Antibacterial mode of fibrauretine and synergistic effect with kanamycin against multi-drug resistant Escherichia coli.

Abstract

The present study evaluated the antibacterial activity and mode of action of fibrauretine on Escherichia coli (E. coli) and Staphylococcus aureus, and synergistic effect with kanamycin against multi-drug resistant E. coli. The fibrauretine exhibited inhibitory effect on the growth of the tested bacteria with minimum inhibitory concentration (MIC) and minimum bactericidal concentration of 2.5-5 and 5-10mg/ml, respectively. Morphological changes of cell microstructure were observed after adding fibrauretine at MIC. The mode of action was further confirmed by measuring release of 260-nm absorbing materials and extracellular potassium ions. Checkerboard dilution test suggested that fibrauretine exhibited synergistic activity when combined with kanamycin (FICI ranging from 0.5625 to 0.625). Our results indicated that fibrauretine exerted synergistic effect with kanamycin and its antibacterial mode of action mainly attributed to disruption of cell membrane integrity.