Rifaximin, a rifamycin derivative, was developed by Alpha Company of Italy. It was listed in Italy as an anti infective diarrhea drug in 1987, and has been widely used abroad since then. It was approved by SFDA in 2004 and has been clinically used in China. Rifamycin is a semi synthetic antibiotic with broad antibacterial spectrum and strong antibacterial effect. It can form a high blood concentration in the intestinal tract. It can inhibit Staphylococcus aureus and Streptococcus faecalis in Gram-positive aerobic bacteria, Salmonella, Shigella, Escherichia coli and Yersinia enterocolitica in Gram-negative aerobic bacteria, Bacteroides in gram positive anaerobes have high antibacterial activity. Its mechanism of action is to inhibit the bacterial polymerase, block the transcription of RNA, and then inhibit the synthesis of bacterial protein, thus reducing the production of ammonia. Its antibacterial effect is characterized by: 1) strong antibacterial force, broad antibacterial spectrum, bactericidal effect on most Gram-positive bacteria and Gram-negative bacteria (including aerobic and anaerobic bacteria), and stronger effect on Gram-positive bacteria than Gram-negative bacteria; 2) It is not absorbed by the gastrointestinal tract and has high concentration in the intestinal tract. It can rapidly play an antibacterial role in the local area by killing intestinal pathogens, and does not need to be combined with the use of intestinal antispasmodics and adsorbents.