RESUMO
Information on the potency of many African medical plants against microorganisms is scanty, and in the current wave of antimicrobial resistance against chemotherapeutic drugs, there is need to search for plants that could be resistance-free and affordable. The objective of this study was to investigate the antimicrobial effects of the extracts of Lasianthera africana (E1) and Heinsia crinata (E2) in combination with chloramphenicol, on Escherichia coli, Salmonella typhi, Staphlococcus aureus and Candida albicans. For this purpose, the dilution sensitivity and disc diffusion techniques were respectively applied in determining minimum inhibitory concentration (MIC) of the plant extracts, and the sensitivities of the organisms to the plant extracts and their combinations with chloramphenicol. L. africana and H. crinata showed very high antimicrobial activity against all the test organisms. In combination, the effect of E1 on E. coli and S. typhi was completely antagonized by that of E2, whereas additive effect on S. aureus and C. albicans was observed, indicating that the combination of E1 and E2 might be effective against gram positive pathogenic organisms. The combination of either plant extract with chloramphenicol produced synergistic effect on only C. albicans. The smaller MIC of E2 indicated greater effectivity than E1. It is concluded that the additive effect produced by the combination of the two plant extracts, and the synergic effect from the combination of any of the extracts with chloramphenicol, offer alternative therapy to gram positive bacterial infections and candidiasis respectively.