Michéa-Hamzehpour M, Furet Y X, Pechère J C
Département de Microbiologie Médicale, Centre Médical Universitaire, Geneva, Switzerland.
Antimicrob Agents Chemother. 1991 Oct;35(10):2091-7. doi: 10.1128/AAC.35.10.2091.
Routes of quinolone permeation in Pseudomonas aeruginosa were investigated by using sparfloxacin as a prototype compound. [14C]sparfloxacin cell labeling was 13 to 28% lower in three protein D2-deficient mutants resistant to imipenem than in their imipenem-susceptible counterparts. In four impermeability-type quinolone-resistant strains isolated from pefloxacin-treated animals, we observed two- to fourfold-greater resistance to imipenem, reduced protein D2 expression in the outer membrane according to Western blotting (immunoblotting), and 25 to 29% decreased cell labeling with imipenem. In a protein D2-producing strain but not in its protein D2-deficient isogenic mutant, uptake of [14C]sparfloxacin was strongly inhibited by L-lysine and imipenem, which act as substrates for protein D2. Conversely, binding of [14C]imipenem in a porin D2-positive strain was reduced by sparfloxacin but not by the nonamphoteric quinolone nalidixic acid. Sparfloxacin, imipenem, and lysine possess a carboxyl group and a potentially protonated nitrogen separated from each other by 0.64 to 1.07 nm as calculated by computer. Hence, protein D2 may catalyze facilitated diffusion for sparfloxacin, as it does for imipenem. In addition, pefloxacin-selected isolates contained 41 to 113% more 3-deoxy-D-mannooctulosonic acid than their quinolone-susceptible counterparts, with MIC increases of 2- to 4-fold for WIN-57273 (n-octanol-phosphate buffer partition coefficient, 13.139), 4- to 8-fold for difloxacin (partition coefficient, 3.093) and sparfloxacin (partition coefficient, 0.431), and 8- to 16-fold for norfloxacin (partition coefficient, 0.059) and ciprofloxacin (partition coefficient, 0.056). Thus, we hypothetize that in quinolone-selected strains, increased amounts of lipopolysaccharide form a permeability barrier that acts preferentially against hydrophilic quinolones.
以司帕沙星作为原型化合物，研究了喹诺酮在铜绿假单胞菌中的渗透途径。与对亚胺培南敏感的菌株相比，三种对亚胺培南耐药的蛋白D2缺陷型突变体中，[14C]司帕沙星的细胞标记率低13%至28%。在从培氟沙星治疗的动物中分离出的四株非渗透性喹诺酮耐药菌株中，我们观察到它们对亚胺培南的耐药性提高了2至4倍，根据蛋白质印迹法（免疫印迹），外膜中蛋白D2的表达降低，并且亚胺培南的细胞标记率降低了25%至29%。在一株产生蛋白D2的菌株中，但在其蛋白D2缺陷的同基因突变体中则不然，作为蛋白D2底物的L-赖氨酸和亚胺培南强烈抑制了[14C]司帕沙星的摄取。相反，司帕沙星可降低在孔蛋白D2阳性菌株中[14C]亚胺培南的结合，但非两性喹诺酮萘啶酸则无此作用。通过计算机计算，司帕沙星、亚胺培南和赖氨酸都具有一个羧基和一个潜在的质子化氮，它们彼此之间相隔0.64至1.07纳米。因此，蛋白D2可能像催化亚胺培南那样，催化司帕沙星的易化扩散。此外，培氟沙星选择的分离株中3-脱氧-D-甘露糖辛酸的含量比其喹诺酮敏感的对应菌株多41%至113%，WIN-57273（正辛醇-磷酸盐缓冲液分配系数，13.139）的最低抑菌浓度增加了2至4倍，二氟沙星（分配系数，3.093）和司帕沙星（分配系数，0.431）增加了4至8倍，诺氟沙星（分配系数，0.059）和环丙沙星（分配系数，0.056）增加了8至16倍。因此，我们推测在喹诺酮选择的菌株中，脂多糖含量的增加形成了一个通透性屏障，该屏障优先作用于亲水性喹诺酮。
