Cumulative effects of several nonenzymatic mechanisms on the resistance of Pseudomonas aeruginosa to aminoglycosides
Cumulative effects of several nonenzymatic mechanisms on the resistance of Pseudomonas aeruginosa to aminoglycosides
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DOI：
10.1128/aac.00704-06
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发表时间：
2007-03-01
影响因子：
4.9
通讯作者：
Plesiat, Patrick
中科院分区：
文献类型：
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作者：
El'Garch, Farid;Jeannot, Katy;Plesiat, Patrick
对野生型铜绿假单胞菌菌株PAO1构建的Tn5-Hg插入文库（12,000个克隆）进行筛选，鉴定出4个基因（即galU、nuoG、mexZ和rplY），这些基因的破坏分别导致对氨基糖苷类的抗性增加（平均为2倍）。这些基因的失活分别与(i)外膜摄取受损，（ii）主动运输减少，（iii） mexxy - oprm介导的主动外排增加，以及（iv）氨基糖苷靶改变有关。此外，研究发现，编码核糖体蛋白L25的基因rplY的抑制可导致外排系统MexXY-OprM的适度上调和对β -内酰胺类抗生素的超敏感。双、三、四重突变体的构建证明了不同机制对氨基糖苷抗性的累积效应，与野生型菌株PA01相比，四重突变体的mic从16倍增加到64倍。总之，这些结果说明了铜绿假单胞菌如何通过内在（即非酶）机制逐渐对这些抗生素产生高耐药性，如在囊性纤维化患者中。
Screening of a Tn5-Hg insertional library (12,000 clones) constructed in wild-type Pseudomonas aeruginosa strain PAO1 identified four genes (namely, galU, nuoG, mexZ, and rplY) whose disruption individually led to increased resistance to aminoglycosides (means of twofold). Inactivation of these genes was associated with (i) impaired outer membrane uptake, (ii) reduced active transport, (iii) increased MexXY-OprM-mediated active efflux, and (iv) alteration of target of aminoglycosides, respectively. In addition, suppression of the gene rplY, which codes for ribosomal protein L25, was found to result in both moderate upregulation of the efflux system MexXY-OprM and hypersusceptibility to beta-lactam antibiotics. Construction of double, triple, and quadruple mutants demonstrated cumulative effects of the different mechanisms on aminoglycoside resistance, with MICs increasing from 16- to 64-fold in the quadruple mutant compared to the wild-type strain PA01. Altogether, these results illustrate how P. aeruginosa may gradually develop high resistance to these antibiotics via intrinsic (i.e., nonenzymatic) mechanisms, as in cystic fibrosis patients.