Stevens P, Young L S, Alam S
Diagn Microbiol Infect Dis. 1983 Sep;1(3):185-92. doi: 10.1016/0732-8893(83)90017-2.
The K-1 polysaccharide is an important virulence factor in human E. coli infections. Using E. coli 016K1, we investigated the kinetic association of bacteremia and K-1 antigenemia in acute lapine and canine infections and in a chronic infection model of neutropenic rats. Additionally, we assessed the presence of K-1 antigenemia in E. coli K-1 bacteremic patients. K-1 was measured by a solid phase radioimmunoassay (RIA) using cross-reactive equine anti-Group B meningococcal IgM. In acute infections, none of the dogs or rabbits developed antigenemia even with a bacteremia of 2 X 10(4) CFU/ml or 5 X 10(5) CFU/ml, respectively. Antigenemia appeared in the rabbit only with an infecting dose of greater than or equal to 5 X 10(8) CFU. In the rat model we observed an initial bacteremia of 10(3) CFU/ml, which increased to 10(6) CFU/ml at 24 hrs. However, antigenemia was most often delayed, appearing in only greater than or equal to 30 hrs postinfection. Percent mortality was directly associated with the degree of bacteremia and antigenemia. In acute human E. coli K-1 bacteremia, 11 of 22 (50%) of patients were positive for K-1 antigenemia. The data demonstrated that K-1 polysaccharide was not usually detectable in the early stages of bacteremia, but occurred only after prolonged infection or very high infecting doses. The RIA to measure K-1 antigenemia would not be a useful diagnostic tool.
K-1多糖是人类大肠杆菌感染中的一种重要毒力因子。我们使用大肠杆菌016K1，研究了急性兔和犬感染以及中性粒细胞减少大鼠慢性感染模型中菌血症与K-1抗原血症的动力学关联。此外，我们评估了大肠杆菌K-1菌血症患者中K-1抗原血症的情况。使用交叉反应的马抗B群脑膜炎球菌IgM通过固相放射免疫测定法（RIA）测量K-1。在急性感染中，即使犬和兔的菌血症分别达到2×10⁴CFU/ml或5×10⁵CFU/ml，它们也均未出现抗原血症。仅在感染剂量大于或等于5×10⁸CFU时，兔才出现抗原血症。在大鼠模型中，我们观察到初始菌血症为10³CFU/ml，在24小时时增加到10⁶CFU/ml。然而，抗原血症大多出现延迟，仅在感染后大于或等于30小时出现。死亡率与菌血症和抗原血症的程度直接相关。在急性人类大肠杆菌K-1菌血症中，22例患者中有11例（50%）K-1抗原血症呈阳性。数据表明，在菌血症早期通常检测不到K-1多糖，而是仅在长时间感染或非常高的感染剂量后才出现。测量K-1抗原血症的RIA不是一种有用的诊断工具。
