Fierer J, Finley F
J Infect Dis. 1979 Oct;140(4):581-9. doi: 10.1093/infdis/140.4.581.
When genetically serum-resistant Escherichia coli, Klebsiella pneumoniae, and Citrobacter freundii, but not Pseudomonas aeruginosa or Proteus mirabilis, were exposed to polymyxin B, they became susceptible to the bactericidal action of normal human and rabbit sera. In constrast, beta-lactam and aminoglycoside antibiotics did not render any serum-resistant bacteria serum-sensitive. Synergy between polymyxin B and the serum bactericidal system could be demonstrated by the addition of polymyxin B to bacteria in vitro, as well as to bacilli in serum from rabbits injected with the antibiotic. Polymyxin B-treated bacteria were killed by normal, lysozyme-depleted, C2-deficient, and hypogammaglobulinemic sera, but not by heated or C6-deficient sera. These findings indicate that polymyxin B-treated bacteria can be killed via the alternative complement pathway. However, C3 and C3b were detected on the surface of serum-resistant E. coli, regardless of whether the bacteria had been treated with polymyxin B. This observation suggests that a change in susceptibility to the alternative complement pathway was not the only explanation for the acquired serum sensitivity. Polymyxin B may also affect a step in the complement sequence beyond the activation of C3, a step that is apparently blocked in serum-resistant gram-negative bacteria.
当遗传性血清耐药的大肠杆菌、肺炎克雷伯菌和弗氏柠檬酸杆菌（但不是铜绿假单胞菌或奇异变形杆菌）暴露于多粘菌素B时，它们变得易受正常人及兔血清的杀菌作用影响。相比之下，β-内酰胺类和氨基糖苷类抗生素并不能使任何血清耐药菌对血清敏感。多粘菌素B与血清杀菌系统之间的协同作用可通过在体外将多粘菌素B添加到细菌中，以及添加到注射了该抗生素的兔血清中的杆菌中来证明。经多粘菌素B处理的细菌可被正常血清、溶菌酶缺乏血清、C2缺乏血清和低丙种球蛋白血症血清杀死，但不能被加热血清或C6缺乏血清杀死。这些发现表明，经多粘菌素B处理的细菌可通过替代补体途径被杀死。然而，无论细菌是否用多粘菌素B处理，在血清耐药大肠杆菌表面均检测到C3和C3b。这一观察结果表明，对替代补体途径敏感性的改变并非获得性血清敏感性的唯一解释。多粘菌素B也可能影响补体序列中C3激活之后的一个步骤，而这一步骤在血清耐药革兰氏阴性菌中显然被阻断。
