ANTIMICROBIAL ACTIVITY OF EUGENOL AGAINST HUMAN PATHOGENIC BACTERIA BY MINIMAL INHIBITORY CONCENTRATION, MINIMAL BACTERICIDAL CONCENTRATION AND DISC-DIFFUSION METHODS

Essential oils from plants have been reported to have antibacterial activity. Essential oil is a mixture of many chemicals, and one or more chemicals in essential oil may have antibacterial activity. In our laboratory, essential oil from the leaves of Ocimum sanctum L. was found to have antibacterial activity against 18 human bacteria. GC-MS analysis of the Ocimum sanctum essential oil revealed the presence of 19 chemicals, and one of them was eugenol. In the present study, eugenol was found to have an antibacterial effect against 4 Gram-negative and 2 Gram-positive human pathogenic bacteria by minimal bactericidal concentration, minimal inhibitory concentration and disc-diffusion methods. The minimal bactericidal concentrations of eugenol were 0.96 mg/ml, 4.17 mg/ml, 16.6 mg/ml, 16.6 mg/ml, 33.3 mg /ml and 33.3 mg /ml against Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Serratia marcescens and MRSA, respectively. The minimal bactericidal concentrations and minimal inhibitory concentrations in Gram-negative bacteria Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Serratia marcescens were similar. The minimal inhibitory concentrations are more than those of minimal bactericidal concentrations of Gram-positive bacteria, MRSA, and Staphy-lococcus aureus. The diameters of growth inhibition by eugenol were 7, 10, 10, 14, 15, and 23 millimeters for Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens, Staphylococcus aureus, MRSA, and Acinetobacter baumannii, respectively.