Bujdáková Helena, Kulková Nad'a, Černáková Lucia
Comenius University, Faculty of Natural Sciences, Department of Microbiology and Virology, Bratislava, Slovakia.
Arh Hig Rada Toksikol. 2012 Dec;63(4):497-503. doi: 10.2478/10004-1254-63-2012-2236.
The biofilm of Candida albicans has been implicated as a source of bloodstream infections. Dispersal cells, as the final biofilm stage, are responsible for its spread. The aim of this study was to compare the susceptibility of biofilm and dispersal cells vs. planktonic cells (overnight liquid culture) of C. albicans to caspofungin (CAS) and fluconazole (FLU) when the drugs were added: i) at the beginning of the experiment; ii) after 1.5 h (adherence stage); iii) after 24 h (early mature biofilm). The findings were evaluated after 48 h (mature biofilm) using the XTT reduction assay. Later administration of the drug increased biofilm sessile minimal inhibitory concentration (SMIC(80)) of both FLU and CAS from 1 μg mL(-1) to over 64 μg mL(-1) and from 0.125 μg mL(-1) to over 16 μg mL(-1), respectively. Susceptibility of dispersal cells also decreased with time of administration. We also determined the expression of the Als1 and Als3 genes in 48-h sessile biofilm and dispersal cells of C. albicans SC5314 and compared it to planktonic cells. The expression was normalised to the standard Act1 gene in every condition tested. Quantitative real-time PCR revealed a strong up-regulation of the Als1 gene in the dispersal cells but not in biofilm and high expression of the Als3 gene in both biofilm and dispersal cells. High expression of both Als1 and Als3 genes supports the hypothesis that dispersal cells pose a high-risk of infection.
白色念珠菌生物膜被认为是血流感染的一个来源。作为生物膜的最后阶段，分散细胞负责其传播。本研究的目的是比较白色念珠菌生物膜、分散细胞与浮游细胞（过夜液体培养物）对卡泊芬净（CAS）和氟康唑（FLU）的敏感性，当在以下时间点添加药物时：i）实验开始时；ii）1.5小时后（黏附阶段）；iii）24小时后（早期成熟生物膜）。在48小时（成熟生物膜）后使用XTT还原试验评估结果。药物的后期给药使氟康唑和卡泊芬净的生物膜固着最小抑菌浓度（SMIC(80)）分别从1 μg/mL增加到超过64 μg/mL以及从0.125 μg/mL增加到超过16 μg/mL。分散细胞的敏感性也随着给药时间而降低。我们还测定了白色念珠菌SC5314的48小时固着生物膜和分散细胞中Als1和Als3基因的表达，并将其与浮游细胞进行比较。在每个测试条件下，表达均以标准的Act1基因进行归一化。定量实时PCR显示，分散细胞中Als1基因强烈上调，而生物膜中则不然，并且在生物膜和分散细胞中Als3基因均高表达。Als1和Als3基因的高表达支持了分散细胞构成高感染风险这一假说。
