Inhibitory and killing activities of black tea (Camellia sinensis) extract against Salmonella enterica serovar Typhi and Vibrio cholerae O1 biotype El Tor serotype Ogawa isolates

Introduction and objective: Previous studies have shown the potential antibacterial activity of black tea, Camellia sinensis, extract against many pathogenic bacteria including Gram-positives (Listeria monocytogenes and Staphylococcus aureus) and Gram-negatives (Vibrio cholerae and Salmonella enterica serovar Typhi). The aim of the current study was to assess the in vitro antibacterial activity of C. sinensis ethanolic extract (CAS) against multidrug-resistant (MDR) clinical isolates of S. Typhi and V. cholerae O1 biotype El Tor serotype Ogawa (V. cholerae Ogawa ). 

Materials and methods: The zone diameter of inhibition (ZDI) and minimum inhibitory concentration (MIC) values of CAS for S. Typhi and V. cholerae Ogawa isolates were determined by agar diffusion and agar dilution techniques. Bacterial killing studies were carried out in order to assess the bactericidal activity of CAS against S. Typhi and V. cholerae Ogawa, from Kolkata, India.

Results: For the S. Typhi and V. cholerae Ogawa isolates, the ZDIs of CAS ranged 12-17mm and 13-21mm, respectively, and the MICs of the extract were 400-600µg/ml and 200-600µg/ml, respectively. The CAS had bactericidal action at concentrations 512µg/ml and 256µg/ml, respectively for S. Typhi and V. cholerae Ogawa.

Conclusion: The black tea (C. sinensis) extract could be useful in combating emerging drug-resistance among enteropathogens including S. Typhi and V. cholerae Ogawa.