The Synergistic Potentials of Platostoma africanum and Psidium guajavaagainst Some Multi-drug Resistant Bacteria

Abstract

Assessment of synergism of the plant combinations against the test isolates was done by the checkerboard method. Their fractional inhibitory concentrations (FICs) indices were calculated and used to indicate synergism against the test organisms. Results: P. guajavashowed broad antibacterial activity against both groups of resistant organisms. P. africanumshowed poor antimicrobial activity against the Gram-negative organisms compared to the Gram-positive strains. Determination of bactericidal activity of the extracts on the test isolates showed that the killing ability of the plants was time dependent. Most combination ratios of the plant extracts showed synergism against ESBL-producing E. colistrains and additivity against MRSA. The 8:2 (P. guajava: P. africanum) combination showed synergism against all the test isolates, with FIC indices ranging from 0.106 to 0.825. Conclusions: P. guajavaand P. africanum(8:2) combination has synergistic and broad spectrum antibacterial activity against ESBL-producing Escherichia coliand MRSA. The possibility of using the combination for disinfection is foreseeable. Characterization of the active principles from these plants is needed.