ABSTRACT
Although haemolytic factor is known to be a putative virulence factor contributing to pathogenicity in Candida species, its production by Candida tropicalis is poorly understood. In this study, we analysed the culture conditions under which C. tropicalis can display haemolytic factor on plate assay and the secretion of haemolytic factor in liquid medium by clinical isolates obtained from different specimens. All the tested isolates exhibited an internal translucent ring, resembling beta-haemolysis, surrounding by a peripheral greenish-grey halo on sheep blood agar medium. Similar haemolytic pattern was observed on human blood enriched medium. Furthermore, incubation either under normal atmosphere or under increased CO(2) had no effect on haemolysis. Overall, no differences were observed on beta-haemolytic activities (P > 0.05) among tested isolates of C. tropicalis. In glucose-limited medium (RPMI 1640 with 0.2% glucose), none of the isolates induced haemolysis on red blood cells. Similarly to found on plate assays, there were no significant differences (P > 0.05) in the activity of secreted haemolytic factor in liquid medium among C. tropicalis isolates. However, after growth, the number of yeast cells varied among isolates revealing different efficiencies of haemolytic factor production. Haemolytic activity was neither inhibited by heat treatment (100 °C) nor by the addition of pepstatin A. The obtained results extend our knowledge about haemolytic factor production by Candida species.
Subject(s)
Candida tropicalis/metabolism , Candida tropicalis/pathogenicity , Candidiasis/microbiology , Hemolysin Proteins/metabolism , Agar , Animals , Candida tropicalis/isolation & purification , Carbon Dioxide/metabolism , Culture Media/chemistry , Erythrocytes/drug effects , Hot Temperature , Humans , Mycology/methods , SheepABSTRACT
The aim of this study was to determine in vitro haemolytic and protease activities of Candida parapsilosis and Candida tropicalis isolates, obtained from anatomically distinct sites. Analysis of haemolytic activity of C. parapsilosis and C. tropicalis isolates obtained from the same anatomic site revealed that C. tropicalis isolates from blood had statistically higher activity (P < 0.05) than C. parapsilosis. On comparison of haemolytic activities of Candida isolates obtained from different anatomic sites, C. parapsilosis isolates from tracheal secretion were found to have higher activity than blood isolates. Protease activity was detected in the majority of the isolates analysed. Analysis of proteinase activity of C. parapsilosis and C. tropicalis isolates obtained from the same anatomic site revealed that C. parapsilosis isolates from tracheal secretion had statistically higher activity than C. tropicalis isolates. On comparison of proteinase activities of Candida isolates obtained from different anatomic sites, C. parapsilosis isolates from tracheal secretion were found to have higher activity than blood and superficial lesions isolates. Furthermore, C. tropicalis isolates from superficial lesions had higher activity than tracheal secretion isolates. Our results show the potential of C. parapsilosis and C. tropicalis isolates, obtained from distinct anatomic sites, to produce haemolytic factor and proteinases. Anatomic sites of isolation seem to be correlated with these activities, particularly for C. parapsilosis isolates.
Subject(s)
Candida/enzymology , Candida/isolation & purification , Hemolysin Proteins/metabolism , Peptide Hydrolases/metabolism , Virulence Factors/metabolism , Blood/microbiology , Humans , Nails/microbiology , Skin/microbiology , Sputum/microbiologyABSTRACT
A meningite por Cryptococcus neoformans e uma das patologias mais graves que acometem pacientes imunodeprimidos, em especial, os portadores da Sindrome da Imunodeficiencia Adquirida (SIDA). Com o objetivo de verificar a incidencia de Cryptococcus neoformans em nosso meio, os autores investigaram 209 Liquidos Cefalorraquidianos (LCR), provenientes de pacientes do Hospital Universitario Regional do Norte do Parana (HURNP), durante o periodo de 01/01/90 a 15/08/91. Para a investigaçao do C.Neoformans no LCR, foram realizadas a pesquisa direta a fresco com tinta da china e cultura em meio Sabouraud Agar. Dos 209 LCR investigados, 8 (3,82%) apresentaram-se positivos para C. neoformans, sendo que destes 6 (75%) eram portadores de SIDA e 1 (l2,5%) era paciente pediatrico. Os resultados mostraram que ameningite por Cryptococcus neoformas pode, esporadicamente, acometer crianças, embora a literatura cite que esta patologia incida, primordialmente, em adultos e pacientes imunodeprimidos.
