ABSTRACT

Candida glabrata is a common non-albicans Candida species found in patients with candidiasis and it sometimes develops antifungal resistance. Human beta-defensin-3 (hBD-3) is an antimicrobial peptide of immune system active against various types of microbes including Candida spp. This study investigated antifungal activity of hBD-3 and its synergistic effect with a first-line antifungal agent on C. glabrata clinical isolates. Candida spp. were characterised in patients with candidiasis. The antifungal activities of hBD-3 and fluconazole against C. glabrata were evaluated using Broth microdilution assay. The synergistic activity of these two agents was determined by checkerboard microdilution and time-killing assays. The cytotoxicity of hBD-3 was evaluated using LDH-cytotoxicity colorimetric assay. Of 307 episodes from 254 patients diagnosed with candidiasis, C. glabrata was found in 21 clinical isolates. Antifungal susceptibility tests of C. glabrata were performed, fluconazole demonstrated an inhibitory effect at concentrations of 0.25-8 μg/ml, but one antifungal resistant strain was identified (>64 μg/ml). hBD-3 showed an inhibitory effect against all selected strains at concentrations of 50-75 μg/ml and exhibited a synergistic effect with fluconazole at the fractional inhibitory concentration index (FICI) of 0.25-0.50. A concentration of 25 μg/ml of hBD-3 alone showed no cytotoxicity but synergistic activity was seen with fluconazole. In conclusion, hBD-3 has antifungal activity against C. glabrata and synergistic effects with fluconazole at concentrations that alone, have no cytotoxicity. hBD-3 could be used as an adjunctive therapy with first-line antifungal agents for patients with C. glabrata infection particularly those infected with fluconazole-resistant strains.

摘要

光滑念珠菌是念珠菌病患者中常见的非白色念珠菌种类，有时会产生抗真菌药性。人β-防御素-3 (hBD-3) 是一种免疫系统的抗菌肽，对包括念珠菌属在内的各种类型的微生物有活性。本研究调查了 hBD-3 的抗真菌活性及其与一线抗真菌剂对C. glabrata临床分离株的协同作用。念珠菌属。以念珠菌病患者为特征。hBD-3和氟康唑对光滑念珠菌的抗真菌活性使用肉汤微量稀释法进行评估。这两种药剂的协同活性是通过棋盘式微稀释和时间杀伤试验确定的。使用LDH-细胞毒性比色法评估hBD-3的细胞毒性。在 254 名被诊断患有念珠菌病的患者的 307 次发作中，在 21 个临床分离株中发现了光滑念珠菌。C. glabrata 的抗真菌药敏试验进行时，氟康唑在 0.25-8 μg/ml 的浓度下表现出抑制作用，但鉴定出一种抗真菌菌株（>64 μg/ml）。hBD-3 在 50-75 μg/ml 的浓度下显示出对所有选定菌株的抑制作用，并在 0.25-0.50 的分数抑制浓度指数 (FICI) 下显示出与氟康唑的协同作用。浓度为 25 μg/ml 的 hBD-3 单独显示没有细胞毒性，但与氟康唑一起观察到协同活性。总之，hBD-3 具有抗光滑念珠菌的抗真菌活性，并且在单独使用时没有细胞毒性的氟康唑浓度下具有协同作用。hBD-3 可用作光滑念珠菌患者一线抗真菌药物的辅助治疗 感染，尤其是那些感染了耐氟康唑菌株的人。