Antimicrobial Evaluation of Extracts and Fractions of Daniella oliveri Leaf on Selected Clinical Enteropathogens

Abstract

Background: Diarrhoea is one of the major health threats to the populace in the tropics, and also one of the killer diseases in children under 5 years of age. Antimicrobial resistance and its spread pose serious public health threats, hence the need for development of safer and more effective antibacterial agents. Daniella oliveri Hutch and Dalz is used in ethnomedicine for the treatment of diarrhoea and other gastrointestinal disturbances.

Objective: To investigate the antimicrobial activity of Daniella oliveri leaves on diarrhoeal pathogens.

Methods: Successive plant extraction was carried out with hexane, ethylacetate and methanol using soxhlet apparatus. Methanol extract was fractionated using vacuum liquid chromatography (VLC). Phytochemical screening was done using standard chemical assays. Antibiogram of test isolates was carried out using disc diffusion assay. Antimicrobial activity of plant extract and fractions against strains of diarrhoeagenic Escherichia coli, Salmonella cholerae-suis, Shigella dysenteriae, Proteus mirabilis and Acinetobacter baumannii was determined by agar well diffusion and MIC by agar dilution methods. Kill-kinetics study was carried out using viable count technique.

Results: Terpenoids, steroids and anthraquinones were detected in fractions of D. oliveri. Antibiogram assay showed that 66% of isolates were MDR. Extract and fractions produced appreciable zones of inhibition on all challenge organisms except Acinetobacter baumannii. MICs ranged between 6.25-25 mg/ml. Kill kinetics studies showed total kill on susceptible pathogens after 24 hours.

Conclusion: This research has shown D. oliveri is a promising drug candidate for the management and treatment of diarrhoea.