In vitro antibacterial activity of selected medicinal plant extracts against Escherichia coli in Adami Tulu Jiddo Kombolcha district, Ethiopia.

BACKGROUND

The increasing prevalence of antimicrobial-resistant Escherichia coli necessitates the exploration of alternative antimicrobial agents from botanical sources.

OBJECTIVE

This study evaluated the in vitro antibacterial activity of methanolic and ethanolic leaf extracts of Datura stramonium, Balanites aegyptiaca, and Acokanthera schimperi against field and reference strains of E. coli.

METHODS

Following phytochemical screening, antibacterial activity was determined using the disk diffusion method, while Minimum Inhibitory Concentrations (MIC) and Minimum Bactericidal Concentrations (MBC) were determined using the broth dilution method.

RESULTS

All extracts demonstrated concentration-dependent inhibitory effects. The methanolic extract of D. stramonium (100 mg/mL) exhibited the highest antibacterial activity, producing a zone of inhibition of 20.27 ± 0.37 mm against the field isolate. This inhibition zone was similar to that of the ciprofloxacin positive control (19.7 ± 0.3 mm). Methanol consistently demonstrated higher extraction yield and antibacterial activity than ethanol across most tested species. D. stramonium and A. schimperi showed MIC values as low as 0.78 mg/mL, while all extracts exhibited bactericidal activity based on an MBC/MIC ratio of 2.

CONCLUSION

These findings support the potential of the selected medicinal plants as sources of antibacterial compounds and provide a basis for further investigations involving bioactive compound characterization, safety assessment, and in vivo validation.