ANTIBACTERIAL ACTIVITY OF GREEN TEA EXTRACT IN COMBINATION WITH CEFOTAXIME ON DIARRHEA CAUSING ESBL PRODUCING E. COLI

摘要

Objective: Owing to the continuous evolution of antibiotic resistance, treatment with natural products represents significant adjuncts or alternatives to conventional antibiotic therapy. Enterobacteriaceae especially Escherichia coli have acquired antibiotic resistance due to production of Extended spectrum Beta-lactamases (ESBL). Methods: Effect of Aqueous extract of Green tea (AGTE) was studied on 44 ESBL producing, diarrhea causing E. coli . ESBL production of the strains was confirmed by phenotypic confirmatory disc diffusion test (PCDDT) and E-test. Antibacterial activity of AGTE was studied by disc diffusion method and the Minimum Inhibitory Concentration (MIC) of AGTE and Cefotaxime were determined by an agar dilution technique. The combined activity of AGTE and Cefotaxime was determined by calculating the fractional inhibitory concentration (FIC index) by the checkerboard method. The active ingredients epicatechin (EC), epicatechin-3-gallate (ECG), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG) present in the extract were quantitated by High Performance liquid Chromatography (HPLC). Results : AGTE exhibited significant antibacterial activity as the observed zones of inhibition ranged from 10–26 mm against the 44 ESBL producing E. coli strains. The MIC of AGTE was found to be in the range of 2.5-20 mg/ml with a mean of 7.23 mg/ml. 8 test strains showed synergism whereas the remaining showed an additive effect between AGTE and Cefotaxime. By HPLC analysis the concentration of EC, ECG, EGC, EGCG were found to be 7.03, 10.08, 9.99 and 43.57 respectively, expressed as percentage w/w. Conclusion: As green tea extract has shown substantial antibacterial as well as synergistic activity, it can be of potential therapeutic value against ESBL producing Escherichia coli gastrointestinal infections. Keywords: ESBL, Green tea, EGCG, Synergy.