Evaluation of the Antimicrobial Activity of Some Medicinal Plants against Enteric Bacteria with Particular Reference to Multi-Drug Resistant Vibrio cholerae

Purpose: To evaluate the anti-enterobacterial potential of nine ethnobotanically selected plants traditionally used in different parts of India for the treatment of gastrointestinal disorders such as cholera, diarrhea or dysentery. Methods: The methanol extracts of these plants were screened for antibacterial activity against 11 strains of enteropathogenic bacteria, including multi-drug resistant Vibrio cholerae (serotypes O1, O139, and non-O1, non-O139), using broth microdilution method. Ampicillin was used as a positive reference standard to determine the sensitivity of the strains. Phytochemical screening was carried out for phenolics and flavonoids. Results: All of these plants had bactericidal activity against at least one of the test microorganisms with minimum inhibitory concentration (MIC) ranging from 0.125 to 32 mg/ml and minimum bactericidal concentration (MBC) ranging from 0.25 to 32 mg/ml. Among these, Terminalia chebula Retz. (Combretaceae) and Syzygium cumini (L.) Skeels (Myrtaceae) showed the most promising broad spectrum antibacterial properties, inhibiting all of the strains tested, especially Vibrio cholerae, Aeromonas hydrophila and Bacillus subtilis, with MBC ranging from 0.25 to 4 mg/ml. Phenolics and flavonoids were found to be present in the extracts. Conclusion: The findings provide support for the use of this plant in traditional medicine for treatment of diarrheoa, especially cholera.