Fractional inhibitory concentration index of poly-herbal combination of Morinda lucida and Pterocarpus santalinoides Methanol root extracts against multiple drug resistant bacterial isolated from diabetic foot ulcers.

Abstract

The antimicrobial resistant bacteria make treatment of microbial infections with common antibiotics difficult and expensive. This has led to a serious scientific search for combination therapy antimicrobial agents that will be safe, effective, less toxic, and affordable. The aim of this study was to evaluate the in-vitro action of combining the methanol root extracts of Morinda lucida and Pterocarpus santalinoides against multiple drug-resistant organisms isolated from diabetic foot ulcers. The phytochemical constituents were determined using standard methods. The antimicrobial susceptibility profile and antibacterial activity of the extracts was tested using agar well diffusion test. The minimum inhibitory concentration and fractional inhibitory concentration were done using Checker-board micro-titration method, and the fractional inhibitory concentration index (FICI) calculated, and time-kill assay was done to confirm the synergistic and bactericidal activity. The antimicrobial testing of the combination showed high zones of inhibition diameter ranging between 29-40mm against the isolates. The FICI of the methanol roots extract combination demonstrated synergy against the test isolates ranging between 0.12-0.19. The time of kill showed a huge decrease in the quantity of viable cells. This study suggests that this plant combination could serve as an alternative antimicrobial agent to treat multiple drug-resistant organisms.