Evaluation of intraperitoneal vancomycin in peritoneal dialysis-associated peritonitis

Background: Intraperitoneal (IP) vancomycin is recommended as one of the treatment options for gram-positive coverage in the management of peritoneal dialysis (PD)-associated peritonitis. There is a lack of literature supporting the optimal dose and approach to vancomycin therapeutic drug-level monitoring. Methods: A retrospective chart review was conducted using the BC Renal Agency PROMIS Database and our hospital records from 1 June 2011 to 1 July 2019. Adult patients with PD-associated peritonitis who received IP vancomycin and had at least one serum vancomycin level drawn were included. All patients received a loading dose of 30 mg/kg, which was repeated every 3-5 days depending on PD modality. Serum vancomycin levels were drawn prior to the second vancomycin dose, then at the discretion of the prescriber. The primary end point was the rate of therapeutic serum vancomycin levels >= 15 mg/L. Results: Twenty-three episodes of PD-associated peritonitis in 20 patients met the eligibility criteria. Only 15/23 serum vancomycin levels were drawn appropriately after the first dose. Sixty per cent of these levels were subtherapeutic at <15 mg/L. All subsequent serum vancomycin levels were above the therapeutic target. Most peritonitis episodes (78%) achieved resolution of infection. Residual kidney function was not significantly correlated with serum vancomycin levels (p = 0.19). Conclusions: An IP vancomycin regimen of 30 mg/kg every 3-5 days resulted in subtherapeutic serum vancomycin levels in most patients following the loading dose but therapeutic levels thereafter. A large percentage of vancomycin levels were drawn inappropriately due to misalignment of outpatient follow-up visits and timing of blood work.