Abstract

Pisidium guajava and Gongronema latifolium are local plants used traditionally in south-eastern Nigeria to treat ailments such as cough, loss of appetite, malaria and stomach disorders. In this study, aqueous and ethanolic leaf extracts of P. guajava and G. latifolium were screened for antibacterial activity against two clinically isolated organisms of the gastrointestinal tract, Escherichia coli andStaphylococcus aureus. Results obtained show that leaf extracts of both plants possess significant antibacterial activities against the two isolates. Ethanolic extracts showed more inhibitory effect compared to the aqueous extracts. Extracts of P. guajava exhibited higher inhibitory effect than that of G. latifolium. The diameter of zones of inhibition by the leaf extracts of P. guajava was 8 - 16 mm and 14 - 21 mm respectively for the aqueous and ethanolic extracts. The minimum inhibitory concentrations (MICs) were 5.0 and 0.625 mg ml^-1respectively for the aqueous and ethanolic extracts of P. guajava. For the extracts of G. latifolium, the diameter of zones of inhibition was between 6 and 10 mm while MICs were 10.0 and 2.5 mg ml^-1 respectively for the aqueous and ethanolic extracts.

Key words: Pisidium guajava, Gongronema latifolium, antibacterial activity, minimum inhibitory concentration (MIC), Escherichia coli, Staphylococcus aureus.