Metronidazole

Metronidazole is a nitroimidazole antibiotic medication used particularly for anaerobic bacteria and protozoa.Target: Antibacterial; AntiparasiticMetronidazole is a nitroimidazole antibiotic medication used particularly for anaerobic bacteria and protozoa. Metronidazole is an antibiotic, amebicide, and antiprotozoal.[1] It is the drug of choice for first episodes of mild-to-moderate Clostridium difficile infection [2]. Metronidazole, taken up by diffusion, is selectively absorbed by anaerobic bacteria and sensitive protozoa. Once taken up by anaerobes, it is non-enzymatically reduced by reacting with reduced ferredoxin, which is generated by pyruvate oxido-reductase. Many of the reduced nitroso intermediates will form sulfinamides and thioether linkages with cysteine-bearing enzymes, thereby deactivating these critical enzymes. As many as 150 separate enzymes are affected.In addition or alternatively, the metronidazole metabolites are taken up into bacterial DNA, and form unstable molecules. This function only occurs when metronidazole is partially reduced, and because this reduction usually happens only in anaerobic cells, it has relatively little effect upon human cells or aerobic bacteria.[3]
甲硝唑是一种硝基咪唑类抗生素药物，特别用于厌氧菌和原虫感染。甲硝唑是一种抗生素，阿米巴杀虫药和抗原虫药[1]。它是轻度至中度难治性难辨谔菌感染首选药物[2]。甲硝唑通过扩散被细菌和敏感原虫选择性吸收。一旦被厌氧菌吸收，它将与还原型三硫化铁蛋白发生非酶反应被非酶还原，生成的许多还原型亚硝基中间体将形成磺酰胺和半乙硫醚与半胱氨酸酶结合，从而使这些关键酶失活。最多可影响150种不同的酶。此外或替代的是，甲硝唑代谢物被细菌DNA吸收，形成不稳定分子。只有当甲硝唑部分还原时才会发生这种功能，因为这种还原通常仅发生在厌氧细胞中，所以对人体细胞或好氧细菌的影响相对较小[3]。

References:
[1]. In Schaechter, M.; Engleberg, N. C.; DiRita, V. J. et al. Schaechter's Mechanisms of Microbial Disease. Hagerstown, MD: Lippincott Williams & Wilkins. p. 28.
[2]. http://www.drugs.com/monograph/metronidazole.html
[3]. Cohen, S.H., et al., Clinical practice guidelines for Clostridium difficile infection in adults: 2010 update by the society for healthcare epidemiology of America (SHEA) and the infectious diseases society of America (IDSA). Infect Control Hosp Epidemiol, 2010. 31(5): p. 431-55.