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Method for studying development of colonization and infection of dialysis catheters
G H Khaled1, F O Finkelstein, H B Carey
1Department of Laboratory Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Abstract:
Microbial colonization and infection of dialysis catheters is the major cause of catheter failure. The present study aimed to develop a method to permit the study of microbial biofilm formation and antibiotic prophylaxis and therapy. Standard silicon rubber and silver-impregnated catheters were sectioned into 1 mm slices and placed into 1-cm x 2-cm culture slide chambers. Fresh clinical isolates were obtained from infected patients and suspended in concentrations of 10(3), 10(6), and 10(9) colony forming units (CFU) per milliliter in a variety of liquid suspending culture media, which included serum protein constituents. Antibiotics could be added to the suspending fluid to determine prophylactic activity, or at any time thereafter to determine therapeutic activity. The catheter sections were incubated with the microbial challenge for 6 hours, 12 hours, 24 hours, and 48 hours and then washed in flowing distilled water to remove unattached biofilm. They were then stained with acridine orange, which fluoresces microbial DNA, and were examined by confocal scanning laser microscopy. Biofilm formation, representing colonization and infection, were quantified by comparing the fluorescent pixel analysis of the uninoculated control with the challenged catheter. The method was reproducible and permitted quantitative analysis. Standard silicon rubber catheters demonstrated greater biofilm formation than silver-impregnated catheters. The method examines the factors involved in microbial colonization and infection, and in antibiotic prophylaxis and therapy.
Insights
A new method quantifies microbial biofilm formation on dialysis catheters, revealing silver-impregnated versions reduce colonization compared to standard silicon rubber. This aids studying catheter infection and antibiotic effectiveness.
Area of Science:
- Biomedical Engineering
- Microbiology
- Infectious Diseases
Background:
- Dialysis catheter failure is frequently caused by microbial colonization and infection.
- Developing effective strategies for preventing and treating these infections is crucial for patient outcomes.
Purpose of the Study:
- To develop a reproducible method for studying microbial biofilm formation on dialysis catheters.
- To quantitatively assess biofilm formation and evaluate antibiotic prophylaxis and therapy.
- To compare biofilm formation on standard silicon rubber versus silver-impregnated catheters.
Main Methods:
- Dialysis catheter sections were challenged with clinical microbial isolates at varying concentrations.
- Biofilm formation was quantified using confocal scanning laser microscopy after acridine orange staining.
- Antibiotics were introduced to assess prophylactic and therapeutic activities.
Main Results:
- The developed method provided reproducible, quantitative analysis of biofilm formation.
- Standard silicon rubber catheters showed significantly greater biofilm formation than silver-impregnated catheters.
- The method allowed for the examination of factors influencing microbial colonization and the efficacy of antibiotic treatments.
Conclusions:
- A novel, quantitative method for studying dialysis catheter microbial colonization and biofilm formation has been established.
- Silver-impregnated catheters demonstrate reduced biofilm formation compared to standard silicon rubber catheters.
- This methodology can be utilized to investigate microbial infection dynamics and optimize antibiotic strategies for dialysis catheters.
