IN VITRO ANTIBACTERIAL EFFECT OF CHILEAN PROPOLIS (Gr. própolis) EXTRACT ON DIFFERENT LEVELS ON Escherichia coli AND Lactobacillus acidophilus.

Objectives: Determine the in vitro antibacterial effect of Chilean propolis extract in different concentrations of Lactobacillus acidophilus and Escherichia coli.
Methods: The matrix solution was prepared by dissolving propolis in alcohol. Subsequently the solutions of 5, 15, 25, 50, 75 and 100% were prepared. Bacteria were grown in broth for 48 hours; Escherichia coli in Trypticase broth and Lactobacillus acidophilus in Rogosa broth, afterwards broth was diluted and was compared to McFarlan reagent, then Escherichia coli was sown in Trypticase agar and Lactobacillus acidophilus in Rogosa agar with each concentration. Later a well was prepared and 50 µL of each solution was added. The same procedure with sterile distilled water was performed as negative control. The positive control consisted of chlorhexidine and 70% alcohol to rule that the antibacterial effect took place. The consecutive growth waited for 48 hours and the zone of inhibition was measured. Finally serial dilutions are performed to confirm growth inhibition.
Results: The propolis solution 25, 50, 75 and 100% has no significant differences with chlorhexidine on Lactobacillus acidophilus.
The propolis solution 50, 75 and 100% has not significant differences with chlorhexidine on Escherichia coli.
The antibacterial effect of alcohol on bacteria was not observed.
Data was analyzed using a Statistical Dunn test, with a significance level of 5%.
Conclusions: The antibacterial effect on Lactobacillus acidophilus and Escherichia coli is produced by propolis, and the antibacterial effect of alcohol was discarded.