Continuous infusion vancomycin for treatment of methicillin-resistant Staphylococcus aureus in cystic fibrosis patients.

OBJECTIVE: To report 3 cases of methicillin-resistant Staphylococcus aureus (MRSA) in pediatric patients with cystic fibrosis (CF), all of whom had inadequate serum concentrations of vancomycin with conventional intermittent dosing and who achieved therapeutic serum concentrations with continuous infusions of vancomycin. CASE
SUMMARY: In the first case, a 3-year-old patient failed to achieve therapeutic vancomycin trough concentrations despite 2 dose adjustments up to 19 mg/kg every 6 hours. A continuous infusion was initiated and a therapeutic steady-state level was obtained. The remaining case reports describe 2 patients who were readmitted to the hospital after having received intermittent dosing as outpatients. Continuous infusions were started upon readmission, and therapeutic serum concentrations were achieved in both patients. DISCUSSION: MRSA is a common pathogen in patients with CF. Intravenous vancomycin, a time-dependent antibiotic that is extensively eliminated by the kidneys, is frequently used to treat MRSA infections. Serum trough concentrations of 15-20 mg/L are considered therapeutic, but these levels are difficult to achieve in patients with CF because of increased renal clearance. Continuous infusions of vancomycin were successfully used in the patients described here and resulted in decreased total daily doses of vancomycin, clinical improvement, and no evidence of nephrotoxicity.
CONCLUSIONS: Although more extensive studies are necessary, the cases presented here suggest that continuous infusion vancomycin is a safe and convenient therapy for MRSA infections.