The Effect of Ferula assa-foetida L and Carum copticum Hydroalcoholic Extract on the Expression Levels of Staphylococcus aureus Genes Involved in Quorum Sensing.

BACKGROUND: Quorum sensing is a microbial cell-to-cell communication process. Quorum sensing bacteria produce and release extracellular messenger molecules called autoinducers. Gram-positive and Gram-negative, homoserine lactones, and oligopeptides are autoinducers used to communicate and regulate gene expression.

OBJECTIVES: The goal of this study was to assess the impact of subinhibitory concentrations of Ferula assa-foetida l oleo-gum resin and Carum copticum fruit on the expression of tst and hld genes of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains.

METHODS: This analytical study was performed using standard strains of MRSA (ATCC 33591) and MSSA (ATCC 29213). Suspensions of MRSA and MSSA bacteria were incubated at 37°C for 7 and 16 hours in the presence of ethanol extracts from F. assa-foetida and C. copticum. The expression of the hld and tst genes was then assessed using the real-time PCR protocol and SYBR Green Master Mix. The data analysis was carried out using the 2(-ΔΔCT) method.

RESULTS: The hld gene expression (RNAIII) of MRSA after 7 and 16 hours of exposure to the sMIC of the F. assa-foetida extract showed a fold change of -1 and 0.08, respectively, in comparison with controls. After 7 and 16 hours of exposure to the sMIC of the C. copticum extract, the fold change was -0.23 and -0.27, respectively. After exposure to the sMIC of the C. copticum extract for 16 hours, the fold change in the expression of the tst (TSST-1) MSSA gene was 0.37 lower than that of the control sample.

CONCLUSIONS: The results indicate that sMICs of ethanol extracts from F. assa-foetida and C. copticum can be used to control the expression of virulence genes in pathogenic bacteria, such as MRSA and MSSA.