Catechin gallate a promising resistance modifying candidate to potentiate β-lactam antibiotics to overcome resistance in Staphylococcus aureus

Drug discovery is a cost intensive and time consuming approach therefore contingent alternatives are being explored to combat drug resistant bacteria which cause chronic infections. Resistance modifying agents offer plausible alternatives in reviving the current antimicrobial drugs thereby making them effective to be used in clinical settings. We for the first time report the promising activity of (−)-Catechin gallate selected using in silico studies with FemA protein of Staphylococcus aureus. The MIC of the test isolates of S. aureus viz. NCTC 6571, MTCC737 and MTCC 96 by visual method was 500 μg and 8000 μg for Oxacillin and Penicillin respectively. (−)-Catechin gallate induced an 8-fold reduction in the MIC of Oxacillin in S. aureus NCTC 6571 and MTCC 737 at concentration of 7.8 μg/ml and 31.25 μg/ml respectively. A 4-fold reduction, in MIC of Penicillin and Oxacillin at concentration of 7.8 μg/ml of (−)-Catechin gallate in NCTC 6571 and MTCC 96 respectively. These synergistic combinations in time kill assay exhibited a reduction between 2 and 6 log10 in the CFU of the test microbes thereby suggesting (−)-Catechin gallate to be a promising candidate for further evaluation as a resistance modifying agent to overcome resistance to first generation of β-lactam antibiotics.