Hancock R E, Bell A
Department of Microbiology, University of British Columbia, Vancouver, Canada.
Eur J Clin Microbiol Infect Dis. 1988 Dec;7(6):713-20. doi: 10.1007/BF01975036.
Antibiotics taken up into gram-negative bacteria face two major diffusion barriers, the outer and cytoplasmic membranes. Of these, the former has been most studied and is discussed in detail here. Evidence from antibiotic MIC studies on porin-deficient mutants compared with their porin-sufficient parent strains has provided strong support for the proposal that some antibiotics, particularly beta-lactams, pass across the outer membrane through the water-filled channels of a class of proteins called porins. Nevertheless substantial evidence has accumulated for the importance of non-porin pathways of antibiotic uptake across the outer membranes of gram-negative bacteria. Examples discussed include the uptake of polycationic antibiotics via the self-promoted pathway, the uptake of hydrophobic antibiotics in some bacterial species and in mutants of others via the hydrophobic pathway, and the possible importance of poorly understood non-porin pathways of uptake of a variety of antibiotics. Other potential barriers to diffusion, including the cytoplasmic membrane, are briefly discussed.
进入革兰氏阴性菌的抗生素面临两个主要的扩散屏障，即外膜和细胞质膜。其中，前者研究得最多，在此将详细讨论。与具有孔蛋白的亲本菌株相比，针对缺乏孔蛋白的突变体进行抗生素最低抑菌浓度（MIC）研究所得出的证据，有力支持了以下观点：一些抗生素，尤其是β-内酰胺类抗生素，通过一类称为孔蛋白的蛋白质的充满水的通道穿过外膜。然而，大量证据表明革兰氏阴性菌外膜的非孔蛋白抗生素摄取途径也很重要。讨论的例子包括通过自促进途径摄取聚阳离子抗生素、某些细菌物种以及其他细菌突变体通过疏水途径摄取疏水抗生素，以及各种抗生素摄取的尚未完全了解的非孔蛋白途径的可能重要性。还简要讨论了包括细胞质膜在内的其他潜在扩散屏障。
