Journal Article

Comparison of Diffusion and Spectrophotometric Methods for in Vitro Antibacterial Evaluation of Extract of Ficus capensis Bacteria

Abstract

As part of an ongoing study to provide pharamacological basis for the application of Ficus capensis in Igala traditional medicine for the treatment of several febrile illnesses and infective disorders, the antibacterial activity of the plant extract was investigated at low concentrations using diffusion and spectrophotometric methods. This was aimed at determining the sensitivity of the methods at low concentrations. The millimetre zone of inhibition was determined by agar well diffusion method and the percentage growth inhibition was determined by spectrophotometric assay. The minimum inhibitory concentration (MIC) was determined by broth diffusion method. At 25 μg/ml the percentage growth inhibition of Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus, Acinectobacter baumanii and Burkolderia cepacia, obtained by spectrophotometric method were 69.16%, 67.1%, 70.18%, 70.14%, 69.34% and 67.24% respectively. At the same concentration the diffusion methods indicated that the extract had no antibacterial activity on the test organisms. As the concentration of the extract increased, the diffusion method showed concentration dependent activity on the test organisms. The MIC of the extract for each of the test organisms; E. coli (100 μg/ml), P. aeruginosa (100 μg/ml), K. pneumonia (50 μg/ml), S. aureus (50 μg/ml), A. baumanii (100 μg/ml) and B. cepacia (100 μg/ml) indicated that the extracts inhibited the growth of some organisms at concentrations where zone of inhibition was zero. This suggests that spectrophotometric determination of antibacterial studies is more sensitive than dilution methods, and the broth dilution method is more sensitive than the solid agar well diffusion method

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