- Epidemiology, clinical characteristics, and risk factors for : Medicine
- Hyphally regulated cell wall protein 1
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Culture media containing, respectively, agar-base DNA, egg yolk, and bovine albumin were used to determine DNase, phospholipase and proteinase activities, respectively.. It is concluded that all species had hemolytic activity. DNase activity was detected in all species except in C. La actividad DNasa fue detectada en todas las especies, excepto en Candida glabrata ; la actividad proteinasa fue detectada en C.
Recent increases in the incidence of fungal infections worldwide are a matter of great concern in public health. Among yeasts, Candida species remain the main cause of hospital infections, particularly in adult or pediatric intensive care units. Commensal Candida species may become pathogenic for humans if microbiota balance is disturbed. Pathogenicity will depend on factors such as host predisposition immunodepression , parasitic load and fungal virulence that facilitate tissue invasion and evasion of host defense mechanisms.
The pathogenicity of fungi has been investigated in an attempt to identify the differences in clinical presentation and severity of the infection. Among the properties of Candida species that may explain pathogenicity, different virulence factors are present, which include adhesion to substrates, formation of the germ tube, phenotypic and genotypic variability, toxin production and extracellular enzymes. These constitute important factors in the launching and maintenance of infections. Proteinases and phospholipases are among the hydrolytic enzymes produced.
Characterization of virulence factors contributes to the understanding of Candida infections, including the differences between different species. The aim of this study was to investigate the in vitro hemolytic activity, and DNase, phospholipase and proteinases activities in five species of Candida : Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata and Candida krusei.
Fifty Candida spp. Results were described and interpreted according to the characteristics of each test. Hemolytic activity was evidenced by the translucent halo with defined borders around colonies, and expressed by an index, hemolytic index Hi , calculated by dividing the colony diameter by the diameter of colony plus the hemolysis zone.
DNase activity was expressed as positive or negative by the detection of a clearing halo without defined borders around the colonies.
The activities of phospholipase and proteinase were identified by an opaque zone precipitation of a calcium complex and a clear halo around the yeast colonies, respectively, and were expressed by using the Pz value phospholipase zone for phospholipase and Prz proteinase zone for proteinase. Both Pz and Prz values were calculated by dividing the colony diameter by the colony diameter plus the precipitation or clearing, respectively, according to Price et al. The Mann—Whitney test was used to calculate statistic differences between enzymatic activities in isolates of C.
Percentage of Candida spp. The moderate hemolytic index was shown by all isolates of C. Statistical differences among species were not significant.. Frequency of Candida spp. Statistically significant differences were found between C. Phospholipase activity was present in all C. No significant differences were observed between the other species when compared in groups of two..
Infective processes are dependent on host defense mechanisms, general and local conditions and upon virulence factors characterizing the causative microorganisms. Virulence factors are widely investigated in an attempt to explain differences in pathogenicity of several fungal isolates including Candida spp. Candida isolates included in this study showed hemolytic activity with the exception of only two strains: one C.
Rorig et al. However, other authors observed in vitro hemolytic activity in isolates of C. Some of the discrepancies in the results may be due to difficulties in the quantification of hemolytic activity conducted in different test conditions, definitions and interpretations of results.
Epidemiology, clinical characteristics, and risk factors for : Medicine
Thus, the use of suggested models to characterize activities, although empirical, will permit comparison of results from different laboratories. The model proposed by Price et al. Results concerning DNase activity in Candida species were not found in the literature. Some strains of all the species, except C. This lack of information may be due again to experimental problems of the in vitro detection of the activity.
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The method requires prolonged incubation periods, and halos surrounding colonies do not have well-defined borders, suggesting the use of qualitative interpretations as positive or negative. DNase in fungi was reported by Cazin et al. The implication of extracellular DNase as a virulence factor for fungi has not yet been defined.
Hyphally regulated cell wall protein 1
Hypotheses are that DNase contributes to the evasion of the immune system, preventing the death of the yeast that can be caused by neutrophils. However recent studies have shown the role of extracellular DNase produced by C. However, future studies should be conducted in order to verify the importance of DNase for Candida spp. Phospholipase activity was detected in all C. Among the other species, only one isolate of C.
Proteinase activity was present in C. It is concluded that all the species tested had hemolytic activity; DNase activity was detected in all the species except in C.
Proteinase was detected in C. It is suggested that DNase activity observed in clinical isolates of Candida spp. The authors declare no conflict of interest.. Riceto and Ralciane P. ISSN: Enzymatic and hemolytic activity in different Candida species. Descargar PDF.
Autor para correspondencia. Table 1. Background Candida species, in conditions of microbiota imbalance or decreased immune defenses, may be one of the main human fungal pathogens. Virulence factors constitute the mechanisms used by the fungus to avoid host defenses. Aims This study aimed to investigate the in vitro production of virulence factors, such as hemolytic activity, and deoxyribonuclease DNase , proteinase, and phospholipase activities in Candida spp.
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Methods Fifty clinical isolates were analyzed for virulence factors: Candida albicans 15 , Candida tropicalis 15 , Candida parapsilosis 10 , Candida glabrata 5 , and Candida krusei 5. Culture media containing, respectively, agar-base DNA, egg yolk, and bovine albumin were used to determine DNase, phospholipase and proteinase activities, respectively. Conclusions It is concluded that all species had hemolytic activity. Palabras clave:. Texto completo.
Materials and methods Fifty Candida spp. Back-Brito, V. El Achkar, A. Garbim, A. Jorge, A. Rev Inst Adolfo Lutz, 70 , pp. Barbedo, D.
Canzi, T. Kozel, D. Lupan, W. Extracellular deoxyribonuclease production by yeasts.