Comparative Study of Garlic Extract Effect on the Expression of Genes Involved in Quorum Sensing in Pseudomonas aeruginosa and the Antibiotic Tobramycin

Abstract

Background: The expression of most genes involved in pathogenesis in Pseudomonas aeruginosa is controlled and regulated by a gene system called quorum sensing (QS). The purpose of this study was to investigate the quorum quenching of garlic extract in preventing the expression of genes involved in QS system of P. aeruginosa. Methods: In the present cross-sectional study, 12 P. aeruginosa strains were collected from burn wounds, cultured on special media and then confirmed by differential tests. The PCR test was performed to detect the lasI and lasR genes. The expression level of lasI gene was assessed in the presence of garlic extract and tobramycin antibiotic by real-time PCR, and the active ingredient of garlic extract was analyzed by HPLC. Results: Examination of 12 strains cultured on special and differential media showed that all 12 strains were P. aeruginosa. The PCR results indicated that all strains had 100% lasI and lasR genes. The real-time PCR results also revealed that the garlic extract was able to reduce the expression level of lasI gene in P. aeruginosa. It was found that tobramycin has a greater ability to reduce the expression level of this gene compared with garlic extract. Conclusion: This study showed that the garlic extract could reduce the expression of lasI gene in P. aeruginosa isolates, and that the active ingredients of this extract could be used to treat infections as an alternative to antibiotic therapy.

Keywords

• pseudomonas aeruginosa
• garlic extract
• tobramycin
• quorum sensing