Unidad de Enfermedades Infecciosas y Microbiología, Hospital Universitario Virgen Macarena, Seville, Spain.
Departamento de Microbiología, Facultad de Medicina, Universidad de Sevilla, Seville, Spain.
Antimicrob Agents Chemother. 2023 Mar 16;67(3):e0139222. doi: 10.1128/aac.01392-22. Epub 2023 Feb 21.
The suppression of the SOS response has been shown to enhance the activity of quinolones. Furthermore, Dam-dependent base methylation has an impact on susceptibility to other antimicrobials affecting DNA synthesis. Here, we investigated the interplay between these two processes, alone and in combination, in terms of antimicrobial activity. A genetic strategy was used employing single- and double-gene mutants for the SOS response ( gene) and the Dam methylation system ( gene) in isogenic models of Escherichia coli both susceptible and resistant to quinolones. Regarding the bacteriostatic activity of quinolones, a synergistic sensitization effect was observed when the Dam methylation system and the gene were suppressed. In terms of growth, after 24 h in the presence of quinolones, the Δ Δ double mutant showed no growth or delayed growth compared to the control strain. In bactericidal terms, spot tests showed that the Δ Δ double mutant was more sensitive than the Δ single mutant (about 10- to 10-fold) and the wild type (about 10- to 10-fold) in both susceptible and resistant genetic backgrounds. Differences between the wild type and the Δ Δ double mutant were confirmed by time-kill assays. The suppression of both systems, in a strain with chromosomal mechanisms of quinolone resistance, prevents the evolution of resistance. This genetic and microbiological approach demonstrated the enhanced sensitization of E. coli to quinolones by dual targeting of the (SOS response) and Dam methylation system genes, even in a resistant strain model.
SOS 反应的抑制已被证明可以增强喹诺酮类药物的活性。此外，Dam 依赖性碱基甲基化会影响其他影响 DNA 合成的抗菌药物的敏感性。在这里，我们研究了这两个过程单独和联合作用时在抗菌活性方面的相互作用。采用遗传策略，在对喹诺酮类药物敏感和耐药的大肠杆菌同基因模型中，使用 SOS 反应（ gene）和 Dam 甲基化系统（ gene）的单基因和双基因突变体。关于喹诺酮类药物的抑菌活性，当抑制 Dam 甲基化系统和 基因时，观察到协同敏化作用。在生长方面，在用喹诺酮类药物处理 24 小时后，与对照菌株相比，ΔΔ 双突变体没有生长或生长延迟。在杀菌方面，点测试表明，与野生型相比，ΔΔ 双突变体在敏感和耐药遗传背景下都更敏感（约 10 到 10 倍）和Δ 单突变体（约 10 到 10 倍）。通过时间杀伤测定证实了野生型和 ΔΔ 双突变体之间的差异。在具有染色体水平喹诺酮类药物耐药机制的菌株中，抑制这两个系统可防止耐药性的进化。这种遗传和微生物学方法表明，即使在耐药菌株模型中，通过靶向 SOS 反应（）和 Dam 甲基化系统基因的双重作用，大肠杆菌对喹诺酮类药物的敏感性增强。
