新疆动物源大肠杆菌小菌落变异体生物学特性分析

Biological characterization of small colony variants (SCVs) of Escherichia coli from animals in Xinjiang Uygur Autonomous Region of China

摘要:

【背景】小菌落变异体(small colony variants, SCVs)在细菌耐药和持续残留等过程中发挥着重要作用，但目前国内鲜有动物源大肠杆菌(Escherichia coli, EC) SCVs的相关报道。【目的】对新疆动物源EC-SCVs的生物学特性进行对比研究分析，为国内EC-SCVs的相关研究提供基础数据。【方法】使用氨基糖苷类抗生素对新疆动物源大肠杆菌进行诱导，使其形成SCVs。然后对野生株和诱导株进行培养特征、生化特性、药物敏感性、运动力、生物被膜和溶血活性等生物学特性检测。【结果】经卡那霉素和庆大霉素诱导，从牛、羊和马源大肠杆菌中得到5株EC-SCVs (2 株为血红素依赖型，3株未知其营养依赖型)。与野生株相比，EC-SCVs的生化特性改变，所有EC-SCVs转变为不利用醋酸盐，在不同培养基中的培养特征也存在差异。并且对氨基糖苷类抗生素的耐受性增强，生物被膜形成能力增强，但运动力下降。除血红素依赖型EC-SCVs的溶血活性增强外，其他SCVs的溶血活性并无差异。【结论】动物源EC-SCVs的生物学特性与野生株相比有较大差异，这些生物学特性的改变可能会给大肠杆菌致病或耐药等方面的防治带来更大挑战，其相关机制还有待深入研究。

关键词:大肠杆菌;小菌落变异体;生物学特性

Abstract:

[Background] Small colony variants (SCVs) play a role in the antibiotic resistance and persistent residues of bacteria, while little is known about the Escherichia coli (EC) SCVs from animals in China. [Objective] To study the biological characteristics of EC-SCVs from animals in Xinjiang Uygur Autonomous Region of China, so as to provide basic data for the related studies of EC-SCVs. [Methods] EC from the animals in Xinjiang Uygur Autonomous Region of China was induced with aminoglycosides to form SCVs. The cultural characteristics, biochemical properties, susceptibility to antibiotics, motility, biofilm formation, and hemolytic activities of the wild type and SCVs were examined. [Results] Five strains of EC-SCVs (2 heme-dependent and 3 unknown nutrient-dependent) were obtained from bovine, sheep, and horse by induction with kanamycin or gentamicin. EC-SCVs showed different biochemical characteristics from the wild type. All the EC-SCVs did not utilize acetate and showed varied cultural characteristics in different media. Moreover, they presented enhanced tolerance to aminoglycosides, increased biofilm formation, and decreased motility. Except that the hemolytic activity of heme-dependent EC-SCVs enhanced, the hemolytic activities of other SCVs changed little. [Conclusion] The biological properties of animal-derived EC-SCVs are different from those of the wild type, and these changes may pose great challenges to the prevention and control of the infectivity or drug resistance of E. coli. The related mechanisms remain to be studied in depth.

Key words:Escherichia coli;small colony variants;biological characteristics