Dialysis fluid

Dialysis solution is infused into the patient’s abdominal cavity through a permanently implanted tube. The solution remains there for several hours, picking up waste from the blood stream, is allowed to flow out and the process is repeated. The extent of handling makes the likelihood of infection quite high and a large variety of microorganisms may infect the dialysis fluid.

Setup NOTE No more than one dialysis fluid per patient should be processed every other day. If a bag of cloudy fluid is received after a clean one is processed, culture and sensitivity is always done.

A portion of the fluid should be sent to Hematology for cell count if requested.

Examine the bags noting the colour and turbidity of the fluid. Record the observations.

Shake bag well to mix. Working at the sink, disinfect the port with 70% ethanol and let stand for several minutes. Open clamp and run off some of the dialysate.

Fill a red top vacutainer tube with approximately 5 mL of dialysate and send to Hematology for cell count if requested.

Fill three 50 mL sterile plastic centrifuge tubes with dialysate. Centrifuge two of the tubes (3500 rpm x 20 minutes). Store the third centrifuge tube at 4°C for at least 7 days. Discard the bag after collecting dialysate.

Decant the supernatant leaving approximately 10 mL in each tube. Vortex well to re-suspend the sediment and pool the two tubes into one. Prepare Gram smear and inoculate culture media as outlined below.

Direct Examination

If specimen is cloudy: Gram stain
If specimen is clear: Gram stain is not performed

Culture

If the specimen is clear inoculate an aerobic and an anaerobic blood culture bottle with 8-9 mLs of specimen and process with usual blood culture protocol. Plates are not inoculated.

If the specimen is cloudy inoculate blood culture bottles and inoculate:

Media Incubation
Blood Agar (BA) CO2, 35°C x 4 days
Chocolate Agar (CHOC) CO2, 35°C x 4 days
MacConkey Agar (MAC) O2, 35°C x 4 days

Interpretation Examine the BA, MAC and CHOC daily for up to 4 days incubation. Identify all isolates.

Identify all isolates from blood culture bottles.

Reporting

Gram stain

Report the presence or absence of organisms and WBCs. Do not quantitate.

Culture

Negative Report
“No growth”

Positive Report
Report all isolates with appropriate susceptibilities. Do not quantitate except if it is from the fluid medium only – add comment “From broth culture only, indicative of small numbers and/or contamination.”

Telephone all positive Gram stain and culture results to ward/ordering physician.

References P.R. Murray, E.J. Baron, M.A. Pfaller, R.H. Yolken. 2003. Manual of Clinical Microbiology, 8th ed. ASM Press, Washington, D.C.

H.D. Izenberg. 2003. Blood Cultures-General Detection and Interpretation, p.3.4.1.1-3.4.1.19 In Clinical Microbiology Procedures Handbook, 2nd ed. Vol.1 ASM Press, Washington, D.C.