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Unique microbial profiles and severity-associated alterations in the peritoneal fluid of children with acute
Tsubasa Aiyoshi1, Tomo Kakihara2, Eiichiro Watanabe3
1Department of Pediatric Surgery, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan; Laboratory for Symbiotic Microbiome Sciences, RIKEN Center for Integrative Medical Sciences, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.
Insights
The peritoneal fluid microbiota in children with appendicitis differs from the appendix lumen microbiota and changes with appendicitis severity. This impacts understanding of intra-abdominal abscess development after appendectomy.
Area of Science:
- Microbiology
- Pediatric Surgery
- Gastroenterology
Background:
- Intra-abdominal abscesses (IAA) post-appendectomy stem from residual bacteria.
- The peritoneal fluid (PF) microbiota in pediatric acute appendicitis (AA) lacks thorough characterization using culture-independent methods.
- This study investigates PF microbiota in pediatric AA using next-generation sequencing.
Purpose of the Study:
- To characterize the peritoneal fluid microbiota in children with acute appendicitis.
- To compare PF microbiota with appendiceal lumen microbiota.
- To explore correlations between PF microbiota composition and appendicitis severity.
Main Methods:
- Prospective observational study of 21 pediatric AA patients undergoing appendectomy.
- Collection of peritoneal fluid (PF) and appendiceal lumen samples.
- 16S rRNA amplicon sequencing for microbiota analysis.
Main Results:
- Key PF bacterial genera include Bacteroides, Parvimonas, Prevotella, Streptococcus, Blautia, and Fusobacterium (≥5% relative abundance).
- PF microbiota composition significantly correlates with serum C-reactive protein (CRP) levels (P=0.011).
- Significant differences in microbiota composition and diversity were observed between simple appendicitis (SA) and complicated appendicitis (CA), and between PF and appendiceal lumen.
Conclusions:
- The peritoneal fluid microbiota has a distinct composition compared to the appendiceal lumen.
- PF microbiota alterations correlate with AA severity, reflecting inflammatory response (CRP) and pathological classification (SA vs. CA).
- Findings offer novel insights into the pathogenesis of postoperative intra-abdominal abscesses.
Background:
Intra-abdominal abscesses (IAA) after appendectomy for acute appendicitis (AA) result from residual bacteria in the abdominal cavity. However, the microbiota of the peritoneal fluid (PF) in children with AA has not been well-characterized, particularly through culture-independent methods. This study aimed to characterize the PF microbiota using next-generation sequencing.
Methods:
This observational study prospectively enrolled 21 pediatric AA patients (simple appendicitis [SA], n = 11; complicated appendicitis [CA], n = 10) who underwent appendectomy. PF and appendiceal lumen samples were collected, and their microbiota was analyzed using 16S rRNA amplicon sequencing.
Results:
The most abundant bacterial genera in the PF microbiota were Bacteroides, Parvimonas, Prevotella, Streptococcus, Blautia, and Fusobacterium, each exhibiting an average relative abundance of ≥5 %. Redundancy analysis revealed a significant correlation between serum C-reactive protein levels and the composition of the PF microbiota (P = 0.011). In addition, nine bacterial genera showed significantly higher relative abundances in SA than in CA. The microbiota of the PF and appendiceal lumen differed regarding alpha- and beta-diversity and the average relative abundance of 19 bacterial genera.
Conclusion:
The PF microbiota exhibits a unique composition distinct from that of the appendiceal lumen. Furthermore, it demonstrates alterations associated with the severity of AA, reflecting both the degree of inflammatory response, as indicated by serum CRP levels, and pathological severity, as defined by the distinction between SA and CA. These findings provide new insights into the pathogenesis of postoperative IAA.
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