Predominance of Gram-Negative Pathogens and Treatment Complexity in Peritoneal Dialysis-Associated Peritonitis: A...

Background: Peritoneal dialysis-associated peritonitis (PDAP) remains a major complication of peritoneal dialysis and an important cause of technique failure. Increasing evidence suggests marked inter-center variability in PDAP microbiology, with a growing contribution of Gram-negative pathogens in some settings. Methods: We performed a single-center, retrospective observational study of adult peritoneal dialysis patients with PDAP treated between January 2020 and December 2024. Episodes were defined according to International Society for Peritoneal Dialysis criteria. Clinical, microbiological, and antimicrobial treatment data were analyzed, with particular focus on relapsing peritonitis and treatment complexity. Results: Thirty-three patients were included (median age 59 years; 51.5% male). Gram-negative organisms were the most frequent causative agents (48.5%), followed by Gram-positive bacteria (21.2%), fungal pathogens (6.1%), and culture-negative episodes (6.1%). Relapsing or recurrent peritonitis occurred in 12.1% of cases and was significantly associated with increased antimicrobial treatment complexity, with all relapsing episodes requiring three or more antimicrobial agents (p = 0.02). Conclusions: Gram-negative pathogens predominated in this single-center PDAP cohort and showed trends toward greater antimicrobial treatment complexity and a higher burden of relapsing episodes; however, these findings should be interpreted cautiously due to the limited sample size and lack of statistical significance. These findings nevertheless support the need for center-specific microbiological surveillance and individualized management strategies in peritoneal dialysis-associated peritonitis.