Antibacterial activity of the leaf extracts of Psidium guajava (guava) on selected microorganisms

Methanol and aqueous extracts of the leaves of Psidium guajava were tested for the presence of antimicrobial activity against Escherichia coli, Staphylococcus aureus, Salmonella typhi and Streptococcus pyogenes. Three concentrations of the leaf extract were tested namely 50 %, 33 %, and 25 %. All of the leaf extracts showed antimicrobial properties on all of the test organisms. Methanol and aqueous extracts of the higher concentrations produced bigger zones of inhibition than the extracts of lower concentration which were significantly different (0.01 level, F-test). Duncan\u27s Multiple Range test however showed that the 33 % and the 50 % concentration of both extracts were not significantly different from each other. The 33 % and 50 % methanol extracts also produced bigger zones of inhibition than the 33 % and 50 % water extracts respectively for all test organisms and these were significantly different (0.01 level, F-test)