The in vitro study was compared the antibacterial activity of green tea and
black tea extracts against methicillin resistant Staphylococcus aureus (MRSA). Green
tea extract was found to have higher antimicrobial activity on MRSA with an
inhibition zone of 20 mm at a concentration of 10 gm/100 ml. For black tea extract,
the inhibition zone was 15 mm at same concentration .The minimum inhibitory
concentrations for the green tea and black tea were 4mg/ml and 8mg/ml respectively.
The in vivo study of the antimicrobial effect of both green and black tea was
investigated, by subcutaneous inoculation of four rabbits with MRSA bacteria. After
that immediately treated with a series dilution of tested material (green and black tea),
the development of swelling and the degree of necrosis were scored. The green tea
showed marked reduction in the size of swelling less than 2mm at the concentration of
10mg/ ml; also there is a marked reduction in the severity of necrosis. For black tea a
marked reduction occur in the size of swelling (6-10mm) at the concentration of
10mg/100ml; also there is a marked reduction in the severity of necrosis at the same
concentration. This study concludes that green and black tea extracts were showed to
have an antibacterial activity against MRSA and a therapeutic effect against skin
infection caused by MRSA in rabbits