Real-time RT PCR Evaluation of the Xylitol Effect on the Expression of Streptococcus pneumoniae cpsB,cpsD and psaA Genes

Background and Objective: The major pneumococcal pathogenesis factor is the capsular polysaccharide. the production of polysaccharide is regulated by cpsB and cpsD genes. Thus, every agent that induce or inhibition of expression of these genes probably increased pathogenesis of bacteria, intracellular survival and vis versa. The aim of this study was to assay the effect of Xylitol on Streptococcus pneumoniae cpsB, cpsD, psaA and aroE genes expression by Real Time RT-PCR. Materials and Methods: During 2019 in Baqiyatallah university laboratories, 20 clinical isolates and a reference strain Streptococcus pneumoniae (ATCC 6305) were studied. To assay the effect of Xylitol and fructose، different concentration of these sugars were exposed to BHI Broth media. Thereafter, the bacterial suspension was added to 5% Xylitol, 5%Xylitol + 5% fructose and control medium for 3hours. RNA was extracted and cDNA synthesis was carried out. Then, the cpsB, cpsD and psaA genes expression levels were measured. Results: The mean of cpsB gene expression ratio in presence of the % 5 Xylitol treated media compared with those in the control media and % 5 Xylitol + 5% fructose were 0.022 and 0.027 respectively. The means of the cpsD and psaA genes expression ratio in the % 5 Xylitol treated media compared with those in the control media and % 5 Xylitol + 5% fructose were 1.659 and 0.056, and 0.633 and 3.294 respectively. Conclusion: Our finding revealed that, the 5% Xylitol inhibit the cpsB gene expression properly. Therefore, it is possible to use of Xylitol for reductive on cpsB gene expression and superficial pneumococcal infections control.