In VitroAntimicrobial Activity of Ethanolic Extract of Polish Propolis against Biofilm FormingStaphylococcus epidermidisStrains

Abstract

The aim of the presented study was to examine the antimicrobial activity of ethanol extract of Polish propolis (EEPP) against biofilm-forming CoNS strainsin vitro. Our results revealed that EEPP displayed varying degrees of activity against CoNS with MIC values ranging from 1.56 to 0.78 mg/mL. The average MIC was 1.13 ± 0.39 mg/mL while calculated MIC50and MIC90values were 0.78 mg/mL and 1.56 mg/mL, respectively. The biofilm formation ability by all testedS. epidermidisstrains was inhibited at EEPP concentrations ranging from 0.39 to 1.56 mg/mL. The degree of reduction of AlamarBlue was directly associated with the proliferation ofS. epidermidisstrains. The increased proliferation ofS. epidermidisstrains was observed after 12 and 24 hours of incubation in the presence of EEPP concentrations ranging from 0.025 to 0.39 mg/mL. These results suggest that antimicrobial activities of EEPP againstS. epidermidisexpressed as the reduction of bacterial growth, reduction of biofilm formation ability, and the intensity of proliferation were significantly affected by incubation time and EEPP concentration used as well as the interactions between these factors.