Abstract

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.