Inhibitory effect of Cinnamaldehyde and Carvacrol with honey on genes expression of exoS and ampC of pseudomonas aeruginosa multidrug resistant isolates recovered from burn wound infection

Background and Aim : Background Due to the resistance of Pseudomonas aeruginosa to most antibiotics, various strategies are used to its treatment, one of which is the use of medicinal plants. This study aimed to evaluate the effect of Cinnamaldehyde and Carvacrol with honey on expression of exoS and ampC genes of Pseudomonas aeruginosa multidrug resistant isolates recovered from burn wound infection. Methods : Thirty-five P. aeruginosa isolates were recovered from clinical samples. These samples were taken by consecutive sampling from burn wound infection of patients admitted to the burn ward of Besat hospital of Hamadan, Iran, during 2018. Antibiotic susceptibility testing was performed using Kirby-Bauer disk diffusion method to identify MDR isolates. The antibacterial effect of Cinnamaldehyde, and Carvacrol with honey was compared to Imipenem (as control group) using broth dilution method based on CLSI 2018 guidelines. The inhibitory effect of the extracts with honey was studied alone and in combination, the inhibitory effect of mentioned compound in Sub-MIC concentration was investigated on expression of exoS and ampC genes compared to Imipenem by Real-Time-PCR. Then, data analyzed using SPSS software and t-test, Kruskal-Wallis, and Mann-Whitney tests. P-value less than 0.05 were considered significant. Results : The minimum inhibitory concentration (MIC) of Cinnamaldehyde was 0.82 to 0.01% μg/mL, Carvacrol 0.01- 0.6 μg/mL, and honey 62.5 - 250 μg/mL. MIC of the mentioned compound 430 times was lower than Imipenem. Overall, the mentioned compound showed a synergistic effect on 70% of the isolates. At sub-MIC concentration, this combination reduced the expression of exoS and ampC genes by 6.12 and 2.85 fold, respectively. Conclusion : The combination of Cinnamaldehyde, and Carvacrol with honey showed a higher antibacterial effect than Imipenem. Of course, with more isolates this should be confirmed.

Keywords:

Pseudomonas aeruginosa , Gene expression , Cinnamaldehyde , Carvacrol , Honey , Multi-drug resistance