Synergistic antibacterial activity of Curcumin with antibiotics against Staphylococcus aureus

This study evaluated the synergistic antibacterial activity of curcumin with 8 different antibiotic groups. two reference,one clinical and ten environmental strains of staphylococcus aureus (s. aureus) were tested. disc diffusion assay with 25μg/ml curcumin demonstrated synergism in combination with a majority of tested antibiotics against s. aureus. however,checkerboard micro dilution assay only showed synergism,fractional inhibitory concentration index (fici) <0.5 in three antibiotics i.e. gentamicin,amikacin,and ciprofloxacin. other antibiotics showed indifferent interactions but no antagonism was observed. in time-kill curve,appreciable reduction of bacterial cells was also observed in combination therapy (curcumin + antibiotics) compared to monotherapy (curcumin or antibiotic(s) alone). the antibiotics with higher synergistic interaction with curcumin are arranged in a decreasing order: amikacin > gentamicin > ciprofloxacin.