Peritoneal Dialysis Peritonitis
Peritoneal dialysis (PD)-associated peritonitis occurs in approximately 30% to 40% of patients during their course of PD treatment and develops when infectious organisms gain access to the peritoneal cavity. Infection can occur due to a breach in aseptic technique that introduces infectious organisms in the PD catheter, infection with skin organisms that migrate down the catheter tunnel into the peritoneal cavity, translocation of organisms from the gastrointestinal or genitourinary tract, or, in less than 1% of cases, hematogenous spread to the peritoneal cavity. After organisms enter the peritoneal cavity, polymorphonuclear leukocytes (PMNs) induce an inflammatory cascade, causing abdominal pain and cloudy dialysate.
PD-associated peritonitis is diagnosed in patients who meet at least 2 of the following 3 criteria: (1) clinical features consistent with peritonitis such as abdominal pain and/or cloudy PD fluid), (2) PD fluid white blood cell (WBC) count greater than or equal to 100 cells/μL with greater than or equal to 50% PMNs in dialysate that has dwelled in the abdomen for at least 2 hours; and (3) positive dialysate fluid culture result.
A PD fluid WBC count of at least 100 cells/μL has a sensitivity of 80% and a specificity of 89% for the diagnosis of PD-associated peritonitis. PD fluid predominance of PMNs (≥50% of WBC) has a specificity of 97% for PD-associated peritonitis. PD effluent Gram stain results are positive in less than 10% of cases of suspected PD-associated peritonitis but may help in the early identification of yeast or fungal peritonitis. PD fluid culture results are positive in approximately 72% to 86% of patients with PD-associated peritonitis. Negative PD fluid culture results are typically due to inappropriate sample collection or processing, but may rarely be due to mycobacteria, filamentous fungi, or other fastidious organisms. A peritoneal fluid PMN-to-lymphocyte ratio less than 15 can help distinguish mycobacterial infection from bacterial peritonitis (sensitivity, 81%; specificity, 70%; positive predictive value, 97%). If PD fluid dwells in the abdomen for more than 15 hours, the PD fluid WBC count may exceed 100 cells/μL in the absence of peritonitis but is macrophage predominant.
PD-associated peritonitis is typically caused by bacteria such as Staphylococcus, Streptococcus, Enterococcus, Corynebacterium, E. coli, Klebsiella, and Pseudomonas. Cloudy PD fluid can occur in several conditions other than infectious peritonitis.
Reference
Perl J. et al. Peritoneal Fluid Analysis in Peritoneal Dialysis–Associated Peritonitis, JAMA, published online November 10, 2022. doi:10.1001/jama.2022.21289
