Enhancement effects of antimicrobial activities of β-lactam antibiotics by combination with persimmon tannin against β-lactamase-producing Staphylococcus aureus

Background β-lactamase-producing Staphylococcus aureus is one of the most important bacterial pathogens. Combinations of β-lactam antibiotics with β-lactamase inhibitors such as sulbactam and tazobactam are useful therapeutic methods for combating infections of β-lactamase-producing bacteria. However, bacterial strains which have acquired inhibitor resistance have appeared so new therapeutic agents or new approaches are urgently needed for β-lactamase-producing bacteria. Objective We investigated the antibacterial activity of persimmon tannin derived from the Diospyros kaki cultivar "mishirazu" against β-lactamase-producing S. aureus strains, and the enhancement effects of the antimicrobial activity of β-lactam antibiotics against those strains by combining them with persimmon tannin. The possibility of this combination as a new therapeutic agent against β-lactamase-producing bacteria was examined. Methods The enhancement effects of the antimicrobial activities of β-lactam antibiotics in combination with persimmon tannin were tested by using an MBC (minimum bactericidal concentration) assay. Results The antimicrobial activities of β-lactam antibiotics against β-lactamase-producing S. aureus strains were obviously enhanced by the combination with persimmon tannin. Furthermore, it was clarified that the enhancement effect by persimmon tannin was due to the decomposition control of β-lactam antibiotics by β-lactamase. Conclusion The combined persimmon tannin/β-lactam antibiotic is expected to be a new therapeutic method and/or a new therapeutic agent against infectious diseases caused by microorganisms producing β-lactamase.