Relative Abundance of <i>Streptococcus</i> spp. and its Association with Disease Activity in Inflammatory Bowel Disease Patients Compared with Controls

Abstract

Background: Some studies show that the gut microbiota is an essential risk factor in driving inflammatory bowel disease (IBD). There are some evidences regarding the involvement of Streptococcus spp. in the pathogenesis of IBD. In this study we compared proportions of Streptococcus spp. in feces of IBD patients and control volunteers. Methods: The freshly prepared stool samples were collected from 29 patients with IBD and 29 healthy volunteers. Disease activity was measured by means of standard clinical indices. Total DNA was extracted from the stool samples and used for relative quantification of Streptococcus spp. based on the real-time PCR method in the patient’s and control’s groups. Results: Results showed a relative increase in abundance of Streptococcus spp. (0.0006 to 34.2 fold increase) and greater population diversity among IBD patients compared with the control group (mean ± standard deviation 2.94 ± 0.37 versus 1.07 ± 0.31). Patients with increased Streptococcus spp. levels represent a higher rate of neutrophil and lymphocyte infiltration than those with the lower levels; however, this increase was not statistically significant. Analysis of body mass index indicated a significant difference between IBD patients and healthy people (P value 0.02). Conclusions: The determined correlation between increases in abundance of Streptococcus spp. and IBD suggests possible involvement of this bacterial genus in promotion or severity of the disease.