<i>M. indica and</i> <i>B. dalzeilii </i>are common medicinal plants grown naturally in most parts of tropical and subtropical regions of Northern Nigeria. They are used traditionally in the treatment of diarrhea in children especially at teething age. This study was conducted to detect, isolate and identify E. coli O157:H<sub>7</sub> from diarrheal stools of children and evaluate antibacterial activities of M<i>. indica</i> and <i>B. dalzielii </i>extracts against the test bacteria. Total number of one hundred (100) samples were collected from Children Clinic of General Hospital Gusau, Zamfara State Nigeria using standard microbiological procedure. <i>E. coli</i> O157:H<sub>7</sub> is an important pathogens of human, implicated as one of the important causative agents of diarrhea in children especially at teething ages. The test organism was detected, isolated and identified using Cultural Growth Characteristics, Gram reactions, Serology, Biochemical tests and Molecular screenings. The sample plants extracts were obtained using Soxhlex Apparatus with Methanol as solvent. Phytochemical screening of the plants extracts revealed the presence of Alkaloids, Flavoids, Tannins and Saponnins. Antibacterial activities of the aqueous methanolic extracts of the test plants against <i>E. coli</i> O157:H<sub>7</sub> was evaluated using Sensitivity Tests, Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal concentration (MBC). The most active phytochemical compounds was obtained by fractionation using Chromatography. Chemical structure of the most active phytochemical was elucidated using Nuclear Magnetic Resonance Spectroscopy. Confirmation of antibacterial activities of the test plants, lend credence to the traditional used of those plants in the treatment of diarrhea in children especially at teething ages. It is therefore recommended that, <i>M. indica </i>and <i>B. dalzeilii</i> can be further purified to yield templates for synthesis of Orthodox drugs for the treatment of diarrhea in children.