In vitro evaluation of antibacterial properties of propolis alcoholic extract on bovine mastitis isolates

This study aimed to investigate the antibacterial effect of propolis alcoholic extract on the number of bovine mastitis isolates. For this purpose, agar disk diffusion method for determination of bacterial sensitivity and dilution method for determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) was used separately. The results of bacterial sensitivity test in the case of the standard antibiotics of tetracycline, amikacine and also disks impregnated with alcoholic extracts of propolis showed that the diameter of inhibition zone created by the mentioned combination about all of tested isolates was far larger and this difference about Escherichia coli and Klebsiella pneumonia isolates, was significant (p<0.05). Also the results of MIC and MBC tests indicated that the inhibition of bacterial growth by alcoholic extract of propolis had a direct relationship with the amount of available propolis in the dilution and increasing of propolis in each dilution, reduced the number of cultured bacterial colonies and no bacterial growth was observed in the dilution equivalent to MBC of propolis. Therefore, it seems that constitutes of this natural compound could be used as effective antibacterial agents against a wide range of bacteria causing bovine mastitis instead of using synthetic antibiotics.