Zhouying Huang, Chen Li, Ruiqi Wang, Kang Liao, Ji Zeng
Department of Laboratory Medicine, Union Hospital, Huazhong University of Science and Technology, Guangzhou, China.
Department of Clinic Laboratory, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.
Indian J Med Microbiol. 2017 Apr-Jun;35(2):252-255. doi: 10.4103/ijmm.IJMM_15_171.
The paradoxical effect of fungi, (which is a special phenomenon that certain Candida spp. might exhibit augmented growth in the presence of echinocandin at some concentration higher than the minimum inhibitory concentration) would be better illustrated through growth curves.
We investigated the paradoxical effect of caspofungin and micafungin on the growth and cell viability of 38 clinical isolates of Candida albicans using a microbial sensitivity test and growth curve methodology.
When cells were incubated in the presence of antifungal agents for 48 h, the paradoxical effect was observed in 50% and 47.4% of the isolates incubated with caspofungin and micafungin, respectively. Growth curves indicated the occurrence of the paradoxical effect varied between different echinocandins. Moreover, increased turbidity in the sensitivity test did not correlate with increased fungal cell growth. For caspofungin, the paradoxical effect appeared earlier than in the microbial sensitivity test, while for micafungin, the effect observed in the microbial sensitivity test was not a true paradoxical effect.
The growth curve methodology is more accurate for evaluating the occurrence of the paradoxical effect in comparison with the microbial sensitivity test.
真菌的矛盾效应（即某些念珠菌属在高于最低抑菌浓度的一定浓度棘白菌素存在下可能表现出生长增强的特殊现象）通过生长曲线能得到更好的阐释。
我们使用微生物敏感性试验和生长曲线方法，研究了卡泊芬净和米卡芬净对38株白色念珠菌临床分离株生长和细胞活力的矛盾效应。
当细胞在抗真菌剂存在下孵育48小时时，分别在50%和47.4%用卡泊芬净和米卡芬净孵育的分离株中观察到矛盾效应。生长曲线表明，不同棘白菌素之间矛盾效应的发生情况有所不同。此外，敏感性试验中浊度增加与真菌细胞生长增加并无关联。对于卡泊芬净，矛盾效应比微生物敏感性试验中出现得更早，而对于米卡芬净，在微生物敏感性试验中观察到的效应并非真正的矛盾效应。
与微生物敏感性试验相比，生长曲线方法在评估矛盾效应的发生方面更为准确。
