Antibacterial Activity of Aqueous and Methanolic Extracts of Crocus sativus Stigma and Cinnamomum cassia against Clinical Isolates of some Gram-Positive and Gram-Negative Pathogenic Bacteria

Background and Objectives: Medicinal and aromatic plants are sources of natural antimicrobial compounds that could be useful replacements for antibiotics. The aim of this study was to assess antimicrobial activity of Crocus sativus stigma and Cinnamomum cassia extracts against some Gram-positive and Gram-negative bacteria. Methods: Antimicrobial activity of methanolic and aqueous extracts of the plants was tested against clinical isolates of Klebsiella pneumonia, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Enterococcus using the microdilution method. Minimal inhibitory concentration (MIC) and minimum bactericidal concentration of each extract against the mentioned bacteria were also determined. Results: The MIC of the methanolic extract of C. cassia was 80 μg/ml against Enterococcus, K. pneumonia and E. coli. The MIC of the methanolic extract of C. sativus was 160 μg/ml against Enterococcus and S. aureus. The minimum bactericidal concentration of the methanolic extracts of C. sativus and C. cassia was 320 μg/ml against K. pneumonia and 160 μg/ml against Enterococcus. Conclusion: The extracts of C. sativus and C. cassia exhibit promising antibacterial activities against clinical isolates of the tested bacteria. Our results suggest that the extract of these plants can be further exploited as potential antibacterial agents against multi-drug resistant bacteria.