Antibacterial study of guava leaves on some enteric bacteria (E. coli and Shigella dysentriae) from Sokoto, Nigeria

Yusuf Sarkingobir, Abdulrahman Hamza, Malami Dikko, Marwanu Abubakar, Asiya Giddado Yabo, Balkisu Isa Muhammad
Corresponding email: [email protected]


This study conducted identification of phytochemicals in guava and expunge the antimicrobial capacity possessed by the plant on some bacteria. Ethanol and water were utilized to make the plant extracts that are used against Escherichia coli, and Shigella dysenteriae all isolated from clinical isolates. The results showed that the phytochemicals were present in leave extracts of P. guajava. The plant contains alkaloid, saponins, flavonoids, tannins, steroid. The antibacterial activity of aqueous and ethanolic leaves extract of P. guajava revealed the mean diameter of zone of inhibition of extract on the test isolate with E. coli spp being the most susceptible isolate at 200 mg/ml concentration (20 mm). The ethanol extracts revealed the highest activity against the test bacteria, Escherichia coli (20mm zone of inhibition, MIC of 12.5mg/ml, and MBC of 25mg/ml) followed by Shigella (18.3mm zone of inhibition, MIC of 6.25mg/ml and MBC of 25mg/ml). The aqueous extracts showed slightly lower activity on the test organisms compare to the water extracts. Escherichia coli (8.6mm zone of inhibition, MIC of 12.5mg/ml and MBC of 12.5mg/ml), followed by Shigella (5mm zone of inhibition, MIC of 12.5mg/ml and MBC of 25mg/ml). The obtained result displayed that both extracts impede the growth of the test isolates using 6.25 – 25mg/ml concentration. In turn, the leave contains of the plant can be improved to benefit from its antibacterial and phytochemical compounds.

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