaround time. Furthermore, negative results from the qPCR provided strong evidence for the absence of candidemia caused by the five major Candida species.
conferenceObject Candida tropicalis bloodstream infection in two teaching hospitals in Sao Paulo State, Brazil(2012) MAGRI, M. M. C.; DUARTE, R. D.; FREITAS, V. L. T.; COSTA, S. F.; REIS, F. A.; MORETTI, M. L.; YASUDA, M. A. ShikanaiCandidemia is considered one of the most frequent causes of bloodstream infections around the world, causing considerable morbimortality and increasing the length of hospitalization, and overall cost of medical expenses. Aims: To compare molecular methods for characterization of Candida tropicalis isolates of two teaching hospitals; to study the antifungal resistance profile Materials and methods: In this study 61 Candida tropicalis isolates (43 patients) from several unities of Hospital das Clı ́nicas da Faculdade de Medicina da USP and Hospital das Clínicas da UNICAMP have been analyzed by antifungigram and molecular typing. Antifungigram was studied through two methods: CLSI and EUCAST. For molecular characterization, RAPD (Randomic Arbitrary Polymorphic DNA) and Pulsed Field Electrophoresis (PFGE) with restriction enzymes (SfiI, SmaI, BssHII e NaeI) were analyzed. Results: BssHII presented best performance for discrimination of the isolates. PFGE was able to show differences among multiple isolates of the same patient. ‘‘Trailing’’ was observed by CLSI and EUCAST in 30 – 70% of the samples tested with azoles. Resistance to fluconazole was observed in 5% of the isolates. Four patients presented with positive blood culture during antifungal therapy: only one was resistant to fluconazole (CLSI and EUCAST). Conclusions: No correlation was found between genetic variability and resistance profile to antifungal drugs. In this study, specific clones have not been observed in each teaching hospital.