Department of Microbiology and Virology, Zanjan University of Medical Sciences, Zanjan, Iran.
Department of Microbiology and Virology, Zanjan University of Medical Sciences, Zanjan, Iran.
J Glob Antimicrob Resist. 2017 Sep;10:21-28. doi: 10.1016/j.jgar.2017.03.006. Epub 2017 Jun 4.
Pseudomonas aeruginosa quorum sensing (QS) circuits regulate virulence factors and co-ordinate bacterial pathogenicity. This study aimed to investigate the inhibitory activity of subinhibitory concentrations of curcumin with azithromycin and gentamicin against P. aeruginosa QS-related genes and virulence factors.
The minimum inhibitory concentrations (MICs) and synergistic activity of curcumin with azithromycin and gentamicin against P. aeruginosa PAO1 were determined using broth microdilution and checkerboard titration methods, respectively. The activity of sub-MICs (1/4× and 1/16× MIC) of curcumin on the QS signal molecules was assessed using a reporter strain assay. The influence of sub-MICs of curcumin, azithromycin and gentamicin alone and in combination on motility and biofilm formation was also determined and was confirmed by RT-PCR to test the expression of the QS regulatory genes lasI, lasR, rhlI and rhlR.
Addition of curcumin drastically decreased the MIC of azithromycin and gentamicin. Curcumin showed synergistic effects with azithromycin and gentamicin. Treated PAO1 cultures in the presence of curcumin showed a significant reduction of signals C12-HSL and C4-HSL (P<0.05). Sub-MICs (1/4× and 1/16× MIC) of curcumin, azithromycin and gentamicin alone and in combination significantly reduced swarming and twitching motilities as well as biofilm formation. Expression of QS regulatory genes lasI, lasR, rhlI and rhlR using 1/4× MIC of curcumin, azithromycin and gentamicin alone and in combination was decreased significantly compared with untreated PAO1.
These results indicate that a combination of sub-MIC of curcumin with azithromycin and gentamicin exhibited synergism against P. aeruginosa QS systems.
铜绿假单胞菌群体感应（QS）回路调节毒力因子并协调细菌致病性。本研究旨在研究亚抑菌浓度的姜黄素与阿奇霉素和庆大霉素联合对铜绿假单胞菌 QS 相关基因和毒力因子的抑制活性。
使用肉汤微量稀释法和棋盘滴定法分别确定姜黄素对铜绿假单胞菌 PAO1 的最小抑菌浓度（MIC）和协同活性。使用报告菌株测定法评估亚 MIC（1/4×和 1/16×MIC）的姜黄素对 QS 信号分子的活性。还测定了亚 MIC 的姜黄素、阿奇霉素和庆大霉素单独和联合对运动性和生物膜形成的影响，并通过 RT-PCR 进行了验证，以测试 QS 调节基因 lasI、lasR、rhlI 和 rhlR 的表达。
添加姜黄素可显著降低阿奇霉素和庆大霉素的 MIC。姜黄素与阿奇霉素和庆大霉素具有协同作用。在姜黄素存在的情况下处理 PAO1 培养物时，C12-HSL 和 C4-HSL 的信号明显减少（P<0.05）。亚 MIC（1/4×和 1/16×MIC）的姜黄素、阿奇霉素和庆大霉素单独和联合显著降低了群集和抽动运动以及生物膜形成。与未处理的 PAO1 相比，单独使用 1/4×MIC 的姜黄素、阿奇霉素和庆大霉素以及联合使用时，QS 调节基因 lasI、lasR、rhlI 和 rhlR 的表达明显降低。
这些结果表明，亚 MIC 的姜黄素与阿奇霉素和庆大霉素联合使用对铜绿假单胞菌 QS 系统表现出协同作用。
