title: Antimicrobial activity of propolis special extract GH 2002 against multidrug-resistant clinical isolates.
abstract: The need to discover and develop alternative therapies to treat multidrug-resistant bacterial infections is timely. The aim of this study was to examine the antimicrobial potential of propolis, as a purified and concentrated special extract GH 2002, against clinical isolates of Streptococcus pyogenes, methicillin-resistent Stapylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE) and Candida. Minimal inhibitory concentrations (MICs) and minimal microbicidial concentrations (MMCs) of propolis against microbial pathogens were evaluated using the broth microdilution method. Propolis extract GH 2002 revealed low MICs in the range of 0.03 to 2 mg/ml against S. pyogenes, S. aureus, E. faecium and Candida. A high bactericidal activity of propolis extract in the range of 0.06 to 1.0 mg/ml was determined for S. pyogenes and S. aureus, however propolis was not bactericidal against E. faecium. Propolis concentrations between 0.6 and 2.4 mg/ml displayed fungicidal activity against different Candida species. Whereas all tested MRSA strains were highly susceptible against propolis, only minor activity was found against VRE strains. Time-kill curves demonstrated a high antimicrobial activity at low MICs already after few hours of incubation against reference strains, clinical antibiotic-susceptible strains, clinical antifungal susceptible strains as well as all tested clinical MRSA strains, but not against VRE strains. In conclusion, clinical drug-sensitive as well as some clinical multidrug-resistant microbial isolates, i.e. MRSA, were susceptible to propolis with different degrees of susceptibility. These results suggest that the special propolis extract GH2002 might be used in the development of alternative products for therapy of microbial infections.
authors.affiliation: Department of Infectious Diseases, Virology, University of Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Astani
authors.forename: S
authors.initials: S
authors.lastname: Zimmermann
authors.forename: E
authors.initials: E
authors.lastname: Hassan
authors.forename: J
authors.initials: J
authors.lastname: Reichling
authors.forename: K H
authors.initials: KH
authors.lastname: Sensch
authors.forename: P
authors.initials: P
authors.lastname: Schnitzler
mesh_terms: D000890:Anti-Infective Agents; D002175:Candida / Q000187:drug effects; D025141:Drug Resistance, Fungal / Q000187:drug effects*; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects*; D016984:Enterococcus faecium / Q000187:drug effects; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D011429:Propolis / Q000494:pharmacology*; D013297:Streptococcus pyogenes / Q000187:drug effects; D020713:Vancomycin Resistance
chemical_list: D000890:Anti-Infective Agents; D011429:Propolis