Antibacterial activity of Vaccinium vitis-idaea L
Antibacterial effect of the water, ethanol and ethyl acetate of Vaccinium vitis idaeae fructus (Ericaceae) were investigated in vitro against eleven strains of Escherichia coli. The following strains of bacteria were tested: ten strains which are clinical isolates (MFBl-376, MFBl-441, MFBl-412, MFBl-218, MFBl-29310, MFBl-027, MFBl-255, MFBl-413, MFBl-343, MFBl-228) and standard strain of E. coli ATCC 25922 as control. The effect on bacteria was determined by tube dilution method. All tested extracts showed antibacterial activity. Based on the minimal inhibitory concentrations (MIC), the ethyl acetate extract showed the strongest activity for all strains (10mg/ml). MICs of water extracts were 20mg/ml for all strains except E. coli MFBl-441 (MIC 10mg/ml). MICs of ethanol extract were 10mg/ml for all strains except E. coli MFBl-218 (20mg/ml). Ethyl acetate extract was chosen to investigate the effects of its combinations with commercial antibiotics amoxicillin/ciprofloxacin by checkerboard method. Results showed that the interactions between extract and amoxicillin were synergistic (E. coli MFBl-376, 413, 228) and additive effects (E. coli MFBl-441, 343, 29310, 027, 218, 412, 255 and control strain E. coli ATCC 25922) against the tested bacteria. Synergism was confirmed at an amoxicillin concentration corresponding to ¼ MIC and ethyl acetate extract concentrations were to ¼ MIC and lower for strains E. coli MFBl-376 and MFBl-413. For strain E. coli MFBl-228 synergism was confirmed at an amoxicillin concentrations were to ¼ MIC and lower and extract concentrations were to ¼ MIC and lower. Interactions between ethyl acetate extract and ciprofloxacin were synergistic (E. coli MFBl-413) and additive (E. coli MFBl-29310, 027, 343, 441, 412, 228, 376, 218, 255 and control strain E. coli ATCC 25922). Synergism was observed in relation to strain E. coli MFBl-413, ciprofloxacin concentrations were ¼ MIC and lower and extract concentrations were ¼ MIC and lower.