Comparison of the Antimicrobial Efficacy of Green and Black Tea Extracts Against E.Coli: In Vitro and In Vivo Study -

Abstract

Green and black tea is one of the most popular beverages consumed worldwide. Moreover, during the last two decades it has received much attention in regard to its beneficial effects on various human health problems .This study aimed to investigate the antibacterial effect of hot and cold extracts of green tea and black tea separately against E. coli and after infecting the burned skin rat with them, also to screen the effect of both types of tea on rat liver and kidney. Sixteen male rats divided into four Groups (4 animals each), Group 1: untreated rat (control). Group 2: burn rats infected with E.coli(1.5×108 bacteria /ml). Group 3: burn treated by Green tea aqueous extract (1000 µg/ml) for E.coli bacteria. Group 4: burn treated by black tea extract (800 µg/ml) for E.coli bacteria. The tea extracts antimicrobial activity was analyzed by agar diffusion inhibition assay and minimum inhibitory concentration. Results exhibited that E. coli in particular, have high levels of resistance against 13 antimicrobial and response only to Imepeneme and Meropenem . Hot watery green tea extract is more effective against bacterial type than cold once. Based on assessment of inhibition zones. E. coli was more sensitive black tea extraction, according to the inhibitions zone. Depending on MIC, we concluded that hot extract from two types of teas have the best antibacterial effect than cold extract demonstrated that the best MIC against E.coli is hot green tea extract (400 µg/ml) then hot black tea extract (600 µg/ml) followed by cold green tea extract (800 µg/ml) and less activity is cold black tea extract (1000 µg/ml). Infected rats showed inflammation and hemorrhage. While treating rats with tea extracts dermally approximately restored kidney normal histological architecture and liver became nearly normal in histological structure. Black tea extract showed greater effectiveness in tissue recovery than green once.