关键词: 疲劳综合征, 慢性；年龄组；肠道菌群；不动杆菌属；丹毒丝梭菌属；西南地区；16S rRNA

Abstract: Background Chronic fatigue syndrome（CFS）is a chronic debilitating disease of unknown etiology associated with intestinal microecological dysregulation and disturbances in bacterial metabolism，and there are significant differences in the composition of the intestinal flora and intestinal permeability between patients with CFS and healthy populations，but the characteristics of the intestinal flora suggestive of CFS populations of different ages have rarely been reported. Objective To explore the characteristics of intestinal flora of CFS patients in different age groups，and to provide scientific basis for risk prevention and control of CFS in different age stages. Methods CFS patients from outpatient clinics of Sichuan Integrative Medicine Hospital between February 2021 and October 2021 were selected as the study subjects，and three attending physicians were responsible for the diagnosis，60 cases were included，and divided into three groups：20 cases in the young group（18-34 years old），20 cases in the middle-aged group（35-55 years old），and 20 cases in the old-aged group（56-80 years old）. Basic information of the cases was collected，stool specimens were collected，and 16S rRNA high-throughput sequencing was used to detect the intestinal flora，and bioinformatics and statistical analysis were performed. Results Differences in species composition and relative abundance were observed in CFS patients of different ages，with higher Shannon's and Pielou's indices of intestinal flora in the old-aged group，with statistically significant differences compared to the middle-aged group（P<0.05）， and significant separation of the aggregated flora in the middle-aged group from the other two groups（P<0.01）. Coprococcus， Megamonas，Dialister，and Acinetobacter were the core flora of the young group，and Ruminococcus was the core flora of the old group. The relative abundance of Pseudomonadales，Moraxellaceae，and Acinetobacter in the young group was higher than the middle-aged and old-aged groups（P<0.05）. The relative abundance of Erysipelatoclostridium and Sellimonas in the middleaged group was higher than the young and old-aged groups（P<0.05）. The relative abundance of Eggerthellaceae and Bilophila in the old-aged group was higher than the young and the middle-aged group（P<0.05）. Conclusion There are differences in the diversity and composition of the intestinal flora of CFS patients in different age groups，and it was initially found that Acinetobacter and Erysipelatoclostridium can be used as the key flora to differentiate the intestinal flora of old-aged，middle-aged and young CFS patients.

Key words: Fatigue syndrome, chronic；Age groups；Intestinal flora；Acinetobacter；Erysipelatoclostridium；Southwest China；16S rRNA