Morphometric and biological characterization of biofilm in tunneled hemodialysis catheters.
BACKGROUND
Bacterial biofilm formation on hemodialysis tunneled cuffed catheters is under-recognized. We studied biofilm characteristics in patients with and without catheter-related bloodstream infection, accounting for catheter locking solution (citrate 4% or heparin 1:1,000).


METHODS
Prospective observational study.


METHODS
30 HD patients for whom the tunneled cuffed catheter was removed for either noninfectious reasons (n = 19) or bacteremia (n = 11).


METHODS
Bacteremia and catheter locking solution.


METHODS
Bacteria density in the biofilm, catheter luminal surface covered by biofilm, biofilm thickness, and exopolysaccharide content.


RESULTS
Biofilm was present in all catheters. Overall, bacteria density, catheter surface coverage, biofilm thickness, and exopolysaccharide content were significantly higher in catheters from patients with bacteremia (5.3 [95% CI, 3.4-7.2] colony-forming unit [CFU]/mL; 47% [95% CI, 34%-60%]; 41 [95% CI, 26-55] μm; and 29.4% [95% CI, 20.1%-38.6%], respectively) than from patients without bacteremia (3.7 [95% CI, 3.6-3.8] CFU/mL; 17% [95% CI, 16%-19%]; 8.6 [95% CI, 7.3-9.8] μm; and 5.3% [95% CI, 3.7%-6.8%], respectively). However, all biofilm parameters were lower in catheters from patients with bacteremia when citrate was used as locking agent. Furthermore, bacteria density (0.08 [95% CI, 0.02-0.13] CFU/mL/3 cm), biofilm thickness (1.4 [95% CI, 0.8-2.1] μm/3 cm), and surface coverage (2.2% [95% CI, 1.8%-2.7%]/3 cm) decreased across the length of the catheter from tip to hub.


CONCLUSIONS
Observational study design, small numbers of patients, use of prevalent catheters.


CONCLUSIONS
Biofilms are present in all tunneled cuffed catheters. However, the extent of the biofilm varied by the presence of bacteremia and type of locking solution. This method could be used to explore preventative measures.
Division of Nephrology, University of Calgary, Calgary, Alberta, Canada.
Steven M
SM
Jones
Pietro
P
Ravani
Brenda R
BR
Hemmelgarn
Daniel
D
Muruve
Jennifer M
JM
Macrae
D000368:Aged; D016470:Bacteremia / Q000175:diagnosis / Q000382:microbiology*; D018441:Biofilms / Q000254:growth & development*; D002408:Catheters, Indwelling / Q000009:adverse effects / Q000382:microbiology*; D015169:Colony Count, Microbial; D005260:Female; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000175:diagnosis / Q000382:microbiology*; D006435:Renal Dialysis