Coagulase-negative staphylococcal peritonitis in Australian peritoneal dialysis patients: predictors, treatment and outcomes in 936 cases

Abstract

Coagulase-negative staphylococcal (CNS) peritonitis is the most common cause of peritoneal dialysis (PD)-associated peritonitis. Previous reports of this important condition have been sparse and generally limited to single-centre studies. The frequency, predictors, treatment and clinical outcomes of CNS peritonitis were examined by multivariate logistic regression and multilevel Poisson regression in all adult PD patients in Australia between 2003 and 2006. A total of 936 episodes of CNS peritonitis (constituting 26% of all peritonitis episodes) occurred in 620 individuals. The observed rate of CNS peritonitis was 0.16 episodes per patient-year. Lower rates of CNS peritonitis were independently predicted by Asian racial origin (adjusted odds ratio [OR], 0.52; 95% CI, 0.35-0.79), renovascular nephrosclerosis (OR, 0.40; 95% CI, 0.18-0.86), early referral to a renal unit prior to dialysis commencement (OR, 0.38; 95% CI, 0.19-0.79) and treatment with automated PD at any time during the PD career (OR, 0.79; 95% CI, 0.66-0.96). The majority of CNS peritonitis episodes were initially treated with intraperitoneal vancomycin or cephazolin in combination with gentamicin. This regimen was changed in 533 (57%) individuals after a median period of 3 days, most commonly to vancomycin monotherapy. The median total antibiotic course duration was 14 days. Compared with other forms of peritonitis, CNS episodes were significantly more likely to be cured by antibiotics alone (76 vs 64%, P < 0.001) and less likely to be complicated by hospitalization (61 vs 73%, P < 0.001), catheter removal (10 vs 26%, P < 0.001), temporary haemodialysis (2 vs 5%, P < 0.001), permanent haemodialysis transfer (9 vs 21%, P < 0.001) and death (1.0 vs 2.7%, P = 0.002). CNS peritonitis was also associated with a shorter duration of hospitalization, a longer time to catheter removal and a shorter duration of temporary haemodialysis. Catheter removal and permanent haemodialysis transfer were independently predicted by polymicrobial peritonitis and initial empiric administration of vancomycin (compared with cephalosporins). CNS peritonitis was associated with a higher relapse rate (17 vs 13%, P = 0.003) and relapsed CNS peritonitis was associated with a higher catheter removal rate (22 vs 7%, P < 0.001). Repeat peritonitis occurred in 194 (31%) individuals and the highest risk was in the second month after completion of antibiotic treatment for CNS peritonitis (OR, 1.87; 95% CI, 1.39-2.51 compared with >2 months). CNS peritonitis is a common complication with a relatively benign outcome compared with other forms of PD-associated peritonitis. Relapsed and repeat peritonitis are relatively common and are associated with worse outcomes.