In vitro antimicrobial activity of propolis dry extract

In this study the antibacterial and antifungal properties of propolis, a na tural product of bees, have been investigated against different pathogens. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentra tions (MBCs) were determined according to NCCLS standards on 320 strains in cluding Staphylococcus aureus, Group A beta-hemolytic streptococci, Strepto coccus pneumoniae, Moraxella catarrhalis, Haemophilus influenzae, Klebsiell a pneumoniae, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa a nd Candida albicans, Time-kill curves were assessed for susceptible microor ganisms, testing 0, 0.5, 1, 2, 4 x MIC for propolis, by counting viable bac teria after 0, 3, 6, 24 hours and viable yeasts after 0, 3, 6, 24 and 48 ho urs. Propolis showed good antimicrobial activity against most of the isolat es, particularly S. pneumoniae, H. influenzae and M. catarrhalis, but not a gainst Enterobacteriaceae. Time-kill curves demonstrated bacteriostatic rat her than bactericidal activity of propolis, the Latter being evident only a t high concentrations.