Allen P M, Fisher D, Saunders J R, Hart C A
Department of Microbiology, University of Liverpool, London.
J Med Microbiol. 1987 Dec;24(4):363-70. doi: 10.1099/00222615-24-4-363.
The behaviour of strains of Klebsiella aerogenes of capsular serotype K21 and strains of Escherichia coli producing a structurally related polysaccharide (colanic acid) was analysed by phagocytic and serum-killing assays. The cell-surface characteristics of these strains and of non-capsulate strains derived from them were also investigated by partitioning experiments in aqueous two-polymer phase systems. The possession of K21-type capsule by K. aerogenes or colanic-acid polysaccharide by E. coli conferred a strong negative charge on capsulate bacteria. Negatively charged bacteria of E. coli producing colanic-acid capsules, however, like non-capsulate K. aerogenes, were susceptible to uptake by polymorphonuclear leukocytes. In contrast, K21 polysaccharide conferred on klebsiellae considerable resistance to phagocytic uptake. The finding that ingested non-capsulate derivative strains of K. aerogenes were less rapidly degraded by phagocytes than E. coli strains suggested that other components of the cell surface of Klebsiella, notably lipopolysaccharide, may be involved in protection against phagocytic killing. The presence of colanic-acid capsules on E. coli conferred little resistance to the bactericidal activity of human serum or phagocytic uptake and did not protect against intracellular killing by polymorphonuclear leukocytes.
通过吞噬和血清杀菌试验分析了荚膜血清型K21的产气克雷伯菌菌株以及产生结构相关多糖（结肠酸）的大肠杆菌菌株的行为。还通过在水性双聚合物相系统中的分配实验研究了这些菌株及其衍生的无荚膜菌株的细胞表面特征。产气克雷伯菌拥有K21型荚膜或大肠杆菌拥有结肠酸多糖会使荚膜化细菌带上很强的负电荷。然而，产生结肠酸荚膜的带负电荷的大肠杆菌，与无荚膜的产气克雷伯菌一样，易被多形核白细胞摄取。相比之下，K21多糖赋予克雷伯菌对吞噬摄取的相当大的抗性。摄入的无荚膜产气克雷伯菌衍生菌株比大肠杆菌菌株被吞噬细胞降解的速度更慢，这一发现表明克雷伯菌细胞表面的其他成分，尤其是脂多糖，可能参与了抵御吞噬杀伤的过程。大肠杆菌上结肠酸荚膜的存在对人血清的杀菌活性或吞噬摄取几乎没有抗性，也不能防止被多形核白细胞进行细胞内杀伤。
