Antibacterial and Synergistic Activity of Different Tea Crude Extracts against Antibiotic Resistant S. Aureus, E. Coli and a Clinical Isolate of S. Typhi

Abstract

The antibacterial and synergistic effects of black, green, white tea and other specialty teas such as purple tea extracts processed from Kenyan tea germplasm were evaluated and compared with extracts from processed teas of Chinese and Japanese cultivars using disc diffusion method. Methicillin and penicillinase resistant S. aureus ATCC 25923 was most susceptible to the tea extracts; showing the largest inhibition diameters. Extracts from processed black, black tea buds, green, purple coloured leaf (both aerated and nonaerated) and white teas weakly inhibited (p>0.05) E. coli ATCC 25922 and a clinical isolate of S. typhi at a concentration of 1mg/ml after 24 hours. Synergism was observed between all tea extracts and penicillin G against methicillin and penicillinase resistant S. aureus ATTC 25923. This suggests that the concomitant administration of tea and penicillin G may not impair the antibacterial activity of penicillin G.