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

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.