SIR 2024
Nonvascular Interventions
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.
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.
Trevor J. Mathias, PhD
Medical Student
University of Maryland School of Medicine
Disclosure information not submitted.
Mohamed Ibrahim, MBBS
Assistant Professor
University of Maryland School of Medicine
Disclosure information not submitted.
Nariman Nezami, MD (he/him/his)
Associate Professor
Georgetown University Medical Center
Disclosure information not submitted.
Infection is a common complication in patients with indwelling percutaneous nephrostomy catheters. It is widely thought that biofilm formation precedes infection, and catheter removal is necessary for treatment. However, no study thus far has characterized catheter bacterial seeding and biofilm development in indwelling nephrostomy catheters.
Materials and Methods:
38 nephrostomy catheters were obtained from patients undergoing catheter exchange. Catheters were longitudinally split into equal halves and three 2 cm portions were stained with crystal violet to allow percent area biofilm coverage quantification of the internal surface and external surface. Cross sections were cut from the middle portion and imaged with 1:1 magnification to enable measurement of internal biofilm thickness. Quantification was done with ImageJ software. Microscopic urinalysis was performed on urine samples collected from the indwelling catheter immediately prior to exchange and from the new catheter immediately after exchange and analyzed for urine leukocytes and bacteria per high-power field.
Results:
Indwelling time had a significant, positive correlation to biofilm coverage of the internal surface (β=0.15, p=0.0004), biofilm coverage of the external surface (β=0.074, p=0.0062), and biofilm thickness (β=0.27, p< 0.0001). The average biofilm coverage of the catheter internal surface was 21.1 ± 17.0% at 0-2 weeks (n=3), 27.2 ± 7.6% at 2-4 weeks (n=4), 37.7 ± 11.3% at 1-2 months (n=10), 66.4 ± 29.5% at 2-3 months (n=11), 80.6% ± 3.4 at 3-4 months (n=7), and 96.4 ± 3.3% at >6 months (n=3). Average biofilm thickness was 34 ± 9 µm at 0-2 weeks (n=3), 52 ± 6 µm at 2-4 weeks (n=4), 74 ± 16 µm at 1-2 months (n=10), 118 ± 37 µm at 2-3 months (n=11), 125 ± 20 µm at 3-4 months (n=7), and 174 ± 4 µm at >6 months (n=3) . Catheter exchange resulted in a reduction in bacteria per high-power field (p=0.0187) and a reduction in mean urine leukocytes (p=0.0004).
Conclusion: This is the first human study to characterize biofilm progression in nephrostomy catheters. Biofilm formation begins days after implantation and gradually progresses over time covering over half the internal surface by 2 months. Indwelling catheter exchange results in an immediate reduction in urine leukocytes and bacteriuria.