Effect of Interaction of Methanol Leaf Extract of Spondias mombin (Linn) and Amoxicillin on Some Diarrheagenic Escherichia coli
Purpose: To study the effect of interaction between methanol leaf extract of Spondias mombin and amoxicillin on diarrheagenic Escherichia coli (DEC).
Methods: Cold methanol extraction of Spondias mombin leaf and its phytochemical screening were carried out. Isolated, characterized and identified strains of enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), and enterohemorrhagic E. coli (EHEC) from watery stool, mucoid bloody stool and watery bloody stool of diarrheal patients, respectively, were confirmed and typed by conventional and molecular methods. The minimum inhibitory concentration (MIC) and ½ MIC at which the extract and amoxicillin interacted were determined.
Results: Spondias mombin extract showed remarkable antibacterial activity at extract concentration of 50 - 200 mg/mL with a mean zone of inhibition (MZ) ≥ 11.1 and activity index (AI) of 0.8 - 1.1. MIC of 12.5 mg/mL was observed for both ETEC and EIEC while it was 6.25 mg/mL for EHEC. The extract showed synergistic interaction at various concentrations (50 – 200, 12.5 and 6.25 mg/mL, respectively) with amoxycillin against ETEC, EHEC and EIEC. Synergy across a wide range of concentrations compared favourably with the ½ MIC and MIC of both extract and amoxycillin for ETEC. The extract contained moderate levels of alkaloids, flavonoids and tannins, as well as a lot of saponins, and low levels of phenol. The activity of the extract of Spondias mombin compares well with that of amoxicillin with AI ≥ 1 in some cases.
Conclusion: A synergistic interaction between the leaf extract of S. mombin and amoxicillin confirms the extract as potential antibacterial agent but further studies are required to ascertain this.
Keywords: Diarrheagenic E. coli, Drug interaction, Spondias mombin, Amoxicillin, Time-kill, Activity index
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