A preliminary survey of bacterial contamination of the dialysate circuit in continuous veno-venous hemodialysis.
OBJECTIVE
The problem of dialysate bacterial contamination has not been defined in continuous renal replacement therapy. We assessed the bacterial integrity of source bicarbonate dialysate (study 1) and the continuous veno-venous HD (CVVHD) bicarbonate dialysate circuit (study 2).


METHODS
Study 1: 50 ml dialysate were collected from 41 bags randomly selected from 150 consecutively made dialysate bags, immediately after manufacture or after 24, 48 or 72 h. Study 2: 10 ml dialysate were drawn from 4 sample points ranged along the dialysate circuit in 18 therapies (mean duration 119.5 +/- 72.0 h). All points were sampled at therapy start then daily, bar the proximal point which was sampled after each dialysate bag change. All dialysate samples underwent Gram stain and aerobic/anaerobic culture. Samples over 10 ml were cultured after centrifugation (15 min, 4,000 rpm). A disseminated contamination (DC) involved > or = 1 sample point at a time and/or was sustained over time.


RESULTS
Study 1: One bag was culture-positive (staphylococcal/diphtheroid growths; 48-h sample). Study 2: Six DCs developed in 6 therapies (1 at therapy end, 5 sustained to therapy end (duration 57.25 +/- 45.95 h), 5 with Gram-negative bacilli, all involving reported growths of > or = 1,000 cfu). Dialyzer-inclusive dialysate circuit changes were more frequent in non-DC therapies (change rate: DC, 0.08 +/- 0.12/day, non-DC, 0.34 +/- 0.23, p = 0.02, permutation tests with general scores) but did not entirely prevent DC or alter it once underway.


CONCLUSIONS
Sustained bacterial contamination of bicarbonate-based CVVHD is common and could relate to the completeness of dialysate circuit change. The importance of technique and regular quality control is highlighted.
Kanagasundaram
N S
NS
Department of Hypertension/Nephrology, Section of Dialysis and Extracorporeal Therapy, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA. surenkan@yahoo.com
Larive
A B
AB
Paganini
E P
EP
D001407:Bacillus / Q000302:isolation & purification; D001639:Bicarbonates / Q000302:isolation & purification*; D002021:Buffers; D015314:Dialysis Solutions / Q000302:isolation & purification*; D004866:Equipment Contamination; D006095:Gram-Positive Cocci / Q000302:isolation & purification; D019538:Health Care Surveys; D006440:Hemofiltration; D006801:Humans; D007260:Infusion Pumps / Q000382:microbiology*; D007674:Kidney Diseases / Q000382:microbiology / Q000628:therapy*; D011786:Quality Control; D013997:Time Factors
D001639:Bicarbonates; D002021:Buffers; D015314:Dialysis Solutions