Antibacterial activity of curcumin – a natural phenylpropanoid dimer from the rhizomes of <i>Curcuma longa L</i>. and its synergy with antibiotics

Introduction and Objective. Curcumin is a natural substance extracted from turmeric that has broad-spectrum antibacterial properties. The aim of the study was to assess the antibacterial activity of curcumin and its interactions with selected antibiotics against drug-sensitive and multidrug-resistant isolates of emerging bacterial pathogens frequently found in healthcare settings. Materials and method. Antibacterial activity of curcumin was assessed by MIC and MBC values against a total of 30 drug-sensitive and drug-resistant bacterial strains. Curcumin synergy with antibiotics was identified by the checkerboard method.Results. Curcumin has much greater antibacterial activity against Gram (+) bacteria than against Gram (-) organisms. Curcumin showed the best effectiveness against S. aureus, regardless of antibiotic resistance. Since the combination of curcumin with antibacterial drugs inhibited E. coli, E. faecalis and S. aureus, in most cases showing synergistic relationship, the potential use of such combinations can be used to develop an alternative drug in the treatment of selected human pathogens. However, the combination of curcumin with antibiotics did not result in a satisfactory effect in relation to K pneumoniae MBL and KPC strains as well as P. aeruginosa, showing indifferent or antagonistic interactions. Conclusions. As shown by the in vitro data obtained in this study, curcumin has a broad spectrum of antibacterial activity, including emerging and multi-drug-resistant strains. However, the antibacterial effect seems to be bacteria-dependent, and can differ within bacterial species.