P17 Identification of a novel synergistic combination of natural extracts for infection control in diabetic ulcers

Abstract

By 2030, 550 million people will have diabetes, of which 25% will go on to develop diabetic leg and foot ulcers. Characterised by persistent, polymicrobial infections and antibiotic resistance, the development of new antimicrobials for the treatment of diabetic ulcers is a research area of critical importance. In this study, we examined the antibacterial activity of extracts from two natural products, garlic and sandalwood, tested against a panel of five Gram-positive and Gram-negative diabetic ulcer-associated bacteria. Synergistic combinations of antimicrobials are often used as a method of combating multi-drug resistant infections due to the ability of the individual antimicrobials to exhibit different mechanisms of actions against bacteria. Here we tested the synergistic relationship of garlic and sandalwood extracts using a checkerboard titration method and subsequently completed an assessment for synergy using the fractional inhibitory concentration index (FICI). In vitro, we were able to demonstrate that the selected natural extracts successfully inhibited S. aureus, MRSA, P. aeruginosa, E. faecalis and A. baumannii – a prolific multi-drug resistant bacteria. Furthermore, a synergistic relationship between the two antimicrobials was demonstrated when tested in combination against four of the five bacteria. This includes S. aureus, which has been reported to infect up to 93.5% of diabetic ulcers. These results provide us with novel information on the synergistic antimicrobial relationship of extracts from two well-known natural products – garlic and sandalwood. Additionally, the broad-spectrum antibacterial activity exhibited by the combination of natural extracts presents a great opportunity in the future treatment of diabetic ulcers.