Recacha Esther, Fox Valeria, Díaz-Díaz Sara, García-Duque Ana, Docobo-Pérez Fernando, Pascual Álvaro, Rodríguez-Martínez José Manuel
Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena, Seville, Spain.
Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
Front Microbiol. 2021 Apr 7;12:653479. doi: 10.3389/fmicb.2021.653479. eCollection 2021.
Disbalancing envelope stress responses was investigated as a strategy for sensitization of to antimicrobial agents. Seventeen isogenic strains were selected from the KEIO collection with deletions in genes corresponding to the σ, Cpx, Rcs, Bae, and Psp responses. Antimicrobial activity against 20 drugs with different targets was evaluated by disk diffusion and gradient strip tests. Growth curves and time-kill curves were also determined for selected mutant-antimicrobial combinations. An increase in susceptibility to ampicillin, ceftazidime, cefepime, aztreonam, ertapenem, and fosfomycin was detected. Growth curves for Psp response mutants showed a decrease in optical density (OD) using sub-MIC concentrations of ceftazidime and aztreonam (Δ and Δ mutants), cefepime (Δ and Δ mutants) and ertapenem (Δ mutant). Time-kill curves were also performed using 1xMIC concentrations of these antimicrobials. For ceftazidime, 2.9 log (Δ mutant) and 0.9 log (Δ mutant) decreases were observed at 24 and 8 h, respectively. For aztreonam, a decrease of 3.1 log (Δ mutant) and 4 log10 (Δ mutant) was shown after 4-6 h. For cefepime, 4.2 log (Δ mutant) and 2.6 log (Δ mutant) decreases were observed at 8 and 4 h, respectively. For ertapenem, a decrease of up to 6 log (Δ mutant) was observed at 24 h. A deficient Psp envelope stress response increased susceptibility to beta-lactam agents such as cefepime, ceftazidime, aztreonam and ertapenem. Its role in repairing extensive inner membrane disruptions makes this pathway essential to bacterial survival, so that disbalancing the Psp response could be an appropriate target for sensitization strategies.
研究了破坏包膜应激反应作为使细菌对抗菌剂敏感化的一种策略。从KEIO文库中选择了17个同基因菌株，这些菌株对应于σ、Cpx、Rcs、Bae和Psp反应的基因存在缺失。通过纸片扩散法和梯度纸条试验评估了对20种具有不同靶点的药物的抗菌活性。还测定了选定的突变体-抗菌剂组合的生长曲线和时间杀菌曲线。检测到对氨苄西林、头孢他啶、头孢吡肟、氨曲南、厄他培南和磷霉素的敏感性增加。使用低于最低抑菌浓度（sub-MIC）的头孢他啶和氨曲南（Δ和Δ突变体）、头孢吡肟（Δ和Δ突变体）以及厄他培南（Δ突变体）时，Psp反应突变体的生长曲线显示光密度（OD）降低。还使用这些抗菌剂的1倍最低抑菌浓度（1xMIC）进行了时间杀菌曲线测定。对于头孢他啶，在24小时和8小时分别观察到2.9个对数（Δ突变体）和0.9个对数（Δ突变体）的下降。对于氨曲南，在4 - 6小时后显示下降了3.1个对数（Δ突变体）和4个对数（Δ突变体）。对于头孢吡肟，在8小时和4小时分别观察到4.2个对数（Δ突变体）和2.6个对数（Δ突变体）的下降。对于厄他培南，在24小时观察到下降高达6个对数（Δ突变体）。Psp包膜应激反应缺陷增加了细菌对头孢吡肟、头孢他啶、氨曲南和厄他培南等β-内酰胺类药物的敏感性。其在修复广泛的内膜破坏中的作用使该途径对细菌生存至关重要，因此破坏Psp反应可能是敏感化策略的合适靶点。
