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Clinical Gastroenterology
IDDF2024-ABS-0172 A potential intestinal pathogen for autism spectrum disorder: fecal enterotoxigenic bacteroides fragilis
  1. Mengqi Xu1,
  2. Xi Luo2,
  3. Huijun Zhao3,
  4. Wenjie Xi4,
  5. Yiyuan Li1,
  6. Xinjun Wang5,
  7. Huanlong Qin5,
  8. Jingshuang Yan1,
  9. Fei Pan1,
  10. Zikai Wang1,
  11. Liping Zou2,
  12. Lihua Peng1,
  13. Yunsheng Yang1
  1. 1Microbiota Laboratory, Clinical Division of Microbiota, Department of Gastroenterology and Hepatology, The First Medical Center, Chinese PLA General Hospital, China
  2. 2Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, China
  3. 3Department of Gastroenterology, National Center for Children’s Health, Beijing Children’s Hospital, Capital Medical University, Beijing, China
  4. 4Beijing Tongren Hospital, Capital Medical University, China
  5. 5Shanghai Institution of Gut Microbiota Research and Engineering Development, Tenth People’s Hospital of Tongji University, China

Abstract

Background The gut microbiota is closely associated with autism spectrum disorders (ASD), but the specific microorganism involved is not well understood. Bacteroides fragilis has been implicated in ASD in rodent models, though the evidence is inconclusive. B. fragilis exhibits remarkable genetic diversity and can be categorized into enterotoxigenic B. fragilis (ETBF) or non-toxigenic B. fragilis (NTBF). We aimed to investigate the potential role of B. fragilis in the ASD population.

Methods Fecal samples were collected from 70 individuals with ASD, 45 individuals with Tic disorder (TD) as disease controls, and 64 healthy controls (HC) for PCR analysis to identify B. fragilis and ETBF. In five ASD children who were ETBF (+) and received fecal microbiota transplantation (FMT) treatment, we compared the ETBF copy number by quantitative PCR before and after FMT.

Results There was no significant difference in the detection of B. fragilis between the ASD, TD, and HC groups, whereas ETBF was higher in ASD than in TD (21.43% vs. 6.67%, P = 0.0335) and HC (21.43% vs. 7.81%, P = 0.0272) (IDDF2024-ABS-0172 Figure 1. Stacked histogram of B. fragilis and subtype in ASD TD and HC children). Among five ASD children who tested positive for ETBF and received FMT treatment, 80% (4/5) showed a clinical response, a 4.5-point decrease in the CARS-2 score. Four cases had a reduction in their CARS-2 score by 5.5-6.5 and a decrease in ETBF copy number by over 90%. One non-responding case had a 2-point decrease in their CARS-2 score and a 49.88% decrease in ETBF copy number (IDDF2024-ABS-0172 Figure 2. Cars 2 scores and fecal ETBF copy number was reduced after FMT treatment in five ASD children).

Abstract IDDF2024-ABS-0172 Figure 1
Abstract IDDF2024-ABS-0172 Figure 1

. Stacked histogram of B fragilis and subtype in ASD TD and HC children.

Abstract IDDF2024-ABS-0172 Figure 2
Abstract IDDF2024-ABS-0172 Figure 2

Cars 2 scores and fecal ETBF copy number was reduced after FMT treatment in five ASD children.

Conclusions The detection rate of ETBF was higher in ASD than in TD and HC children. FMT efficacy was correlated with ETBF, which may be a predictor of FMT efficacy for ASD. ETBF is a potential intestinal pathogen and biomarker for diagnostic and therapeutic targets for ASD.

https://doi.org/10.1136/gutjnl-2024-IDDF.268

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