动物实验研究表明，肠道分节丝状菌（segmented filamentous bacteria，SFB）是一种革兰氏染色阳性梭菌；具有物种选择性定殖特性，主要定殖在回肠末端上皮细胞表面；具有调节宿主免疫系统成熟，刺激Th17细胞特异性分化和促进肠道表面免疫球蛋白A（sIgA）分泌等功能；在防御病原微生物感染和诱发自身免疫性疾病发生发展等方面发挥重要作用。虽然在众多脊椎动物中均能检测到SFB的存在，但关于人SFB的研究报道甚少。有研究表明人体肠道样品中能检测到SFB的存在，且对临床样品进行调查研究发现，人体肠道SFB与免疫调控和疾病症状等存在一定的相关性。但由于SFB在人体肠道中丰度极低，且在同一个体中可能存在不同的SFB菌株，SFB单细菌分离与纯培养仍然是进一步研究人体肠道SFB免疫调节功能的必由之路。
Intestinal Segmented Filamentous Bacteria (SFB) is a Gram-positive Clostridium spp. with selective colonization of species, as shown by experiments. SFB mainly colonize on the surface of intestinal epithelial cells at the end of the ileum, to regulate the maturation of host immune system, stimulate the specific differentiation of CD4+ Th17 cells and promote the secretion of intestinal surface immunoglobulin A (sIgA). SFB play very important roles in preventing pathogenic microbial infection and induction of occurrence and development of autoimmune diseases. Although SFB can be detected in many vertebrates, few studies have been reported on human SFB. Studies have shown that SFB can be detected in human intestinal samples, and the investigation of clinical samples shows that there is a certain correlation of SFB in human intestinal tract with immune regulation and disease symptoms. However, due to the extremely low abundance of SFB in human intestinal tract and the possible existence of different SFB strains in the same individual, isolation and pure culture of SFB single bacteria are still the only way to further study the immune regulation function of human SFB.