Differing outcomes of gram-positive and gram-negative peritonitis

Peritonitis remains the leading cause of patient dropout from continuous peritoneal dialysis (CPD) therapy. Few studies have compared patient morbidity, mortality, and outcome for patients undergoing CPD who develop gram-positive and gram-negative peritonitis. We retrospectively reviewed the charts of patients who developed either gram-positive or gram-negative peritonitis between January 1, 1993, and December 31, 1995. Three hundred seventy-five patients who developed 415 episodes of gram-positive and gram-negative peritonitis were maintained on CPD therapy during this time period. There was no difference in age, race, and sex between patients who developed gram-positive or gram-negative peritonitis. More patients with diabetes developed gram-negative peritonitis than gram-positive peritonitis (53% v 40%, respectively; P < 0.05). Coagulase-negative staphylococcal species accounted for 47% of all gram-positive episodes, whereas Klebsiella organisms, Escherichia coli, and Enterobacter organisms accounted for 63% of all gram-negative episodes. Significantly more patients who developed gram-positive peritonitis continued CPD therapy 2 weeks and 6 months after the onset of peritonitis than patients who developed gram-negative peritonitis (97% v 73%; P < 0.05 at 2 weeks and 81% v 58% at 6 months; P < 0.05, respectively). Nine percent of the patients who developed gram-positive peritonitis died within 6 months after the onset of peritonitis, whereas 21% of the patients who developed gram-negative peritonitis died (P < 0.05). Patients who developed gram-negative peritonitis were significantly more likely to require hospitalization than patients who developed gram-positive peritonitis (74% v 24%; P < 0.001). More patients with gram-negative peritonitis required peritoneal catheter removal than patients with gram-positive peritonitis (18% v 4%; P < 0.001). Thirty-two percent of the patients who developed gram-positive peritonitis re-developed an episode of peritonitis with the same organism compared with only 9% of the patients who developed gram-negative peritonitis. Furthermore, peritonitis recurrence with the same organism within 6 months after the initial episode was noted in 60% of the patients with peritonitis caused by Staphylococcus aureus compared with 24% of patients with peritonitis caused by other gram-positive organisms (P < 0.05). We conclude that the outcomes of gram-positive and gram-negative peritonitis are different. When rates of peritonitis are used to predict outcome, it appears that gram-positive and gram-negative peritonitis rates need to be examined separately.