In vitro and in vivo bioluminescent imaging to evaluate anti-Escherichia coli activity of Galla Chinensis

Abstract

BackgroundNovel and rapid technology is urgently needed to expedite screening of new antibacterial drugs for preventing and treating life-threatening bacterial infection. PurposeThis study applied bioluminescent imaging to evaluate the antibacterial activity of Galla Chinensis extract (GCE) in gastrointestinal tracts of mice. MethodsBioluminescent Escherichia coli (E. coli) was constructed by transforming plasmid DNA containing TATA box-driven luciferase gene. The antibacterial activity of GCE in vitro was evaluated by mixing GCE and bioluminescent E. coli and subjecting to image; the antibacterial efficacy of GCE was evaluated in vivo by administering intragastric GCE and bioluminescent E. coli to mice and subjecting to image at 2 hours. ResultsGCE inhibited the growth of E. coli in a dose-dependent manner, with a minimal inhibitory concentration of 4 μg/μL and a minimal bactericidal concentration of 8 μg/μL. Intragastric administration of bioluminescent E. coli showed that a strong luminescent signal was observed in the abdominal region, while GCE treatment significantly decreased bioluminescence. Ex vivo image and bacterial count verified the decreased intensity of bioluminescence and number of viable E. coli in the intestines of GCE-treated mice. ConclusionThe findings suggest: (1) GCE exhibits anti-E. coli activities in vitro and in vivo; and (2) the feasibility of bioluminescent imaging on real-time monitoring of the antibacterial effects of natural products in living mice.