Payne S M, Finkelstein R A
J Clin Invest. 1978 Jun;61(6):1428-40. doi: 10.1172/JCI109062.
The ability of potential pathogens to acquire iron in a host is an important determinant of both their virulence and the nature of the infection produced. Virulent gram-negative bacteria are capable of acquiring sufficient iron from the host because their virulence (for chick embryos) is unaffected by exogenous iron. Avirulent mutants which are apparently limited in their ability to acquire iron could be isolated from the virulent strains. The lethality of these mutants was significantly enhanced by exogenous iron. Reduction of the relatively high serum iron saturation of chick embryos (to levels more closely approximating those in man) by pretreatment with iron-binding proteins or endotoxin inhibits the lethality of some virulent bacteria. Those bacteria whose virulence was reduced include the Shigella, Vibrio cholerae and strains of Neisseria gonorrhoeae, all of which are nondisseminating pathogens in the normal human host. Pathogens which produce septicemic and disseminating infections such as Neisseria meningitidis, Haemophilus influenzae type B, Escherichia coli possessing K-1 antigen, Pseudomonas aeruginosa and Salmonella typhimurium and disseminating strains of N. gonorrhoeae were, in general, unaffected by reduced serum iron saturation. These disseminating bacteria appeared to produce greater quantities of compounds (siderophores) which stimulated microbial growth in low-iron media than did the nondisseminating pathogens. Thus, the gram-negative bacteria tested can be divided into four major classes according to their responses to modifications in iron levels in the chick embryo model and these results correlate with the nature of the infections which they typically produce in man.
潜在病原体在宿主体内获取铁的能力是其毒力以及所引发感染性质的重要决定因素。致病性革兰氏阴性菌能够从宿主体内获取足够的铁，因为它们的毒力（对鸡胚而言）不受外源性铁的影响。从致病菌株中可以分离出铁获取能力明显受限的无毒突变体。外源性铁显著增强了这些突变体的致死性。通过用铁结合蛋白或内毒素预处理降低鸡胚相对较高的血清铁饱和度（使其更接近人类的水平），可抑制某些致病细菌的致死性。毒力降低的细菌包括志贺氏菌、霍乱弧菌和淋病奈瑟菌菌株，这些在正常人类宿主中都是非播散性病原体。一般来说，引发败血症和播散性感染的病原体，如脑膜炎奈瑟菌、B 型流感嗜血杆菌、具有 K - 1 抗原的大肠杆菌、铜绿假单胞菌和鼠伤寒沙门氏菌以及淋病奈瑟菌的播散菌株，不受血清铁饱和度降低的影响。与非播散性病原体相比，这些播散性细菌似乎能产生更多刺激低铁培养基中微生物生长的化合物（铁载体）。因此，根据它们对鸡胚模型中铁水平变化的反应，所测试的革兰氏阴性菌可分为四大类，这些结果与它们在人类中通常引发的感染性质相关。
