Medical Microbiology and Molecular Biology Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, Uttar Pradesh, 202 002, India.
Eur J Med Res. 2020 Jun 3;25(1):19. doi: 10.1186/s40001-020-00418-1.
NDM-1 is a novel broad-spectrum metallo-β-lactamase with the capability to grant resistance to almost all β-lactam antibiotics. Its widespread dissemination made treatment options a major challenge to combat, causing threat to public health worldwide. Due to antibiotic resistance problems, development of effective therapeutics for infections caused by NDM-1 producing strains is urgently required. Since combination therapies are proved to be effective in many cases, this study was initiated to put forward novel effective antibiotics combinations for fighting infections caused by NDM-1 producing strains.
Streptomycin and amikacin combination and streptomycin and ciprofloxacin combination were tested by checkerboard assay. NDM-1 protein/enzyme was then expressed and purified to carry out enzyme kinetics study, CD and fluorescence spectroscopic studies.
Streptomycin and amikacin combination and streptomycin and ciprofloxacin combination showed synergistic effect towards NDM-1 producing bacterial strains as shown by FICI results. NDM-1 producing bacterial cells were expressed and purified to obtain protein as the source of enzyme. When NDM-1 enzyme was treated with streptomycin along with amikacin, the efficiency of enzyme was decreased by 49.37% and when the enzyme was treated with streptomycin along with ciprofloxacin, the efficiency of enzyme was decreased by 29.66% as revealed by enzyme kinetic studies. Due to binding of streptomycin and amikacin in combination and streptomycin and ciprofloxacin in combination, conformational changes in the secondary structure of NDM-1 enzyme were observed by CD spectroscopic studies. Antibiotics streptomycin and ciprofloxacin bind with NDM-1 through exothermic processes, whereas amikacin binds through an endothermic process. All three antibiotics bind spontaneously with an association constant of the order of 10 M as revealed by fluorescence spectroscopic studies.
The therapeutic combination of streptomycin with amikacin and ciprofloxacin plays an important role in inhibiting NDM-1 producing bacterial strains. Therefore, these combinations can be used as effective future therapeutic candidates against NDM-1 producing bacterial cells.
NDM-1 是一种新型广谱金属β-内酰胺酶，能够赋予几乎所有β-内酰胺抗生素的耐药性。其广泛传播使得治疗选择成为一个主要挑战，对全球公共健康构成威胁。由于抗生素耐药问题，迫切需要开发针对产 NDM-1 菌株感染的有效治疗方法。由于联合治疗在许多情况下被证明是有效的，因此本研究旨在提出针对产 NDM-1 菌株感染的新型有效抗生素联合方案。
采用棋盘微量稀释法检测链霉素和阿米卡星联合以及链霉素和环丙沙星联合的效果。然后表达和纯化 NDM-1 蛋白/酶，进行酶动力学研究、圆二色性（CD）和荧光光谱研究。
FICI 结果表明，链霉素和阿米卡星联合以及链霉素和环丙沙星联合对产 NDM-1 细菌菌株表现出协同作用。表达和纯化产 NDM-1 的细菌细胞，获得作为酶源的蛋白质。当 NDM-1 酶与阿米卡星一起用链霉素处理时，酶的效率降低了 49.37%，而当酶与环丙沙星一起用链霉素处理时，酶的效率降低了 29.66%，这是通过酶动力学研究揭示的。由于链霉素和阿米卡星联合以及链霉素和环丙沙星联合的结合，通过 CD 光谱研究观察到 NDM-1 酶的二级结构构象发生变化。抗生素链霉素和环丙沙星通过放热过程与 NDM-1 结合，而阿米卡星通过吸热过程结合。荧光光谱研究表明，所有三种抗生素都以 10 M 左右的级联常数自发结合。
链霉素与阿米卡星和环丙沙星的治疗联合在抑制产 NDM-1 细菌菌株方面发挥了重要作用。因此，这些联合方案可以作为针对产 NDM-1 细菌细胞的有效未来治疗候选药物。
