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Streptococcus gordoniiRANK: SpeciesTAXONOMY: Terrabacteria group -> Firmicutes -> Bacilli -> Lactobacillales -> Streptococcaceae -> Streptococcus -> Streptococcus gordonii OVERVIEW: The genus Streptococci are gram positive, mesophilic, nonmotile cocci that grow in pairs or bead like chains. Organisms within the genus comprise both pathogenic bacteria, such as S.pneumoniae and S. pyogenes, and non-pathogenic species that inhabit the mouth, skin, intestine and upper respiratory tract of humans including S. gordonii and S. mutans. S gordonii is part of the group viridians of Strepotococci, nonpathogenic commensal streptococci, which are integral members of the human oral flora. These organisms colonize tooth surfaces by creating biofilms in the human mouth, also known as dental plaque. S.gordonii plays an integral role in initiating colonization by creating surfaces for other colonizers to adhere to. Eventually dental biofilms lead to periodontal disease and dental cavities which are two of the most common diseases in developed nations.S. gordonii also causes bacterial endocarditis by entering the blood stream usually after oral trauma. S. gordonii colonizes platelet-fibrin thrombi, blood clotting agents, in damaged heart valves or endocardium leading to damage and dysfunction of the heart valves. Endocarditis can be treated with antibiotic therapy and may cause death.Although S. gordonii initiates dental plaque and the colonization of other pathogenic bacteria on tooth surfaces, S. gordonii is not directly pathogenic in the oral cavity. On the other hand, once S. gordonii enters the blood stream via oral bleeding it can colonize damaged heart valves causing endocarditis in humans . Blood platelets, cell fragments that facilitate blood clotting, bind to fibrinogen on the damaged heart valves and endocardium, the heart’s inner lining, and form platelet-fibrin thrombi. This platelet-fibrin thrombi can become colonized by S. gordonii causing damage to the heart valves and dysfunction of the heart .During bleeding of the oral cavity more than seven hundred bacterial species may enter the blood stream although of these seven hundred, the oral streptococci are the most common causes of endocarditis . S. sanguis, S. oralis, and S. gordonii are the top three enodcarditis causing pathogens. It is curious that oral streptococci are efficient in binding to blood platelets especially since the blood stream is not their natural habitat. Recent studies have addressed this phenomenon and concluded that oral streptococci have adapted specialized mechanisms to recognize and bind with sialic-acid containg structures in the mouth, their natural habitat, which also allows for efficient interaction with platelet sialoglycoprotein GPI-alpha, located on the platelet membrane. In S. gordonii, Hsa and GspB proteins facilitate adhesion with both sialylated salivary molecules like mucin, MG2, as well as platelet surface proteins, GPI-apha and GPIIb. Clearly, an evolutionary adaptation in one habitat has allowed S. gordoniiand other oral streptococci to invade another habitat .Bacterial endocarditis occurs in humans who most often have artificial heart valves, heart disorders, or hypertrophic cariomyopathy. Dental surgery, oral trauma, urologic or gynecologic surgery, skin infections and intravenous drug use will increase the chances of endocarditis. Some symptoms of bacterial endocarditis include “fatigue, loss of appetite, night sweats, chills, headaches, joint discomfort, and tiny pinpoint-sized hemorrhages on the chest and back, fingers, or toes.” Treatment consists of intravenous antibiotic therapy and sometimes oral antibiotics for several weeks. Identified as a constituent of the oral microbiome by Human Oral Microbiome Database. Identified as constituent of vaginal microbiome. [PMID:23282177] This species has been identified as a resident in the human gastrointestinal tract based on the phylogenetic framework of its small subunit ribosomal RNA gene sequences.[PMC 4262072] |