Synergistic antibacterial effect of stem bark extracts of <i>Faidherbia albida</i> and <i>Psidium guajava</i> against methicillin resistant <i>Staphylococcus aureus</i>

Abstract

The study was aimed at screening the stem bark extracts of Faidherbia albida and Psidium guajava for synergistic antibacterial effect against methicillin resistant Staphylococcus aureus (MRSA). The powdered plant materials were extracted with methanol using cold maceration technique and the extracts were screened for alkaloids, flavonoids, tannins, saponins, and steroids using standard methods. The test organism was isolated from subjects with boils in Gombe State and confirmed using Gram staining and standard biochemical procedures as well as cefoxitin susceptibility test. Confirmed MRSA were subjected to susceptibility test of the plant extracts using agar well diffusion and broth dilution techniques. The results of the study showed percentage extraction yields of 15.7% and 7.5% for F. albida and P. guajava stem barks respectively. Sensitivity test of MRSA isolates to the extracts using agar well diffusion method revealed zone diameters of 8-10mm while combination of extracts showed activity of 21mm .The minimum inhibitory concentration (MIC) of the extracts combination was found to be 0.25mg/ml while the minimum bactericidal concentration (MBC) was determined to be 0.5mg/ml. The study revealed that stem bark methanol extracts combination of the two plants possess synergistic antibacterial activity against MRSA and so can be exploited as a viable option in production of safer plant-based drugs against the bacterium. Keywords: Synergistic, Faidherbia albida , Psidium guajava , Methicillin Resistant, Staphylococcus aureus