In vitro antimicrobial activity of propolis against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium

Turkish propolis extracts have antibacterial activity on a range of commonly encountered Gram-positive cocci. In the present study, the anti-bacterial efficiency of three ethanol extracts of propolis (EEPs) sampled from Mamak, Kemaliye 1 and Kemaliye 2 regions of Turkey was evaluated. Minimal inhibitory concentrations (MICs) of the three EEPs were determined on 33 methicillin-resistant Staphylococcus aureus (MRSA) and 33 vancomycin-resistant Enterococcus faecium (VREF) clinical isolates by a macrodilution broth method. The MICs for MRSA and VREF isolates of EEPs sampled from Mamak, Kemaliye 1 and Kemaliye 2 regions were in the range of 7.8-31.2 μg/ml, 70.3-281.2 μg/ml, and 17.5-140.4 μg/ml, respectively. All three EEPs were more effective against MRSA than VREF (p<0.05). EEP sampled from Mamak had the lowest MIC for MRSA (p < 0.001) and VREF (p < 0.05). These data demonstrated that EEP sampled from Turkey possess potent antimicrobial activity, providing an alternative therapy against infections caused by resistant strains such as VREF and MRSA.