Synergetic Effect of Green Tea Aqueous and Alcoholic Extracts with Ciprofloxacin Against some Standard bacterial Strains: In vitro study

Abstract

Resistance to commonly-prescribed antibiotics is a global public health problem. Unfortunately resistance has been reported even to newer, potent and expensive antimicrobial agents thus, it necessary to find alternative treatment, such as medicinal plants either alone or in combination with antibiotics due to their fewer reported side effects moreover, their possible affordability and availability. Green Tea (GT) has potential benefits in many aspects most notably in cardiovascular diseases, cancer and obesity. The present study designed to investigate the antimicrobial activity of different concentrations of GT aqueous and alcoholic extracts against standard strains of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923. Moreover, this study provides novel findings about the synergetic activity of GT alcoholic extract and Ciprofloxacin against Staphylococcus aureus ATCC 25923. Two standard antimicrobial susceptibility procedures were used, well diffusion method and broth dilution technique. The clear inhibition zone diameter (IZD) of each extract was measured. The results obtained showed that the GT alcoholic extract had promising antibacterial activity against S. aureus ATCC 25923 only whereas, the two tested strains were resistant to all concentrations of GT aqueous extract. Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) of the GT alcoholic extract against S. aureus ATCC 25923 were 225 mg/ml and 250 mg/ml respectively. Moreover, sub-MIC (200mg/ml) of GT alcoholic extract increased the IZD of Ciprofloxacin against S. aureus ATCC 25923 by 62.5 % which confirmed the synergistic effect. Finally, further studies in the GT with other organic solvents are of paramount importance and highly recommended.