In Vitro Evaluation of the Antimicrobial Synergy of Curcuma longa and Allium sativum Extracts Against Gram-Positive and Gram-Negative Clinical Bacterial Isolates

Interest in antibacterial products from plants is revived by the ongoing increase of drug-resistant bacteria by bacteria that do not respond to antibiotics. This research looked at individual and combined doses of garlic and turmeric for their antibacterial properties to resistant bacterial strains. This trial involved numerous variables, including extraction yields, totalu47368 phenolics, total flavanoids, and a qualitative phytochemical profile, both ethyl and water extracts were analyzed for their antibacterial activity using an agar diffusion assay. In addition, minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were obtained through microdilution methods according to guidelines provided by the Clinical and Laboratory Standard Institute (CLSI). The interaction between the two ethyl extracts was evaluated using the checkerboard method and determined FICI was used to determine which extract worked best together. In all cases, the three trials were replicated and reported as mean ± standard deviation with differences measured using ANOVA and Tukey’s test (p< 0.05). Finally, both ethyl extracts of Gill and turmeric produced the lowest (~6.25 mg/mL) MIC for S. aureus as compared to both (~25 mg/mL) for E. coli. The turmeric/garlic combination was found to be synergistic against both S. aureus and K. pneumoniae (FICI = 0.38) but did not exert an effect on E. coli because the inhibition achieved was due to the garlic alone. These data suggest that both garlic and turmeric should be considered for their antibacterial properties, but that the turmeric/garlic combination has been shown to produce a genuine and quantifiable synergy against 2 different Gram-positive organisms and the Gram-negative organism Klebsiella and that there was no synergy against E. coli.