Modulating gut microbiota for treating antibiotic-associated diarrhea from <i>Clostridium difficile</i> infection: insights from Lizhong decoction and its polysaccharide component

To investigate whether the polysaccharide component of the Traditional Chinese Medicine (TCM) formula Lizhong decoction (LZD) has therapeutic effects and regulates gut microbiota in antibiotic-associated diarrhea (AAD) related to Clostridium difficile infection, a polysaccharide was extracted from LZD, consisting of rhamnose, five monosaccharides, arabinose, galactose, glucose, and galacturonic acid in a molar ratio of 1.12:8.49:4.06:80.67:5.66. An AAD model related to C. difficile infection was established using clindamycin gavage and oral colonization with C. difficile. Subsequently, oral treatment experiments with LZD polysaccharides and different doses of the decoction were conducted. The results indicated that the polysaccharide showed the best therapeutic effect on AAD related to C. difficile infection, with post-treatment gut microbiota clustering closest to the normal control group. The polysaccharide from LZD has therapeutic effects on AAD related to C. difficile infection, possibly achieved through the regulation of gut microbiota. It modulates the dominant gut microbiota, specifically increasing the abundance of beneficial bacteria by adjusting the ratio of Bacteroidetes and Firmicutes, thereby reversing the dysbiosis caused by C. difficile infection and antibiotics. Thus, LZD polysaccharide may be one of the important active components for gut microbiota regulation in this TCM formula.