Navegando por Palavras-chave "Modelo invertebrado"

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    Aspectos microbiológicos e epidemiológicos das infecções de corrente sanguínea pelo complexo Candida parapsilosis em hospitais da América Latina
    (Universidade Federal de São Paulo (UNIFESP), 2016-05-30) Souza, Ana Carolina Remondi [UNIFESP]; Colombo, Arnaldo Lopes [UNIFESP]; http://lattes.cnpq.br/4512261018429681; http://lattes.cnpq.br/7120403222585386; Universidade Federal de São Paulo (UNIFESP)
    The importance of C. parapsilosis species complex as agents of bloodstream infections has risen in recent years, however there is little data about the potential biological, epidemiological and clinical peculiarities related to these three species. In this study we evaluated the epidemiology, antifungal susceptibility profile and virulence of C. parapsilosis (sensu stricto), Candida metapsilosis and Candida orthopsilosis isolates recovered from bloodstream infections in different Latin America hospitals. A total of 317 isolates of C. parapsilosis (sensu lato) were tested and characterized in two groups: (i) Group 1 (308 isolates from hospitals in Latin America) and (ii) Group 2 (nine isolates from a private hospital in Brasilia, Brazil). Speciation of the isolates was confirmed through molecular identification using real time PCR. The in vitro antifungal susceptibility testing was performed using the CLSI broth microdilution methodology. Isolates of C. parapsilosis (sensu stricto) with minimum inhibitory concentration values (MIC) at or above the epidemiologic cutoff (ECV) to fluconazole were analyzed for molecular mechanisms of resistance to this drug. For virulence analysis, representative isolates of each species were analyzed for biofilm formation capability and pathogenesis using C. elegans model. For Group 1, among the 308 isolates, 274 (88,9%) were identified as C. parapsilosis (sensu stricto), 26 (8,5%) as C. orthopsilosis and eight (2,6%) as C. metapsilosis. All isolates were susceptible to amphotericin B and anidulafungin. Regarding fluconazole, 24 C. parapsilosis (sensu stricto) isolates exhibit MIC at or above the ECV, four of them were considered non-susceptible. According to the analysis for molecular mechanisms of drug resistance, 20 of them revealed that at least one mechanism is expressed in these isolates. All species of the complex C. parapsilosis showed equal ability to produce biofilms. Using C. elegans as an invertebrate model host, we observed that the three species of C. parapsilosis complex feature a similar pathogenic potential inducing different immune response of the infected host. For Group 2, all isolates were identified as C. parapsilosis (sensu stricto) and exhibited fluconazole resistance phenotype. About the expression of molecular mechanisms of resistance, all isolates showed a non-synonymous mutation in ERG11 and also overexpression of ERG11 and CDR1. The Galleria mellonella infection model was used to confirm in vitro resistance. Our results showed that bloodstream infections by C. parapsilosis species complex have clinical importance in Latin America, involving three species whose pathogenic potential seems very similar. Although infrequent, in vitro and in vivo fluconazole resistance can be documented in infections by C. parapsilosis (sensu stricto).
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    Galleria mellonella como modelo invertebrado hospedeiro de infecção para estudo do complexo Candida guilliermondii: análise de virulência
    (Universidade Federal de São Paulo (UNIFESP), 2018-11-28) Luiz, Rita Angelica [UNIFESP]; Colombo, Arnaldo Lopes [UNIFESP]; Souza, Ana Carolina Remondi [UNIFESP]; http://lattes.cnpq.br/7120403222585386; http://lattes.cnpq.br/4512261018429681; http://lattes.cnpq.br/5192568581590914; Universidade Federal de São Paulo (UNIFESP)
    The genus Candida is responsible for most of fungal infections in the hospital environment. Although C. albicans remains the most prevalent species in candidemia, there is an increase in infections by non-Candida albicans species, and among them, there are some species caused by the C. guilliermondii complex. Although the pathogenic potential of C. guilliermondii has already been demonstrated, there are few studies in the literature evaluating the mechanisms of virulence involved during the development of the infection by this complex. OBJECTIVES: To evaluate putative differences in the virulence of isolates representative of the two clinical relevance species belonging to the C. guilliermondii complex (C. guilliermondii sensu stricto and C. fermentati) through analysis of biofilm formation and survival curve in the Galleria mellonella infection model. MATERIALS AND METHODS: A total of 61 isolates of the C. guilliermondii complex obtained from blood cultures of patients with documented fungus in Latin American hospitals from 2008-2016 were selected from the Bank of Microorganisms of Laboratório (LEMI), at the Federal University of São Paulo (UNIFESP). Isolates from this complex were previously identified by Molecular Sequencing method using the ITS region. The biofilm formation assays were performed on a microtiter plate and quantified by staining with crystal violet. Infection in the G. mellonella model was performed using inoculum of six representative isolates of each C. guilliermondii complex species, and the survival curve of the invertebrates was evaluated. RESULTS: Among the 61 isolates of the C. guilliermondii complex, 39 were identified and confirmed as C. guilliermondii (sensu stricto) and 22 as C. fermentati. Regarding biofilm formation by C. guilliermondii (sensu stricto) isolates, 12 (30.8%) were classified as low formers, 20 (51.3%) intermediate and seven (17.9%) as high biofilm formers. For C. fermentati, 4 isolates (16.7%) presented low biofilm formation, 12 (50%) and 8 isolates (33.3%) presented intermediate and high capacity, respectively. In a model of infection using G. mellonella, it was observed that both species were able to trigger an infectious process in the invertebrate host, and no relationship between mortality curve of the animals and the greater or lesser biofilm production by the tested isolates was documented. CONCLUSIONS: The present work demonstrated that species of C. fermentati and C. guilliermondii sensu stricto present similar characteristics of pathogenicity, at least in relation to biofilm production and death curve in invertebrate models.