Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina-PR, Brazil.
Mycoses. 2011 Nov;54(6):e816-20. doi: 10.1111/j.1439-0507.2011.02035.x. Epub 2011 Jun 14.
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.
虽然溶血因子被认为是一种假定的毒力因子，有助于念珠菌属物种的致病性，但对热带念珠菌产生溶血因子的情况了解甚少。在这项研究中，我们分析了在平板测定中热带念珠菌可以显示溶血因子的培养条件，以及从不同标本获得的临床分离株在液体培养基中分泌溶血因子的情况。所有测试的分离株在绵羊血琼脂培养基上表现出内部半透明环，类似于β溶血，周围是绿色-灰色晕环。在富含人血的培养基上也观察到类似的溶血模式。此外，在正常大气或增加 CO2 下孵育对溶血没有影响。总的来说，在β溶血活性方面（P > 0.05），测试的热带念珠菌分离株之间没有观察到差异。在葡萄糖限制培养基（含 0.2%葡萄糖的 RPMI 1640）中，没有分离株在红细胞上诱导溶血。与平板测定一样，在液体培养基中分泌的溶血因子的活性在热带念珠菌分离株之间没有显著差异（P > 0.05）。然而，生长后，酵母细胞的数量在分离株之间存在差异，表明溶血因子的产生效率不同。溶血活性既不受热处理（100°C）抑制，也不受胃蛋白酶抑制剂 A 的添加抑制。所得结果扩展了我们对念珠菌属产生溶血因子的认识。
