ABSTRACT
Background: Gastrointestinal manifestations and gut dysbiosis are prevalent after SARS-CoV2 infection.With the continuously increasing number of infected cases, more attention should be paid to this particular population in post-infection recovery.cWe aimed to investigate the potential beneficial effect of FMT on gastrointestinal symptoms, gut dysbiosis and immune status in discharged COVID-19 patients. Results: Gastrointestinal and psychological disorder (45.5%) were observed in COVID-19 patients during post-infection recovery, improvement of which were observed after FMT. Most of the lab results including blood routine and blood biochemistry, within the normal range. The general distribution of 69 different types of lymphocytes differed between before and after FMT. FMT exert significant effect on B cells which was characterized as decreased naive B cell ( P =0.012) and increased memory B cells ( P = 0.001) and non-switched B cells ( P = 0.012).The microbial community richness indicated by OTUs number, observed species and Chao1 estimators was marginally increased after FMT, whereas the community diversity estimated by the Shannon and Simpson index showed no significant changes after FMT. Gut microbiome composition of discharged COVID-19 patients differed from that of the general population at both phylum and genera level, which was characterized with a lower proportion of Firmicutes (41.0%) and Actinobacteria (4.0%), higher proportion of Bacteroidetes (42.9%) and Proteobacteriato (9.2%). FMT can partially restore the gutdysbiosis by increasing the relative abundance of Actinobacteria (15.0%) and reducing Proteobacteriato (2.8%) at the phylum level. At the genera level, Bifidobacterium and Faecalibacterium , which were dominant genera in the human gut microbiota and were beneficial for human health, had significantly increased after FMT. Conclusions: Gastrointestinal and gut dysbiosis were observed in COVID-19 patients during post-infection recovery. FMT can improve the immune functionality, restore the gut microbiota, alleviate gastrointestinal disorders, and may serve as a potential therapeutic and rehabilitative intervention for the COVID-19.