SIR 2024
Renal and GU Interventions
Bo Yu, MD (he/him/his)
Internal Medicine Resident
University of Maryland Medical Center
Financial relationships: Full list of relationships is listed on the CME information page.
Samuel G. Savidge, BA (he/him/his)
Medical Student
University of Maryland School of Medicine
Financial relationships: Full list of relationships is listed on the CME information page.
Nariman Nezami, MD (he/him/his)
Associate Professor
Georgetown University Medical Center
Disclosure information not submitted.
Mohamed Ibrahim, MBBS
Assistant Professor
University of Maryland School of Medicine
Disclosure information not submitted.
This study investigated the natural history of biofilm formation in dialysis catheters, formation patterns in different parts of catheters, and factors impacting the development of biofilm.
Materials and Methods: 55 dialysis catheters were collected from patients on dialysis or apheresis. 2cm sections were obtained at the proximal, middle, and distal part of each catheter, and then longitudinally split into equal halves. Crystal violet was used for staining. Sections were photographed under a specialized DSLR camera with 1:1 macro magnification. Biofilm percent area coverage was quantified with ImageJ software.
Results:
Catheters were divided into 5 groups based on their indwelling time, Group 1: 1- 10 days, Group 2 11-30 days, Group 3 31-60 days, Group 4 61-90 days, Group 5 > 90 days. Luminal biofilm increased significantly with indwelling time, with group 5 showing significantly higher percentage coverage (83.2 ± 5.49) than all other groups, p< 0.05. Group 2 (28.95 ± 9.73), Group 3 ( 29.30 ± 5.07) and Group 4 ( 56.18 ± 34.51) also had higher biofilm coverage than group1 (11.07 ± 5.55), p< 0.05. External biofilm coverage was higher than luminal biofilm in catheters with indwelling time 1- 30 days (Group 1 + Group2) (external 19.94 vs. lumen 6.60, p= 0.04). However luminal biofilm was higher than external biofilm in catheters indwelt more than 60 days (58.86 vs. 43.36, p = 0.05). In subgroup analysis, Group 5’s top artery lumen had higher coverage than the bottom artery lumen (88.78 vs. 72.60, p = 0.01), Group 5’stop venous lumen had higher biofilm coverage than the bottom lumen (88.80 vs. 73.06, p= 0.05). In group 3, the bottom venous lumen had higher biofilm than the middle venous lumen (38.05 vs. 20.97, p= 0.01). Also, biofilm at the bottom of the venous lumen may be higher than the arterial lumen though not statistically significant (venous bottom 40.90 vs. arterial bottom 35.61, p=0.07). Intermittent Dialysis is not a risk factor compared with patients who received apheresis by univariate analysis and multivariate analysis.
Conclusion:
This is the largest study of biofilm formation in tunneled and non-tunneled dialysis catheters by far. Indwelling time is the strongest predictor of biofilm formation. The top and the bottom part of the catheter are more vulnerable to the formation of biofilm formation than the middle part, suggesting the impact of flow dynamics and exposure to the outside environment. External biofilm formation was more prominent than the intraluminal biofilms in catheters with short indwelling time, but over time luminal biofilm coverage is higher than the external surface.