Irritable bowel syndrome (IBS) is a functional bowel disorder featured by recurrent abdominal pain and changes in defecation habits, seriously impairing the quality of life of patients. The effects of widely used treatment targeting gut dysbiosis in IBS patients are reported to be various. There are no unified conclusions on the association between gut microbiota status and treatment, and post-treatment changes in gut microbiota. So there is a lack of high-quality evidence for microbiota-targeted treatment in IBS.

To analyze the effect of common microbiota-targeted therapies on gut microbiota in patients with IBS.

The databases of Web of Science Core Collection, PubMed, Embase and Cochrane Library were searched from inception to May 20, 2022 for studies about the changes of gut microbiota after treatment with one kind of probiotics, prebiotics, antibiotics and fecal microbiota transplantation (FMT) . The data including first author, country, publication year, diagnostic criteria, IBS subtype, sample size, drug type, route and location of FMT, dose and course of treatment, sample and method of microbiota detection, and results of microbiota detection were extracted, and the research results were summarized and reported.

In total, 3 044 studies were retrieved, and 41 of them were included according to inclusion and exclusion criteria, including 11 on probiotics, 8 on prebiotics, 5 on antibiotics and 17 on FMT. Randomized controlled trials accounted for the largest percentage of the total. The most frequently used diagnostic criteria was Rome Ⅲ criteria. IBS with diarrhoea was the most prevalent IBS subtype. The 16S rRNA amplicon sequencing was the mostly used technique for microbiome analysis. Lactobacillus was the most common bacterial strains used as probiotics, which can maintain its activity in the feces of IBS patients. Prebiotics could facilitate the colonization of probiotics (mainly Bifidobacteria) in feces and colonic mucosa. Rifaximin, an antibiotic acting locally in the intestine, could reduce the species richness of the microbiota, but had no significant effect on the microbial structure. After FMT, the microbial structure of IBS patients tended to be similar to that of donors, with increased probiotics and reduced abundance of pathogenic bacteria.

Treatment targeting microbiota, including probiotics, prebiotics, nonabsorbable antibiotics and FMT, is helpful for the improvement and reconstruction of intestinal microenviroment in IBS patients. More accurate post-treatment changes of microbiota will be obtained by unifying the diagnostic criteria, using more advanced detection technique, and controlling the follow-up time accurately, thereby providing a basis for clinical development of accurate microbiota-targeted intervention strategies.