IBB-Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057, Braga, Portugal.
Mycopathologia. 2010 Mar;169(3):175-82. doi: 10.1007/s11046-009-9246-0. Epub 2009 Oct 23.
Candida tropicalis has been reported to be one of the Candida species which is most likely to cause bloodstream and urinary tract infections in hospitalized patients. Accordingly, the aim of this study was to characterize the virulence of C. tropicalis by assessing antifungal susceptibility and comparing the expression of several virulence factors. This study was conducted with seven isolates of C. tropicalis from urine and blood cultures and from central venous catheter. C. tropicalis ATCC 750 was used as reference strain. Yeasts adhered (2 h) to epithelial cells and silicone and 24 h biofilm biomass were determined by crystal violet staining. Pseudohyphae formation ability was determined after growth in fetal bovine serum. Enzymes production (hemolysins, proteases, phospholipases) was assessed by halo formation on agar plates. Susceptibility to antifungal agents was determined by E-test. Regarding adhesion, it can be highlighted that C. tropicalis strains adhered significantly more to epithelium than to silicone. Furthermore, all C. tropicalis strains were able to form biofilms and to express total hemolytic activity. However, protease was only produced by two isolates from urine and by the isolates from catheter and blood. Moreover, only one C. tropicalis (from catheter) was phospholipase positive. All isolates were susceptible to voriconazole, fluconazole and amphotericin B. Four strains were susceptible-dose dependent to itraconazole and one clinical isolate was found to be resistant.
热带假丝酵母菌已被报道为最有可能引起住院患者血流感染和尿路感染的假丝酵母菌之一。因此，本研究的目的是通过评估抗真菌药敏性和比较几种毒力因子的表达来表征热带假丝酵母菌的毒力。本研究使用了来自尿液和血液培养物以及中心静脉导管的 7 株热带假丝酵母菌分离株，以及 C. tropicalis ATCC 750 作为参考菌株。酵母在 2 小时内附着（附着）到上皮细胞和硅树脂上，并通过结晶紫染色测定 24 小时生物膜生物量。在胎牛血清中生长后，确定假菌丝形成能力。通过琼脂平板上的晕圈形成评估酶（溶血素、蛋白酶、磷脂酶）的产生。通过 E 试验测定抗真菌药物的敏感性。关于粘附，可以强调的是，C. tropicalis 菌株明显比硅树脂更能粘附在上皮细胞上。此外，所有 C. tropicalis 菌株都能够形成生物膜并表达总溶血活性。然而，只有两种来自尿液的分离株和来自导管和血液的分离株产生蛋白酶。此外，只有一株 C. tropicalis（来自导管）为磷脂酶阳性。所有分离株均对伏立康唑、氟康唑和两性霉素 B 敏感。四种菌株对伊曲康唑的敏感性为剂量依赖性，一种临床分离株被发现耐药。
