The Antibacterial Activity of Melittin Derived from Iranian Honeybee Venom on Clinical Isolates of Pseudomonas aeruginosa

Infections caused by Pseudomonas aeruginosa have been reported from many hospitals، and according to its opportunistic nature، Pseudomonas aeruginosa invades to immunocompromised patients and controlling the following infection is so hard. Antibiotics misusage beside complex mutation mechanisms in pseudomonas genus led to resistance against many antibiotics. During the past decade، tracing for natural antimicrobial peptide is more considered. Among them، melittin has been extracted from honey bee venom and its antibacterial activity is being examined. The main goal of this study was to evaluate antibacterial activity of melittin against clinical isolates of Pseudomonas aeruginosa. 48 Clinical strains were present from previous study. Honey bee venom was prepared using electrical stimulation and the quality of venom was confirmed by SDS-PAGE. Melittin was isolated from the venom using a linear gradient of acetonitrile and C18 column by Reverse Phase-High Performance Chromatography (RP-HPLC) Technique. Minimal Inhibition and Bactericidal concentration of melittin were examined on clinical isolates of Pseudomonas aeruginosa. Honey bee venom consisted of twenty distinct fractions in which melittin was the major one. MIC50 for melittin against all; mucoid، and non-mucoid sensitive isolates، were 12. 5، 6. 25، and 12. 5 μg respectively. Among mucoid and non-mucoid strains، 94. 73 and 86. 2 % were sensitive to melittin respectively. MBC50 for melittin against total، mucoid and non-mucoid isolates were 50، 37. 5، and 50 μg respectively. Totally، 89. 58 % were sensitive to melittin and 10. 41 % were not inhibited. The results obtained from MIC and MBC tests showed that melittin had significant inhibitory and bactericidal effect on clinical isolates of pseudomonas aeruginosa. According to the results، the less amount of melittin can suppress the growth of mucoid strain of pseudomonas. These strains due to existence of polysaccharide layers around bacteria have less permeability to antibiotics and expose more resistance. This study would be of great value to the treatment of cystic fibrosis patients with pseudomonas infections.