In-vitro antimicrobial and synergistic properties of water soluble green and black tea extracts

Abstract

Green and black teas extracts are known for their antibacterial activity against many pathogenic microorganisms. These studies have been necessitated by the need to combat the recent rise of drug- resistant human pathogens which is becoming a common occurrence in the world making easily manageable infections to become life threaten ing illnesses. This study evaluated the antimicrobial activity of water soluble green and black tea extracts from a high quality Kenyan tea clone TRFK 6/8 against antibiotic resistant Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 using agar well diffusion method. Green and black tea ext racts effectively inhibited the growth of both E. coli ATCC 25922 and S. aureus ATCC 25923 at concentrations of 0.1 and 0.05 mg/ml, respectively after 24 h. Green tea extracts and ge ntamicin showed greater zone of inhi bition compared to penicillin G. In addition, the possible synergistic activity of water soluble green tea extract and antibiotics was also determined using agar well diffusion method. A co mbination of penicillin G and green tea extract inhibited the growth of E. coli ATCC 25922 and S. aureus ATCC 25923 compared to penicillin G alone while gentamicin exhibited an additive and antagonist ic effect depending on tested bacteria. Green and black tea extracts can be used as an antimicrobial agent and also green tea extract can be used in combination with penicillin G to manage resistan t pathogenic bacteria. Fur thermore, tea which is a proven safe, cheap and readily available compound can be used in more ambitious trials to test the antimicrobial efficacy and chemo-preventive effects in animal and human models.