Challenging the current treatment paradigm for methicillin-resistant Staphylococcus epidermidis peritonitis in peritoneal dialysis patients.

Objectives: To analyze clinical outcomes of Staphylococcus epidermidis peritoneal dialysis peritonitis before and after an interventional switch from a vancomycin/ tobramycin to a cefazolin/tobramycin regimen for empiric treatment. To examine risk factors associated with clinical failure.

Design: A retrospective study.

Setting: A peritoneal dialysis program within a university-affiliated tertiary-care hospital.

Patients: 93 episodes of S. epidermidis peritonitis over a 6-year period.

Interventions: Clinical responses were compared between treatments using chi-square or Fisher's exact test. Univariate and multivariate analyses were used to identify significant risk factors for clinical failure.

Measurements And Main Results: There was no difference in the overall response rates observed with vancomycin (40/49; 81.6%) and cefazolin (23/29; 79.3%) regimens for episodes of S. epidermidis peritonitis. Furthermore, the presence of methicillin resistance in 63 of 93 cases (67.7%) had no influence on clinical outcome, with response rates of 83.9% (26/31) and 82.4% (14/17) for empiric vancomycin and cefazolin regimens, respectively. Tobramycin therapy of less than 2 days was an independent risk factor for clinical failure in multivariate logistic regression analysis (odds ratio 4.44, 95% confidence interval 1.28 - 15.48; p = 0.02).

Conclusions: Empiric treatment with intraperitoneal cefazolin was as effective as vancomycin for S. epiderimidis peritonitis despite a high prevalence of methicillin resistance. Tobramycin therapy of less than 2 days was strongly associated with treatment failure.