Laboratory diagnosis of peritonitis in patients treated with continuous ambulatory peritoneal dialysis

Area of Science:

• Clinical Microbiology
• Nephrology
• Infectious Diseases

Background:

• Patients on continuous ambulatory peritoneal dialysis (CAPD) face a high risk of microbial invasion in the peritoneal cavity.
• Prompt and accurate microbiological diagnosis of peritonitis is critical for effective patient management.
• Aseptic peritonitis is frequently diagnosed, complicating microbiological assessments with small dialysate volumes.

Purpose of the Study:

• To enumerate microorganisms commonly found in clinical peritonitis cases associated with CAPD.
• To compare the diagnostic efficacy of various laboratory culture systems for peritonitis.
• To determine the optimal sample volume for reliable microbiological diagnosis of CAPD-related peritonitis.

Main Methods:

• Comparison of four qualitative culture systems: low (1 ml) and high (10 ml) volume broth inoculations, centrifugation (10 ml) with sediment culture, and filtration (≤100 ml) with filter culture.
• Utilized pour plate and drop plate methods for quantitative microbial enumeration.
• Analyzed dialysate samples from patients experiencing peritonitis.

Main Results:

• Culturing 10 ml of dialysate fluid demonstrated comparable efficacy to culturing larger volumes obtained via filtration.
• Low volume (1 ml) cultures yielded a significantly lower proportion of positive results.
• The study observed low numbers of viable microorganisms in dialysate from peritonitis patients.

Conclusions:

• A minimum of 10 ml of peritoneal dialysis fluid should be cultured to reliably detect microorganisms in cases of peritonitis.
• Larger volume cultures (e.g., via filtration) and 10 ml cultures are effective, while 1 ml cultures are insufficient.
• Optimizing culture volume is essential for accurate diagnosis and management of CAPD-associated peritonitis.