School of Pharmacy, Shanxi Medical University, Taiyuan, Shanxi, People's Republic of China.
Department of Pharmacy, Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, People's Republic of China.
J Glob Antimicrob Resist. 2017 Sep;10:113-119. doi: 10.1016/j.jgar.2017.04.008. Epub 2017 Jul 17.
The objective was to investigate how deficient of quorum sensing system (QS) affects minimal inhibitory concentrations (MICs) of Pseudomonas aeruginosa strains to ciprofloxacin (CIP) and levofloxacin (LEV) in vitro.
Collected the clinical Pseudomonas aeruginosa isolates. Screened the strains deficient of QS genes by the PCR agarose electrophoresis, and then randomly picked out normal strains with the same number of deficient ones. All strains incubated on the different CIP-concentration Mueller-Hinton agars for five days, the different concentrations of CIP respectively refered to 0.5×MIC, 1×MIC, 2×MIC and 4×MIC. Strains incubated on the first, third and fifth days were saved. MICs of saved strains to CIP and LEV were measured by the agar dilution method. Statistical analysis methods were the repeated measures analysis of variance and the rank sum test.
The study totally collected 40 Pseudomonas aeruginosa isolates. 5 deficient strains screened were as follows: one strain lacked of rhlR and lasI genes, one strain lacked of lasI, lasR, rhlI and rhlR genes, four strains lacked of lasR gene. All the final selected strains were sensitive to both CIP and LEV. Statistical analysis results showed deficient strains became resistant more slowly and difficultly than normal strains, whether the resistance was to CIP or LEV. What's more, MICs to LEV showed the half and delayed increase than those to CIP in the vitro selection.
Deficient of QS inhibits the resistance selection of P. aeruginosa to CIP and LEV in vitro.
研究群体感应系统（QS）缺陷如何影响铜绿假单胞菌对环丙沙星（CIP）和左氧氟沙星（LEV）的最小抑菌浓度（MIC）。
收集临床分离的铜绿假单胞菌。通过 PCR 琼脂糖电泳筛选 QS 基因缺陷株，然后随机挑选相同数量的正常株。将所有菌株分别在不同 CIP 浓度的 Mueller-Hinton 琼脂上孵育 5 天，CIP 的不同浓度分别为 0.5×MIC、1×MIC、2×MIC 和 4×MIC。在第 1、3 和 5 天保存培养的菌株。用琼脂稀释法测定保存菌株对 CIP 和 LEV 的 MIC。统计分析方法为重复测量方差分析和秩和检验。
共收集 40 株铜绿假单胞菌。筛选出 5 株缺陷株，分别为：1 株缺失 rhlR 和 lasI 基因，1 株缺失 lasI、lasR、rhlI 和 rhlR 基因，4 株缺失 lasR 基因。所有最终选择的菌株对 CIP 和 LEV 均敏感。统计分析结果表明，QS 缺陷株比正常株更难更慢地产生对 CIP 和 LEV 的耐药性。此外，体外选择时 LEV 的 MIC 比 CIP 的 MIC 增加了一半，且滞后。
QS 缺陷抑制了铜绿假单胞菌对 CIP 和 LEV 的体外耐药性选择。
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