Ethanolic extract of propolis exerts a strong anti-bacterial activity, in addition to antifungal. antiviral and antiprotozoal properties. In previous studies from these laboratories we have demonstrated that the intensity of the bactericidal activity of E E P is correlated with the virulence of the mycobacteria tested, and that E E P has a synergistic effect with antibiotics on growth of staphylococcus aureus. In the present study we investigated whether the same synergism and correlation exists between E E P and some anti-tuberculosis drugs on tubercu losis mycobacteria with different degrees of virulence. Six standard strains and 11 wild strains of mycobacteria were exposed for 30 days to EEP, with or without streptomycin, rifamycin, isoniazid or ethambutol. Out of the 17 strains, 8 were resistant to at least two standard antibiotics, and were considered "multi-resistant strains". The rest were either susceptible or resistant to only one of the antimycobacterial drugs. Antagonism was recorded only in one case, when Staphylococcus aureus were treated with a mixture of E E P and ethambutol, sug gesting that a chemical bond could have been formed between this anti-tuberculosis anti biotic and one of the active components of the ethanol extract of propolis.

extract of propolis (EEP) has antibacterial, antiviral, antiprotozoal and antifungal properties, in addition to many biological effects. Our laboratory has demonstrated a syner­gistic effect of EEP and antibiotics on the growth of Staphylococcus aureus, and suggested that the bactericidal effect of EEP was expressed mainly on virulent mycobacteria rather than on non-virulent (attenuated) ones. The present study was designed to reconfirm the latter finding, by subjecting 17 different mycobacteria strains to EEP, and evaluating whether there is a correlation between the virulence of the mycobacteria strains studied and their susceptibility to EEP. Our findings demonstrate that while the four non-virulent strains studied are not susceptible to EEP, out of the 13 virulent strains studied seven are susceptible and six are resistant to it. These results suggest that while there is no full correlation between virulence of the mycobacteria tested and their susceptibility to EEP, the few strains that were resistant to EE P were non-virulent.