Polymicrobial peritonitis in peritoneal dialysis patients in Australia: predictors, treatment, and outcomes.
BACKGROUND
The study aim was to examine the frequency, predictors, treatment, and clinical outcomes of peritoneal dialysis-associated polymicrobial peritonitis.


STUDY DESIGN
Observational cohort study using ANZDATA (The Australia and New Zealand Dialysis and Transplant Registry) data.


SETTING & PARTICIPANTS
All Australian peritoneal dialysis patients between October 2003 and December 2006.


PREDICTORS
Age, sex, race, body mass index, baseline renal function, late referral, kidney disease, smoking status, comorbidity, peritoneal permeability, center, state, organisms, and antibiotic regimen.


OUTCOMES & MEASUREMENTS
Polymicrobial peritonitis occurrence, relapse, hospitalization, catheter removal, hemodialysis transfer, and death.


RESULTS
359 episodes of polymicrobial peritonitis occurred in 324 individuals, representing 10% of all peritonitis episodes during 6,002 patient-years. The organisms isolated included mixed Gram-positive and Gram-negative organisms (41%), pure Gram-negative organisms (22%), pure Gram-positive organisms (25%), and mixed bacteria and fungi (13%). There were no significant independent predictors of polymicrobial peritonitis except for the presence of chronic lung disease. Compared with single-organism infections, polymicrobial peritonitis was associated with higher rates of hospitalization (83% vs 68%; P < 0.001), catheter removal (43% vs 19%; P < 0.001), permanent hemodialysis transfer (38% vs 15%; P < 0.001), and death (4% vs 2%; P = 0.03). Isolation of fungus or Gram-negative bacteria was the primary predictor of adverse clinical outcomes. Pure Gram-positive peritonitis had the best clinical outcomes. Patients who had their catheters removed >1 week after polymicrobial peritonitis onset were significantly more likely to be permanently transferred to hemodialysis therapy than those who had earlier catheter removal (92% vs 81%; P = 0.05).


LIMITATIONS
Limited covariate adjustment. Residual confounding and coding bias could not be excluded.


CONCLUSIONS
Polymicrobial peritonitis can be treated successfully using antibiotics alone without catheter removal in most cases, particularly when only Gram-positive organisms are isolated. Isolation of Gram-negative bacteria (with or without Gram-positive bacteria) or fungi carries a worse prognosis and generally should be treated with early catheter removal and appropriate antimicrobial therapy.