Streptococcus is a member of Gram-positive lactic acid-producing bacteria (LAB) that belonged to Firmicutes phylum. Many strains of Streptococcus are non-pathogenic and occur as commensal flora on the skin, the oral cavity, nasopharynx, upper respiratory tract, urogenital, and gastrointestinal tracts. Some species of Streptococcus are responsible for numerous human inflammatory diseases including pharyngitis, meningitis, endocarditis, necrotyzing fasciitis, and those that are immune mediated, such as acute glumeronephritis, acute rheumatic fever, and colon cancer. Interaction of some virulence factors of Streptococci with immune cells could elicit inflammatory response in different organs. Association of Streptococcusbovis with IBD and colon cancer was reported in previous studies. In one study, it was shown that Streptococci are the predominant group of bacteria in inflamed colonic mucosa of CD patients; however this association was not verified in patients with UC. Contrary to these results reduction of Streptococci in IBD patients were observed in studies that investigated health-beneficial effects of these bacteria. 

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