Principles of Accurate Peritoneal Dialysis Effluent
Sampling and Culturing
Identifying appropriate antibiotic therapy is dependent on accurate specimen collection and microbiological diagnosis of peritonitis.
Key Points for Specimen Processing:
- Culture should be obtained as early as possible
- The first bag of cloudy solution is the best specimen, as the probability of a positive diagnostic culture is the greatest
- Patients or PD staff should send the first cloudy bag or an aliquot thereof to the laboratory as quickly as possible
- While delay of several hours from time of collection to time of culture does not decrease accuracy of bacteriological diagnosis, it is preferable to expedite this process
- As large a volume (20 to 100 mL) as possible should be cultured or concentrated to maximize bacterial recovery rates
- Draw fluid from medication port
- Blood culture techniques are considered most optimal
- Inject fluid into standard blood culture medium (5–10 mLs required per bottle)
- The collection and processing of specimens require meticulous care in order to avoid contamination of the fluid
- Laboratory should be notified of specimens obtained from patients receiving antibiotic therapy, as they may require special handling
- Identification and sensitivity testing should be expedited to facilitate initiation of specific antibiotic therapy
Sterile or Culture-negative Peritonitis:
- Incidence of sterile peritonitis varies from 2% to 20% and is more common when the laboratory facility does not have experience in processing peritoneal dialysis effluent
- Other factors contributing to a high incidence of sterile peritonitis include:
-
- Insufficient culture sample volume
- Causative organism difficult to culture
- Causative organism requiring specialized culture media (i.e., mycobacteria)
- Patient may not have informed PD center of current antibiotic treatment
- Patient’s signs and symptoms related to other medical condition (i.e., pancreatitis)
References used in this Appendix section
- Li PK, Szeto CC, Piraino B, et al. Peritoneal dialysis-related infectious recommendations: 2010 update. Perit Dial Int 2010;30(4):393–423.
- Li PKT, Szeto CC, Piraino B, et al. ISPD peritonitis recommendations: 2016 update on prevention and treatment. Perit Dial Int 2016;36:481–508.