Synergistic Effect of Eucalyptus (Eucalyptus Camaldulensis) and Guava (Psidium Guajava) Ethanolic Extracts on Eschericia Coli and Staphylococcus Aureus

In-vitro antibacterial activities of the ethanolic leaf extracts of Eucalyptus camaldulensis and Psidium guajava and their combination were evaluated against Staphylococcus aureus, gram positive bacteria and Escherichia coli, gram negative bacteria using paper disc diffusion method. The extracts and their combination displayed broad spectrum activities against the test organisms with Eucalyptus camaldulensis leaf extract showing zone of inhibition of (18 mm) on E. coli and (20 mm) on Staphylococcus aureus at 1000 ug/disc, while Psidium guajava leaf extract showed inhibition zone of (17 mm) and (15 mm) at 1000 ug/disc on Escherichia coli and Staphylococcus aureus respectively. Similarly the combination (synergy) of the two extracts at 1:1 ratio presented higher activity than the individual extract with inhibition zone of (26 mm) and (22 mm) at 1000 ug/disc against Escherichia coli and Staphylococcus aureus respectively. Thus the results have proved the claim for the use of the two plants in the preparation of concoction for the treatment of gastro-intestinal diseases caused by these pathogens. This study also indicated that Eucalyptus camaldulensis and Psidium guajava leaves could be a good sources of antibacterial agents, however it is recommended that phytochemicals from these plants should be isolated and tested individually in order to find the bioactive compounds.