Multicentre registry data analysis comparing outcomes of culture-negative peritonitis and different subtypes of culture-positive peritonitis in peritoneal dialysis patients.

Background: The outcomes of culture-negative peritonitis in peritoneal dialysis (PD) patients have been reported to be superior to those of culture-positive peritonitis. The current study aimed to examine whether this observation also applied to different subtypes of culture-positive peritonitis. Methods: This multicentre registry study included all episodes of peritonitis in adult PD patients in Australia between 2004 and 2014. The primary outcome was medical cure. Secondary outcomes were catheter removal, hemodialysis transfer, relapsing/recurrent peritonitis and peritonitis-related death. These outcomes were analyzed using mixed effects logistic regression. Results: Overall, 11,122 episodes of peritonitis occurring in 5367 patients were included. A total of 1760 (16%) episodes were culture-negative, of which 77% were medically cured. Compared with culture-negative peritonitis, the odds of medical cure were lower in peritonitis caused by Staphylococcus aureus (adjusted odds ratio (OR) 0.62, 95% confidence interval (CI) 0.52-0.73), Pseudomonas species (OR 0.20, 95% CI 0.16-0.26), other gram-negative organisms (OR 0.48, 95% CI 0.41-0.56), polymicrobial organisms (OR 0.30, 95% CI 0.25-0.35), fungi (OR 0.02, 95% CI 0.01-0.03), and other organisms (OR 0.61, 95% CI 0.49-0.76), while the odds were similar in other (non-staphylococcal) gram-positive organisms (OR 1.11, 95% CI 0.97-1.28). Similar results were observed for catheter removal and hemodialysis transfer. Compared with culture-negative peritonitis, peritonitis-related mortality was significantly higher in culture-positive peritonitis except that due to other gram-positive organisms. There was no difference in the odds of relapsing/recurrent peritonitis between culture-negative and culture-positive peritonitis. Conclusion: Culture-negative peritonitis had superior outcomes compared to culture-positive peritonitis except for non-staphylococcal gram-positive peritonitis.