Gene Expression of clfA , clfB, and SdrC Genes of Staphylococcus aureus Under Probiotic Stress

Abstract

     The significant factor that participated in virulence and pathogenesis for Gram-positive pathogen Staphylococcus aureus is biofilm development. In hospital settings, biofilm construction on medical equipment is quite concerning since it is a permanent source of infection. The infection results from S. aureus biofilm, which was considered a serious problem due to the difficulty in treating it with traditional antibiotics. In recent years, the medical community has been using probiotic bacteria to suppress biofilm development. The current work aims to investigate the impact of cell-free supernatant (CFS) of lactobacillus acidophilus on biofilm generation and gene expression of some key adhesion genes (clfA, clfB, and SdrC) in S. aureus clinical isolates. The CFS was extracted from Lactobacillus. acidophilus, and minimum inhibitory concentration was estimated. The colorimetric method was carried out to detect the impact of sub-minimum inhibitory concentrations of the CFS extracts on biofilm construction in thirty-three S. aureus isolates. Moreover, the expression level of some associated biofilm genes (clfA, clfB, and SdrC) was determined quantitatively before and after CFS treatment using real-time PCR for three isolates forming a strong biofilm. The result indicated that most isolates formed mostly strong and moderate biofilm with 42.42% and 48.48%, respectively, while 6.06% and 3.03% of isolates were weak and non-biofilm former. Regarding the clfA gene, gene expression was only detected in two isolates by which one isolate showed downregulation with a fold change value (0.0883) and another isolate showed upregulation with a fold change value (5.7134) after treatment of isolates with CFS. However, clfB and sdrC revealed a decrease in expression in two isolates, while the third isolate showed upregulation after treatment of isolates with CFS. The above result indicates that clfA, clfB, and sdrC expressed downregulation under the effect of CFS. In conclusion, the ability to produce biofilm plays a significant role in pathogenicity and antibiotic resistance in S. aureus isolates, especially when most isolates produce strong and moderate biofilm. Furthermore, the highly inhibitory effect of CFS from lactobacillus acidophilus in the reduction of biofilm activity and the drop in expression of key biofilm genes in S. aureus isolates highlights the capacity to use CFS as an alternative strategy to eliminate infection related to biofilm in this pathogen.