Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
Antimicrob Agents Chemother. 2012 Nov;56(11):5591-602. doi: 10.1128/AAC.01446-12. Epub 2012 Aug 20.
Screening of a transposon insertion mutant library of Pseudomonas aeruginosa for increased susceptibility to paromomycin identified a number of genes whose disruption enhanced susceptibility of this organism to multiple aminoglycosides, including tobramycin, amikacin, and gentamicin. These included genes associated with lipid biosynthesis or metabolism (lptA, faoA), phosphate uptake (pstB), and two-component regulators (amgRS, PA2797-PA2798) and a gene of unknown function (PA0392). Deletion mutants lacking these showed enhanced panaminoglycoside susceptibility that was reversed by the cloned genes, confirming their contribution to intrinsic panaminoglycoside resistance. None of these mutants showed increased aminoglycoside permeation of the cell envelope, indicating that increased susceptibility was not related to enhanced aminoglycoside uptake owing to a reduced envelope barrier function. Several mutants (pstB, faoA, PA0392, amgR) did, however, show increased cytoplasmic membrane depolarization relative to wild type following gentamicin exposure, consistent with the membranes of these mutants being more prone to perturbation, likely by gentamicin-generated mistranslated polypeptides. Mutants lacking any two of these resistance genes in various combinations invariably showed increased aminoglycoside susceptibility relative to single-deletion mutants, confirming their independent contribution to resistance and highlighting the complexity of the intrinsic aminoglycoside resistome in P. aeruginosa. Deletion of these genes also compromised the high-level panaminoglycoside resistance of clinical isolates, emphasizing their important contribution to acquired resistance.
对铜绿假单胞菌转座子插入突变体文库进行筛选，以寻找对巴龙霉素敏感性增加的突变体，发现了许多基因，这些基因的缺失会增强该菌对多种氨基糖苷类药物（包括妥布霉素、阿米卡星和庆大霉素）的敏感性。这些基因包括与脂质生物合成或代谢（lptA、faoA）、磷酸盐摄取（pstB）和双组分调节剂（amgRS、PA2797-PA2798）以及一个未知功能的基因（PA0392）有关的基因。这些基因缺失突变体表现出增强的泛氨基糖苷敏感性，而克隆基因可以逆转这种敏感性，这证实了它们对固有泛氨基糖苷耐药性的贡献。这些突变体没有表现出细胞包膜对氨基糖苷类药物通透性的增加，这表明增加的敏感性与由于包膜屏障功能降低而导致的氨基糖苷类药物摄取增加无关。然而，一些突变体（pstB、faoA、PA0392、amgR）在庆大霉素暴露后相对于野生型表现出细胞质膜去极化增加，这与这些突变体的膜更易受到干扰一致，可能是由于庆大霉素产生的翻译错误的多肽。这些耐药基因中的任意两个缺失突变体在各种组合中表现出的氨基糖苷类药物敏感性增加，与单个缺失突变体相比，这证实了它们对耐药性的独立贡献，并突出了铜绿假单胞菌固有氨基糖苷类耐药组的复杂性。这些基因的缺失也损害了临床分离株对高水平泛氨基糖苷类药物的耐药性，强调了它们对获得性耐药性的重要贡献。
