ABSTRACT
Useful effects of many medicinal plants were reported in the literature, among which antibacterial, antiviral and antifungal effects are the most important. In the present study, antibacterial effects of eugenol was examined. Experimental study. Serial dilution antibiotic susceptibility tests were performed to determine minimum inhibitory concentration [MIC] and minimum bactericidal concentration [MBC] against different Gram positives bacterial species including: Staphylococcus aureus, Sterptococcus agalactiae, Corynebacterium Pseudotuberculosis, Enterococcus faecalis, Bacillus cereus, Clostridium perfringens, and Listeria monocytogenes serotype 4b and Gram negative including: Escherichia coli K12 serotype, Salmonella typhimurium P649 serotype, Pasteurella multocida, and Pseudomonas aeruginosa]. MIC values for different bacterial species varied from 10 microg/ml for Pasteurella multocida to more than 6 mg/ml for Pseudomonas aeruginosa. MBC values were mostly the same as corresponding MICs. In addition, Pasteurella multocida and Streptococcus agalactiae showed comparable susceptibilities to eugenol and its sodium salt, but other microorganisms had greater susceptibility to eugenol than its sodium salt. Bacterial species of this experiment had different sensitivities to eugenol and its sodium salt