In vitro antibacterial activity of green tea (Camellia sinensis) extract against staphylococcus aureus and MRSA

Context: There is a worldwide emergence of multi drug resistant bacteria. Recently no new antibiotics have been approved for use, although some are in the pipeline, undergoing phase 2 or 3 clinical trials. There is need for alternate compounds for treatment; one such agent is green tea. Green tea has antimicrobial effects against a variety of Gram positive and Gram negative bacteria (e.g., Staphylococcus aureus, Enterococcus sp, Escherichia coli, Salmonella sp.) Aims: To determine the antibacterial activity of green tea extract against Methicillin resistant and sensitive Staphylococcus aureus (MRSA &MSSA) Settings and Design: Department of Microbiology, Cross sectional study Materials and Methods: A total of 15 consecutive laboratory isolates of S. aureus (MSSA) and MRSA each, isolated between August to September 2017 were inoculated in media containing Green tea extract [epigallocatechin gallate (EGCG)] in concentrations of 2.5mg/ml, 5mg/ml, 10mg/ml. After overnight incubation the bacterial broth was subcultured using standard calibrated loop (0.01ml) onto Mueller Hinton agar. The lowest concentration of EGCG in which no growth occurred was considered as the minimum bactericidal concentration (MBC). Results: EGCG had antimicrobial activity against S. aureus ATCC-25923, P. aeruginosa ATCC-27853, K.pneumoniae ATCC-BAA 1705 and E.coli ATCC-25922- MBC 99.9% was 5mg/ml. But for E.faecalis ATCC 29212 MBC 99.9% was 10mg/ml. EGCG was effective against clinical isolates of MSSA and MRSA with MBC of 5mg/ml except 2 MRSA isolates for which MBC was 10mg/ml. Conclusions: Green tea extract- EGCG has antibacterial activity not only against standard bacterial strains but also against clinical isolates of S.aureus and MRSA.