Abstract: Objective To observe the antibacterial effects of amikacin sulfate combined with the ingredient of coptis chinensis： the extract of coptis chinensis, berberine hydrochloride and palmatine hydrochloride on multiple drug resistance (MDR) of Escherichia coli (E.coli) in vitro. Methods One hundred strains of E.coli checked out from 2013 to 2014 that showed resistence to cefotaxime were selected, and in which MDR to bacteria were determined. The extended-spectrum β- lactamases (ESBLs)-producing by Kirby-Bauer test. The minimum inhibitory concentrations (MIC) of the extract of coptis chinensis, berberine hydrochloride, palmatine hydrochloride and amikacin sulfate on ESBLs- producing E.coli were determined firstly, and then the sterilization effects of amikacin sulfate combined with the other three medicines were observed by broth microdilution checkerboard method together with their fractional inhibitory concentrations (FIC), with ATCC 25922 for quality control strains. Results Ten MDR E.coli were screened and proved to be ESBLs-producing. The inhibitory effects were enhanced in a synergistic or additive pattern when amikacin sulfate combined with the extract of coptis chinensis, berberine hydrochloride on nine of the ten MDR E.coli in vitro, where the inhibitory effects were a synergistic or additive pattern when amikacin sulfate combined with palmatine hydrochloride on all of the MDR E.coli in vitro. Conclusion Palmatine hydrochloride or berberine hydrochloride or the extract of coptis chinensis combined with the amikacin sulfate has significant value in treatment of MDR E.coli, which is worthy of further study.

Key words: coptis, drugs, Chinese herbal, berberine, Escherichia coli, microbial sensitivity tests, drug therapy, combination, amikacin, palmatine hydrochloride