Primary kidney disease was classified into 9 main categories according to the codes of the European Renal Association - European Dialysis and Transplant Association. Peritonitis in PD was defined as a peritoneal dialysate effluent containing >100 white blood cells/mL, of which >50% were polymorphonuclear leukocytes. Patients with two or more pathogens isolated from the cultures in a peritonitis episode were considered to have polymicrobial peritonitis. A relapse of peritonitis was defined when the same organism or a culture-negative peritonitis episode was identified within 4 weeks of completing appropriate antibiotic therapy for a previous episode.