Abstract: TH-PO0460
Unmasking Hidden Pathogens: Nanopore 16S rDNA Sequencing Reveals Site-Specific Microbial Signatures in Hemodialysis Catheters
Session Information
- Hemodialysis: Novel Markers and Case Reports
November 06, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Dialysis
- 801 Dialysis: Hemodialysis and Frequent Dialysis
Authors
- Kanjanabuch, Talerngsak, Division of Nephrology, Department of Medicine and Center of Excellence in Kidney Metabolic Disorders, Faculty of Medicine, Chulalongkorn University, Pathum Wan, Bangkok, Thailand
- Somtha, Baramett, Program in Medical Sciences, Faculty of Medicine, Chulalongkorn University, Pathum Wan, Bangkok, Thailand
- Visedthorn, Suthida, Center of Excellence in Systems Microbiology (CESM), Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Pathum Wan, Bangkok, Thailand
- Bunma, Chainarong, Center of Excellence in Systems Microbiology (CESM), Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Pathum Wan, Bangkok, Thailand
- Chanchaem, Prangwalai, Center of Excellence in Systems Microbiology (CESM), Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Pathum Wan, Bangkok, Thailand
- Saejew, Thunvarat, Division of Nephrology, Department of Medicine and Center of Excellence in Kidney Metabolic Disorders, Faculty of Medicine, Chulalongkorn University, Pathum Wan, Bangkok, Thailand
- Pavatung, Preeyarat, Division of Nephrology, Department of Medicine and Center of Excellence in Kidney Metabolic Disorders, Faculty of Medicine, Chulalongkorn University, Pathum Wan, Bangkok, Thailand
- Payungporn, Sunchai, Center of Excellence in Systems Microbiology (CESM), Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Pathum Wan, Bangkok, Thailand
Background
Catheter-related bloodstream infections (CRBSIs) are a major threat in HD. Conventional cultures often miss fastidious or biofilm-residing organisms. Nanopore 16S rDNA sequencing offers rapid, culture-independent identification of catheter-colonizing bacteria, providing a broader view of CRBSI pathogenesis.
Methods
We performed 16S rDNA (V1–V4) amplicon sequencing using Oxford Nanopore MinION on 140 HD catheter segments (70 arterial [site A], 70 venous [site V]) removed from adult CKD patients. DNA was extracted from biofilms, basecalled with Guppy, and analyzed via QIIME2 and NanoCLUST using the RDP database. Diversity indices (Chao1, Shannon) and beta diversity (PERMANOVA) were compared across clinical subgroups (CRBSI vs. non-CRBSI, permcath vs. double-lumen, survival vs. death), and taxonomic differences were explored.
Results
All samples yielded amplifiable 16S rDNA, with 100% positivity by sequencing vs. <5% by culture. Site A and V harbored significantly different microbial communities (Chao1 p=2.27e-06; Shannon p=0.01; beta diversity p=0.02). Site A was enriched with host-derived bacteria (e.g., Staphylococcus, Enterococcus, Escherichia), while site V showed a predominance of waterborne pathogens, including Pseudomonas fluorescens, Ralstonia pickettii, Holophaga foetida, and Phyllobacterium myrsinacearum, implicating water treatment and dialysis machinery as potential reservoirs. Subgroup comparisons showed no significant diversity differences between CRBSI vs. non-CRBSI (site A: Chao1 p=0.46, Shannon p=0.20, beta p=0.48; site V: Chao1 p=0.09, Shannon p=0.08, beta p=0.70) or between catheter types (site A and V: all p>0.3). In mortality analysis, site V in non-survivors trended toward higher microbial diversity (Shannon p=0.08; beta diversity p=0.05), suggesting a possible link between environmental colonization and adverse outcomes.
Conclusion
Nanopore 16S sequencing revealed widespread polymicrobial colonization and distinct arterial vs. venous profiles. Environmental organisms in venous limbs of the catheters likely reflect dialysis infrastructure contamination. These findings highlight its value as a diagnostic and infection control tool in HD care.
Funding
- Government Support – Non-U.S.