Plasma and Peritoneal Dialysate Levels During Daptomycin Therapy for Peritonitis

Treatment of peritoneal dialysis–related bacterial infection has become more challenging because of the increasing antibiotic resistance of Gram-positive pathogens.1 Here, we report blood and peritoneal dialysis fluid levels of the novel cyclic lipopeptide antibiotic daptomycin in an 73-year-old anuric man on peritoneal dialysis therapy with recurrent peritonitis. Daptomycin exerts its potent bactericidal activity against Gram-positive pathogens by means of rapid cell depolarization and has shown specific antibiofilm actitivity in vitro.2, 3 In patients with normal kidney function, the recommended dose schedule is once daily intravenously at 4 to 6 mg/kg of body weight. Daptomycin is excreted mainly by the kidney (∼78%); therefore, a primarily extrapolated dose recommendation suggests administration every other day in patients with glomerular filtration rate less than 30 mL/min (<0.5 mL/s).4

In our patient, peritonitis was recurrent and caused by a biofilm-producing Gram-positive Staphylococcus capitis pathogen. The initial empiric antibiotic regimen was switched to 5 mg of daptomycin intravenously every 48 hours. In dialysate, daptomycin concentrations greater than 1 mg/L (the minimum inhibitory concentration for most Gram-positive pathogens4, 5) were rapidly achieved (Fig 1A). In plasma, daptomycin steady-state trough levels were 8 to 10 mg/L (Fig 1B), with a mean plasma elimination half-life of 22.4 hours. Of the amount administered, 11% was removed by means of peritoneal dialysis (19.8 ± 1.94 mg/d, yielding an extrapolated plasma clearance of 0.3 L/h). Removal of the highly protein-bound daptomycin (>90%) may have been facilitated by a low plasma albumin level in the patient (2.1 g/dL [21 g/L]). We suggest that daptomycin can be used for treatment of peritoneal dialysis–associated peritonitis.

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Figure 1. (A) Peritoneal dialysis fluid and (B) blood trough concentrations of daptomycin in a patient with Gram-positive peritoneal dialysis–associated peritonitis. Daptomycin was given intravenously at a dose of 5 mg/kg body weight every 48 hours (open arrows). Peritoneal dialysis fluid was collected at the end of 3 daytime 4-hour periods (2 L Physioneal® 2.27% each) and 1 overnight 12-hour dwell time (2 L Extraneal® 7.5% per day). Daptomycin concentrations were measured by using high-performance liquid chromatography.6 The patient's hospital discharge is indicated.