CpxR overexpression increases the susceptibility of acrB and cpxR double-deleted Salmonella enterica serovar Typhimurium to colistin
CpxR overexpression increases the susceptibility of acrB and cpxR double-deleted Salmonella enterica serovar Typhimurium to colistin
复制标题
CpxR 过表达增加 acrB 和 cpxR 双缺失鼠伤寒肠沙门氏菌对粘菌素的敏感性
DOI：
10.1093/jac/dky320
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发表时间：
2018-11-01
影响因子：
5.2
通讯作者：
Hu, Gongzheng
中科院分区：
文献类型：
--
作者：
Zhai, Ya-Jun;Huang, Hui;Hu, Gongzheng
背景：结肠素已被用作人类MDR革兰氏阴性细菌感染的最后一个治疗胜地。据报道，两组分系统CPXAR有助于细菌的MDR。与先前所理解的CPXAR有关，可能有一个更复杂的网络，这是有助于肠菌素易感性的。方法：一系列的ACRB或CPXR妄想突变体的多种敏感性标准菌株在我们以前的研究中（我们以前的研究）（Salmonella typhimurium）在我们先前的研究中被构造出来。 。通过2倍连续汤微稀释法测定肠菌素的MIC。用各种浓度的大肠菌素进行了时间杀伤和生存测定。通过LB和M9-葡萄糖（0.2％）最小培养基中的OD600或CFU计数测量生长曲线和饥饿存活率。定量RT-PCR用于确定靶基因的mRNA表达水平。结果：结果表明，CPXR过表达的JS Delta delta acrb delta cpxr :: kan/pcpxr的cpxr菌素MIC大幅降低（0.05 mg/l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l L/l ）比JS（0.8 mg/L）和JS Delta ACRB三角洲（Delta Acrb Delta cpxr :: kan（0.8 mg/l）。结肠蛋白时间杀伤和生存分析表明，JS Delta Acrb Delta CPXR :: KAN/PCPXR更容易受到Colistin（0.05 mg/L）的影响，但与JSDACRBDCPXR :: kan相比，在延长饥饿应力方面的生存能力更高。此外，发现与结肠蛋白抗性相关基因的表达水平（PHOP，PHOQ，PMRB，PMRB，PMRC，PMRH和PMRD）明显下调，负调控蛋白MGRB显着上调。 CPXR可以通过PMRAB和PHOPQ调节来调节沙门氏菌伤寒沙门氏菌的易感性系统。
Background
Colistin has been used as the last therapeutic resort for treatment of MDR Gram-negative bacteria infections in humans. The two-component system CpxAR has been reported to contribute to the MDR of bacteria. There may be a more complex network mediated by CpxAR contributing to colistin susceptibility than previously understood.
Methods
A series of AcrB or CpxR deletion mutants of a multidrug-susceptible standard strain of Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) was constructed in our previous study. MICs of colistin were determined by the 2-fold serial broth microdilution method. Time-kill and survival assays were carried out with various concentrations of colistin. Growth curves and starvation survival were measured by OD600 or cfu count in LB and M9-glucose (0.2%) minimum media. Quantitative RT-PCR was used to determine the mRNA expression levels of target genes.
Results
The results showed that the MIC of colistin for the CpxR-overexpressed strain JSΔacrBΔcpxR::kan/pcpxR was dramatically decreased (0.05 mg/L) by 16-fold compared with JS (0.8 mg/L) and JSΔacrBΔcpxR::kan (0.8 mg/L). Colistin time-kill and survival assays showed that JSΔacrBΔcpxR::kan/pcpxR was more susceptible to colistin (0.05 mg/L), but had a considerably higher survivability regarding prolonged starvation stress compared with JSΔacrBΔcpxR::kan. Furthermore, the expression levels of colistin resistance-related genes (phoP, phoQ, pmrB, pmrC, pmrH and pmrD) were found to be remarkably down-regulated and the negative regulatory protein mgrB was significantly up-regulated.
Conclusions
This study demonstrated that CpxR may regulate the colistin susceptibility of Salmonella Typhimurium through the PmrAB and PhoPQ regulatory systems.