Evaluation of antimicrobial activity of Curcumin nanoparticles on the gene expression of the enterococcal surface protein, Esp, involved in biofilm formation of Enterococcus Faecalis

Antibiotic-resistant forms of Enterococcus faecalis, the second leading cause of severe nosocomial infections, have begun to emerge worldwide. Evidences have shown that the Esp expression is related to the primary adherence and biofilm formation of E. faecalis. The present study investigated the effect of curcumin nanoparticles on the Enterococcal surface protein, Esp, involved in biofilm formation of antibiotic-resistant forms of enterococcus faecalis. 

In this study, 60 clinical specimens collected from patients admitted to major hospitals of Tehran, Iran and all specimens were identified by standard bacteriological and biochemical methods. The strains were evaluated for the presence of Esp in E. faecalis by PCR method. After treatment, broth microdilution method and Real-time PCR were used to assess the inhibitory activity of curcumin nanoparticles on biofilm formation and the expression level of Esp gene, respectively.

Twelve E. faecalis harboring Esp gene strains were included. The result of MIC testing and gene expression assay showed that curcumin nanoparticles did not show any inhibitory activity against biofilm formation in clinical isolates of E. faecalis and no significant changes in transcription were observed.

Considering the high prevalence of Esp gene among E. faecalis strains, molecular identification might serve as a potent drug-resistant marker of E. faecalis, as essential elements of E. faecalis for effective infection control program. No significant changes in transcription were detected when the minimal medium was supplemented with curcumin nanoparticles, suggesting that these nanoparticles contribute very little, if at all, to inhibition of the Esp operon.