Journal of Antimicrobial Agents

In vitro Antimicrobial Activities of Vigna subterranea

Abstract

Ajiboye AA, Oyejobi GK

The antibacterial assay of the seed of Vigna subterranea (Bambara Groundnut) on certain clinical isolates: Proteus mirabilis, Escherichia coli, Klebsiella aerogenes, Klebsiella ozaenae, Staphylococcus aureus and Pseudomonas aeruginosa was determined using the agar diffusion technique to investigate its potential use as antibacterial agent. The antimicrobial activity of the test organisms to the seed extract was screened by using the agar-well diffusion method. An inoculum suspension was swabbed uniformly to solidified 20 ml Mueller-Hinton Agar (MHA) and the inoculum was allowed to dry for 5 minutes. Holes of 5 mm in diameter were made in the seeded agar using sterile cork-borer. Aliquot of 50 μl from each seed extract was added into each well on the seeded medium and allowed to stand on the bench for 1 hour for proper diffusion and thereafter incubated at 37°C for 24 hour. The resulting inhibition zones were measured in millimeters (mm). Negative controls using 50 μl PBS were also run in the same manner and parallel to the treatments. These studies were performed in duplicate. The seed extracts of V. subterranea showed varying antimicrobial activities against the test organisms. Antimicrobial screening indicated that V. subterranea showed the highest (39 ± 2.55 mm) inhibition against E. coli and K. ozanae at dilutions 1 and 2 respectively. The least activity was observed at dilutions 2 while P. mirabilis and E. coli both had zones of inhibition of 8 ± 0.00 mm and 8 ± 1.41 mm respectively. Susceptibility testing using standard antibiotics (positive control) was also carried out. P. mirabilis, E. coli and K. aerogenes were susceptible to the entire tested antibiotics except Augumentin (AUG) and Amoxicillin (AMX). The diameters of the clear zones of inhibitions were measured and the result recorded to the nearest millimeters (mm). The diameter of the zone was used as a measure of the susceptibility of the isolate and the diffusion rate of the seed extracts/antibiotics through the agar medium. The result of the study suggests that seed extract of V. subterranea can be used for the treatment of infections caused by the test organisms.