Microbiology and outcomes of polymicrobial peritonitis associated with peritoneal dialysis: a register-based cohort study from the French Language Peritoneal Dialysis Registry.

BACKGROUND: Previous studies have reported that polymicrobial peritonitis in peritoneal dialysis (PD) is associated with poor outcomes, but recent data from European cohorts are scarce. METHODS: We included from the French Language Peritoneal Dialysis Registry all patients ≥18 years of age who started PD between January 2014 and November 2020. We compared microbiology and patient characteristics associated with mono- and polymicrobial peritonitis. We assessed patient outcomes after a first polymicrobial peritonitis using survival analysis with competing events. We differentiated microorganisms isolated from dialysis effluent as enteric or non-enteric pathogens. RESULTS: A total of 8848 patients contributed 13 023 patient-years of follow-up and 3348 culture-positive peritonitis episodes, including 251 polymicrobial ones. This corresponded to rates of 0.32 and 0.02 episodes/patient-year, respectively. For most patients (72%) who experienced polymicrobial peritonitis, this was their first peritonitis episode. Enteric pathogens were more frequently isolated in polymicrobial than in monomicrobial peritonitis (57 versus 44%; P < .001). In both cases of peritonitis with and without enteric pathogens, the polymicrobial versus monomicrobial character of the peritonitis was not associated with mortality in patients who did not switch to haemodialysis {adjusted cause-specific hazard ratio [acsHR] 1.2 [95% confidence interval (CI) 0.3-5.0], P = .78 and 1.1 [95% CI 0.7-1.8], P = .73, respectively}. However, the risks of death and switch to haemodialysis were higher for monomicrobial peritonitis with enteric pathogens compared with those without [acsHR 1.3 (95% CI 1.1-1.7), P = .02 and 1.9 (95% CI 1.5-2.4), P < .0001, respectively]. CONCLUSION: Isolation of enteric pathogens, rather than the polymicrobial character of the peritonitis, is associated with poorer outcomes.