The synergistic effect of turmeric aqueous extract and chitosan against multiple drug-resistant bacteria

Abstract In this study, we aimed to investigate the antibacterial and anti-biofilm effects of turmeric and chitosan against the planktonic and biofilm forms of the multiple drug-resistant (MDR) bacteria. A group of MDR bacteria, including clinical isolates of methicillin-resistant Staphylococcus aureus, carbapenem-resistant Pseudomonas, carbapenem-resistant Enterobacteriaceae, and AmpC-producing Enterobacteriaceae were collected by phenotypic and genotypic assays. The broth micro-dilution method was used to investigate the minimum inhibitory concentration of turmeric aqueous extract and chitosan. To investigate the synergistic effect of the combination of these natural compounds, we used the checkerboard assay. According to the results of this study, turmeric and chitosan showed inhibitory effects on MDR bacteria, especially on the planktonic form of MRSA as a Gram-positive compared with tested Gram-negative bacteria (carbapenem-resistant Pseudomonas, carbapenem-resistant Enterobacteriaceae, and AmpC-producing Enterobacteriaceae). The antibiofilm effect of turmeric and chitosan were more found in carbapenem-resistant Pseudomonas isolates. There was no significant difference between the tested Gram-negative bacteria because most of the tested strains were inhibited in 512 μg/mL and 1024 μg/mL concentrations of chitosan and turmeric aqueous extract. In this study, turmeric aqueous extract and chitosan show significant antibacterial and anti-biofilm properties. However, the effect of these compounds (the turmeric and chitosan) should investigate in vivo or animal models for use in pharmaceutical and disinfectant formulations.