Abstract
The antibacterial activities of Hibiscus sabdariffa and Quercus infectoria extracts were screend against 5 spicies of Gram negative bacteria, Pseudomonas aeruginosa, Escherichia coli, Serratia marcescens, Proteus vulgaris and Klebsiella pneumonia. Calyces of Hibiscus sabdariffa and nutgalls of Quercus infectoria were extracted in acetone using a soxhlet apparatus. Extracts of the plants showed high antibacterial activities on all types of bacteria tested using the disc diffusion method and comparing with the standard antibiotics Gentamicin and cephalexin . The combined effect of the two extracts was also studied against the tester bacteria, and found increase the inhibition zone diameters at all concentrations, except in S. marcescens which was inhibited at concentrations from 200-6.25 mg/ml and Pr.vulgaris which appeared more sensitive against the combination between the two extracts. The calculated inhibition zone reached 25 mm using the concentration 200 mg/ml which is greater than the control effects. The study also determined the Minimum Inhibitiory Concentration MIC of the two extracts and the combination between them. The bacteria also showed high sensitivity against the extract combination,with Pr. vulgaris was also more sensitive than other bacteria. The calculated MIC reached 0.0625 mg/ml meanwhile. K. pneumonia appeared less sensitivity, the calculated MIC was 0.125 mg/ml.
