Acute supratherapeutic vancomycin serum concentration in a premature neonate: a case report

Abstract

Vancomycin, a glycopeptide, is a first-line agent in the neonatal population for the treatment of suspected or confirmed Gram-positive infections, including methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative Staphylococci (CoNS).1,2 Vancomycin dosing strategies vary greatly and are generally based on factors such as post-menstrual age (PMA), post-natal age (PNA), and serum creatinine (SCr). Recommended starting doses can range from 10 to 15 mg/kg/dose every 6 to 48 hours, depending upon infection site, suspected organism, desired serum vancomycin trough concentration/area under the curve (AUC), and/or minimal inhibitory concentration (MIC) to vancomycin. Nephrotoxicity in patients receiving vancomycin has been systematically documented in adults and less often in neonates, with a reported occurrence of 1-9% when receiving recommended dosing.1 Risk of toxicity can be minimized through dosage modifications and close monitoring of SCr and urine output at baseline and throughout therapy.2 This case report describes the use of vancomycin, dosed at 10 mg/kg, in a premature infant born at 26 weeks and 4 days gestation for CoNS pneumonia. The infant showed signs of renal dysfunction, prompting a pre-steady state vancomycin serum concentration lab draw, resulting in a concentration of 102.2 µg/mL. Serial repeat vancomycin serum concentrations showed a linear excretion pattern and an ARCHITECT iVancomycin assay completed by medical laboratory scientists confirmed the concentration of the vancomycin aliquot prepared by the inpatient pharmacy department. Renal ultrasound established return to normal renal function; however, the infant failed routine newborn hearing screening upon NICU (neonatal intensive care unit) discharge due to suspected vancomycin-induced ototoxicity.