1543. Ceftaroline Model-based Dose Individualization in an Infant with Kidney Disease and Mediastinitis

BACKGROUND: Options for the treatment of infections caused by resistant gram-positive bacteria are limited in children with kidney disease. Ceftaroline (CFD) may be an attractive option but dosing recommendations are not available for children with renal dysfunction. We present a case of pharmacokinetics (PK) model-based individualization of CFD in an infant with kidney disease and mediastinitis. A 5-week-old infant with a hypoplastic left side of the heart developed mediastinitis following a Norwood and BT shunt. Blood and chest washout cultures grew S. epidermidis. Vancomycin therapy led to acute kidney injury (AKI) (eGFR ~15mL/minute) and therefore, CFD was initiated at 8 mg/kg every 12 hours. The model-based clinical service was consulted to assist with dosing. METHODS: Plasma levels were drawn on day 2 and 10 of CFD. CFD concentrations were determined by HPLC. The pharmacodynamic (PD) target used the MIC of the isolate, 1 µg/mL, and assumed drug diffusion into the mediastinum at 20% of plasma. The PD target was ƒT>MIC at 100%. Individual PK parameters were estimated using Bayesian estimation with MWPharm++ (Mediware, the Netherlands). RESULTS: CFD dosing of 8 mg/kg every 12 hours resulted in concentrations well above the target. The trough level was 10 times higher than levels seen in clinical trials. Repeat levels were checked on day 10 due to improved renal function (eGFR 30 mL/minute) and changes in volume status. Changes in both clearance and volume were noted. ƒT>MIC was maintained 100% during dosing intervals. We dose optimized CFD to achieve the target while minimizing potential toxicity with long-term use. A new dosing regimen, 5.4 mg/kg every 8 hours, was started on day 12 and continued for 6 weeks. CONCLUSION: This is the first case report of CFD use in a child with AKI. Though initial dosing resulted in high concentrations, no adverse effects were noted. Successful treatment was completed with a final dosing regimen of 5.3 mg/kg every 8 hours, below the recommended 8 mg/kg every 8 hours. Lower dosing was needed to decrease high drug exposure due to the decreased clearance. This case also demonstrated the feasibility of PK model-based precision dosing within 48 hours, and documented utility in the setting of changes in renal function. Further PK/PD studies are needed in children with renal dysfunction. DISCLOSURES: All authors: No reported disclosures.