Time kill curve of bacteria isolated from milk of cows with mastitis to three ethanolic extracts of propolis

This study shows the effect of ethanolic extracts of propolis obtained by 70, 80 and 95% of ethanol on Staphylococcus aureus and Streptococcus agalactiae strains, isolated from milk of cows with mastitis. There were no significant differences (P>0.01) in the antibacterial activity among the three types of ethanolic extracts of propolis. The two concentrations of ethanolic extracts utilized in the sensitivity test of the Staphy/ococcus aureus, 3.0 and 2.0 mg/ml, were similar in the inhibition of the three strains tested. The bactericida! action of the ethanolic extracts of propolis was observed in only one strain, in both concentrations, from 12 hours of exposure. In the two strains of Streptococcus agalactiae, the bactericida! effect of propolis was observed at the end of 24 hours of exposure to 0.43 and 0.3 mg/ml concentrations. Dosages at least ten times smaller than those applied to Staphy/ococcus aureus caused a complete and irreversible inhibition of the Streptococcus aga/actiae, during the studied period. These results stimulate further investigations on the use of propolis extracts, using appropriate vehicles in bovine mastitis treatment.