肺炎克雷伯菌促进环丙沙星的耐药性及其与氧化应激相关的机制研究

目的：探讨肺炎克雷伯菌基因多态性与环丙沙星的耐药性联系。方法：收集肺炎克雷伯菌77株，依据是否产铁载体将菌株分为高产铁载体组（n=38）和低产铁载体组（n=39）。测定细菌铁载体产量和对环丙沙星的药物敏感性；对菌株GyrA基因和AcrAB外排泵基因测序分析基因表型与耐药之间的联系；分析了加入Fe³⁺后环丙沙星MIC值的变化。在添加Fe³⁺和环丙沙星前后检测细菌氧化应激水平的变化。结果：在高产铁载体组中，细菌对环丙沙星的耐药率为54%，显著高于低产组（P<0.05）。分析添加Fe³⁺后铁载体的产量与环丙沙星的耐药性（MIC值）呈正相关（P<0.05）。但铁载体相关耐药与GyrA变异没有相关性（P>0.05）。铁载体的高产菌株与低产菌株比较，氧化应激水平明显降低（P<0.05）。虽然环丙沙星能够对氧化应激水平产生明显的诱导作用（P<0.05），但是高产铁载体组细菌的氧化应激水平与低产组比较，明显变低（P<0.05）。结论：本研究发现肺炎克雷伯菌铁载体分泌量与环丙沙星耐药率正相关。

Klebsiella pneumoniae promotes ciprofloxacin resistance and its mechanisms associated with oxidative stress

OBJECTIVE To investigate the association between Klebsiella pneumoniae gene polymorphism and the drug resistance of ciprofloxacin. METHODS Totally 77 strains of Klebsiella pneumoniae were collected and divided into the high-yield iron carrier group (n=38) and the low-yield iron carrier group (n=39) according to whether or not iron carriers were produced.The bacterial iron carrier yield and drug sensitivity to ciprofloxacin were determined.The strain GyrA gene and AcrAB efflux pump gene sequencing method was used to analyze the relationship between gene phenotype and drug resistance.The change of the MIC value of ciprofloxacin after the addition of Fe³⁺ was analyzed. The change of oxidative stress level of the bacteria was detected before and after the addition of Fe³⁺ and ciprofloxacin. RESULTS In the high-yield iron carrier group,the resistance rate of the bacteria to ciprofloxacin was 54%,significantly higher than that in the low yield group (P<0.05).The yield of bacterial iron carrier was positively correlated with the drug resistance of ciprofloxacin (MIC value) (P<0.05).However, there was no correlation between iron carrier related resistance and GyrA mutation (P>0.05).The level of oxidative stress of the high-yield iron carrier group was significantly lower than that of the low-yield iron carrier group (P<0.05).Although ciprofloxacin could significantly induce oxidative stress (P<0.05), and the oxidative stress level of the high-yield iron carrier group was significantly lower than that of the low-yield group (P<0.05). CONCLUSION The secretion of iron carrier in Klebsiella pneumoniae is positively correlated with the drug resistance rate of ciprofloxacin.