Adenium obesum plant (stem-bark) was collected, identified, air-dried, ground and extracted using hot-continuous extraction method. Standard phytochemical tests and antimicrobial tests using Kirby and Bauer techniques were adopted for the phytochemical screening and antimicrobial tests of the plant stem-bark methanolic extract respectively. The MIC of methanolic extract in combination with oxytetracycline using 8 different clinical bacterial isolates, both Gram positive and Gram negative, was found to be around (62.5 μg/ml to 1250 μg/ml).In all, 87.5% showed synergistic activity against 8 different bacterial isolates, both gram positive and gram negative species. The highest synergistic activity was attained against Streptococcus pyogenes. Phytochemical examination of the extract revealed the presence of alkaloids, steroids, saponins, glycosides, anthraquinones, tannins and flavonoids. This result indicated strong antibacterial activity of the methanolic extract in combination with oxytetracycline against the pathogenic bacterial isolates.
Keywords: synergism, methanol, Adenium obesum, oxytetracycline, extract, clinical isolates