Laboratory of Biofilms and Antimicrobial Agents (LaBAM), Faculty of Medicine, Federal University of Ceara – UFC, Sobral, Brazil
Center for Bioprospecting and Applied Molecular Experimentation (NUBEM), University Center INTA – UNINTA, Sobral, Brazil
Protein Pept Lett. 2020;27(11):1124-1131. doi: 10.2174/0929866527666200416145549.
Ciprofloxacin (Cip) is the most commonly used quinolone in clinical practice; however large-scale use has favored the increase of multiresistant pathogenic microorganisms. Antimicrobial peptides (AMPs) appear to be a promising alternative in potentiating these conventional drugs.
The aim of this study was to evaluate the effect of the peptide Lys-[Trp6]hy-a1 (lys-a1) on the antimicrobial and antibiofilm activity of ciprofloxacin against clinically relevant gram-negative bacteria.
The antimicrobial effects of Cip and lys-a1 were assessed by determining the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). The synergistic action of Cip and lys-a1 was determined by checkerboard assay. The time-kill curve was constructed for the Cip/lys-a1 combination against Pseudomonas aeruginosa ATCC 9027. The antibiofilm activity of this combination was analyzed by crystal violet, colony-forming unit count and atomic force microscopy (AFM).
The data demonstrated that lys-a1 was able to inhibit planktonic growth of strains of P. aeruginosa and Klebsiella pneumoniae both at 125 μg/mL. The fractional inhibitory concentration index (FICi) showed a synergistic effect between Cip and lys-a1 against P. aeruginosa, decreasing the MICs of the individual antimicrobial agents by 4- and 8-fold, respectively. This effect was also observed for the death kinetics and antibiofilm activity. Analysis of the early biofilms (6 h) as well as isolated cells by AFM images evidenced the cell perturbation caused by Cip/lys-a1 treatment.
These data suggest that lys-a1 has biotechnological potential as a therapeutic tool for the treatment of infections caused by clinically relevant microorganisms, especially P. aeruginosa.
环丙沙星（Cip）是临床实践中最常用的喹诺酮类药物；然而，大规模使用有利于增加多耐药的致病微生物。抗菌肽（AMPs）似乎是增强这些传统药物的有前途的替代品。
本研究旨在评估肽 Lys-[Trp6]hy-a1（lys-a1）对临床相关革兰氏阴性菌的环丙沙星的抗菌和抗生物膜活性的影响。
通过测定最低抑菌浓度（MICs）和最低杀菌浓度（MBCs）来评估 Cip 和 lys-a1 的抗菌作用。通过棋盘试验确定 Cip 和 lys-a1 的协同作用。构建了 Cip/lys-a1 组合对铜绿假单胞菌 ATCC 9027 的时间杀伤曲线。通过结晶紫、菌落形成单位计数和原子力显微镜（AFM）分析该组合的抗生物膜活性。
数据表明，lys-a1 能够以 125 μg/mL 的浓度抑制铜绿假单胞菌和肺炎克雷伯菌的浮游生长。分数抑菌浓度指数（FICi）显示 Cip 和 lys-a1 对铜绿假单胞菌具有协同作用，使单个抗菌剂的 MIC 分别降低了 4 倍和 8 倍。这种作用也观察到了死亡动力学和抗生物膜活性。通过 AFM 图像对早期生物膜（6 h）和分离细胞的分析表明，Cip/lys-a1 处理会引起细胞扰动。
这些数据表明，lys-a1 具有生物技术潜力，可作为治疗临床相关微生物引起的感染的治疗工具，尤其是铜绿假单胞菌。
