Abstract: Objective To explore the difference in intestinal flora composition between individuals with sub-health status and healthy subjects. Methods From November, 2020 to May, 2021, a total of 150 nursing staff members in Nanfang Hospital were selected for this study, including 75 participants with sub-health status (SHS group) and 75 healthy participants (control group). Fecal samples were collected from all the participants for analysis of the diversity and species composition of the intestinal flora using high-throughput sequencing for V3-V4 region of 16S rRNA gene. Results The results of α diversity analysis showed no significant difference in Chao1 index between the two groups (P=0.619), but the Shannon index was significantly higher in SHS group than in the control group (P<0.001). The results of β diversity analysis showed significant differences in the community structure between the SHS group and the control group (R=0.227, P=0.001). At the phylum level, the intestinal flora in the two groups were composed mainly of Bacteroidota, Firmicutes and Actinobacteriata, and of Prevotella, Bacteroides, Blautia and Faecalibacterium at the genus level. Species difference analysis identified significant differences in the relative abundance between the two groups in 4 phyla, 3 classes, 3 orders, 3 families and 3 genera (P<0.05). Conclusion Compared with healthy subjects, the individuals with sub-health status have obviously unbalanced structure of the intestinal flora.

Key words: sub-health status; intestinal flora; 16S rRNA; chronic fatigue syndrome