Antimicrobial Activity of Propolis from Tabora and Iringa Regions, Tanzania and Synergism with Gentamicin

Antimicrobial resistance (AMR) is among the threats to global public health, with developing countries being mostly affected. The AMR has undermined development of new antimicrobial agents by pharmaceutical industries despite new emerging infections. This necessitates a search for antimicrobial agents from resources available in developing countries. This study, therefore, aimed at assessing antimicrobial activity of two propolis samples from Iringa and Tabora, Tanzania. Ethanolic extracts of the two propolis samples were tested against standard microorganisms including, Gram +ve and Gram -ve bacteria and yeasts by determination of MICs using broth microdilution method. Synergism with Gentamicin was also assessed for one of the samples. Furthermore, HPTLC profiles of the extracts and presence of flavonoids were determined. The two propolis samples exhibited varied activity against the tested microorganisms with MICs ranging from 0.42 to 6.67mg/ml, with Tabora propolis being more active than Iringa propolis. Staphylococcus aureus was the most susceptible microorganism, while Pseudomonas aeruginosa was the most resistant. Propolis also potentiated the activity of Gentamicin. Both samples tested positive for flavonoids. However, there were some differences in their HPTLC profiles. We recommend further studies involving more samples of propolis from various regions of Tanzania to verify further the observed activity and synergism.