Maiolo Elena Maryka, Furustrand Tafin Ulrika, Borens Olivier, Trampuz Andrej
Septic Surgical Unit, Department of Surgery and Anesthesiology, Lausanne University Hospital, Lausanne, Switzerland.
Antimicrob Agents Chemother. 2014 May;58(5):2709-17. doi: 10.1128/AAC.00057-14. Epub 2014 Feb 24.
We investigated the activities of fluconazole, caspofungin, anidulafungin, and amphotericin B against Candida species in planktonic form and biofilms using a highly sensitive assay measuring growth-related heat production (microcalorimetry). C. albicans, C. glabrata, C. krusei, and C. parapsilosis were tested, and MICs were determined by the broth microdilution method. The antifungal activities were determined by isothermal microcalorimetry at 37°C in RPMI 1640. For planktonic Candida, heat flow was measured in the presence of antifungal dilutions for 24 h. Candida biofilm was formed on porous glass beads for 24 h and exposed to serial dilutions of antifungals for 24 h, and heat flow was measured for 48 h. The minimum heat inhibitory concentration (MHIC) was defined as the lowest antifungal concentration reducing the heat flow peak by ≥50% (≥90% for amphotericin B) at 24 h for planktonic Candida and at 48 h for Candida biofilms (measured also at 24 h). Fluconazole (planktonic MHICs, 0.25 to >512 μg/ml) and amphotericin B (planktonic MHICs, 0.25 to 1 μg/ml) showed higher MHICs than anidulafungin (planktonic MHICs, 0.015 to 0.5 μg/ml) and caspofungin (planktonic MHICs, 0.125 to 0.5 μg/ml). Against Candida species in biofilms, fluconazole's activity was reduced by >1,000-fold compared to its activity against the planktonic counterparts, whereas echinocandins and amphotericin B mainly preserved their activities. Fluconazole induced growth of planktonic C. krusei at sub-MICs. At high concentrations of caspofungin (>4 μg/ml), paradoxical growth of planktonic C. albicans and C. glabrata was observed. Microcalorimetry enabled real-time evaluation of antifungal activities against planktonic and biofilm Candida organisms. It can be used in the future to evaluate new antifungals and antifungal combinations and to study resistant strains.
我们使用一种测量与生长相关的产热的高灵敏度检测方法（微量量热法），研究了氟康唑、卡泊芬净、阿尼芬净和两性霉素B对浮游形式和生物膜中的念珠菌属的活性。对白色念珠菌、光滑念珠菌、克柔念珠菌和近平滑念珠菌进行了测试，并通过肉汤微量稀释法测定了最低抑菌浓度（MIC）。在37°C的RPMI 1640中，通过等温微量量热法测定抗真菌活性。对于浮游念珠菌，在存在抗真菌稀释液的情况下测量24小时的热流。念珠菌生物膜在多孔玻璃珠上形成24小时，然后暴露于抗真菌药物的系列稀释液中24小时，并测量48小时的热流。最低热抑制浓度（MHIC）定义为在24小时时使浮游念珠菌的热流峰值降低≥50%（两性霉素B为≥90%）以及在48小时时（也在24小时测量）使念珠菌生物膜的热流峰值降低≥50%的最低抗真菌浓度。氟康唑（浮游MHIC，0.25至>512μg/ml）和两性霉素B（浮游MHIC，0.25至1μg/ml）的MHIC高于阿尼芬净（浮游MHIC，0.015至0.5μg/ml）和卡泊芬净（浮游MHIC，0.125至0.5μg/ml）。与对浮游念珠菌的活性相比，氟康唑对生物膜中念珠菌属的活性降低了1000倍以上，而棘白菌素和两性霉素B主要保留了它们的活性。氟康唑在亚MIC浓度下诱导浮游克柔念珠菌生长。在高浓度卡泊芬净（>4μg/ml）时，观察到浮游白色念珠菌和光滑念珠菌的反常生长。微量量热法能够实时评估针对浮游和生物膜念珠菌生物体的抗真菌活性。未来可用于评估新的抗真菌药物和抗真菌联合用药，并研究耐药菌株。
