The study assessed the antibacterial effect of the extracts of Ocimumgratissimum and their combined effect with antibiotic drugs against Salmonella Typhi and Salmonella Paratyphi respectively. The extract of Ocimumgratissimum were prepared using Soxhlet apparatus for ethanol and petroleum ether extract, and hot water percolation for aqueous extracts. The antibacterial activities of the plant extracts, the inhibitory effect to some antibiotic drugs; Ciprofloxacin, Gentamycin, Rifampicin, Erythromycin, Chloramphenicol and Ampiclox as well as their combined effect with the antibiotics were evaluated using the disk diffusion method. The inhibitory zones were recorded in millimeters. Phytochemical analysis of the extract were as well carried using standard procedure. The result of this study showed that the hot water extract showed higher antibacterial activities against S. Typhi and S. Paratyphi respectively, followed by the ethanol extract. The petroleum extract however had the least antibacterial effect at the concentration used. All the antibiotic used had greater inhibitory activities on the test organisms except chloramphenicol that showed partial inhibition against S. Typhi. The result also showed that the combined effect of the plant extracts and antibiotics used showed additive interaction against the test isolates. The result of the phytochemical analysis revealed the presence of some secondary metabolites such as flavonoids, carbohydrates, tannins, alkaloids and steroids and terpenes. The findings of this study therefore validate the antibacterial properties of Ocimumgratissimum and its possession of some active compounds as well as its concomitant use with conventional antibiotics to treat many bacterial infections. It is recommended that the in vivo toxicological activity of the plant be evaluated to determine the real effectiveness and potential toxic effects.
