A unique combination of Alchornea cordifolia and Pterocarpus santalinoides in the management of multi-drug resistant diarrhoegenic bacterial infection.

Background: Traditionally, diarrhoea in our locality has often been managed using herbs. Multi-drugresistant organisms refer tomicrobes that areresistant to the effects of antimicrobial drugs to which they were previously susceptible at therapeutic range. Objectives: This study investigates the combined effects of Alchornea cordifolia and Pterocarpus santalinoides leaves extracts against selected multi-drug resistant diarrhoegenic bacteria. Methods: Fresh plant seeds were collected from the plants, shade-dried, pulverized and extracted with methanol in a Soxhlet apparatus. Antibacterial activities of these plants were investigated using agarwell diffusion assay. The MIC and FIC of the extracts against test isolates were determined using agar well diffusion method and checkerboard assay respectively. The bactericidal effects of the extracts against the isolates were evaluated using Time-Kill Assay. Results: MIC values of methanolic extracts against drug resistant strains of Salmonella typhi , Shigella dysenteriae , Escherichia coli and Staphylococcus aureusranges from 6.25 µg/mL to 12.5 µg/mL. The combination of Alchornea cordifolia and Pterocarpus santalinoides extracts showed synergy at 8:2 and 4:6 combinations against S. aureus, Salmonella typhi and E. coli; at 7:3 combinations against E. coli ; at 6:4 and 3:7 combinations against S. aureus, Salmonella typhi , S. dysenteriae ; at 5:5 combinations against all the test isolates; at 2:8 combinations against S. aureus , S. dysenteriae and E. coli but additive against Salmonella organisms; at 1:9 combinations against S. aureus and Salmonella organism. Conclusion: The methanol extracts of the plants at combinations 5:5 is synergistic against all the tested multi-drug resistant diarrhoegenic bacteria. Combination of Salmonellaand A. cordifolia showed potentials of synergism against the test isolates. The detection of synergy suggests presence of antibiotic resistance modifying compounds in those extracts.