A challenge to intermittent vancomycin dosing in young infants is the avoidable delay caused by the need to wait until steady state (i.e. when the drug concentrations are in equilibrium) to measure a vancomycin concentration, as this generally occurs 24 to 48 hours after starting treatment. If the target concentration is not achieved, the dose needs to be adjusted, resulting in further delays in an infant achieving the concentration required to treat their infection. The purpose of this study is to assess the use of early therapeutic drug monitoring (first-dose trough) and, if needed, early dose adjustment, in achieving target vancomycin concentrations at steady state. A dose adjustment calculator (available through a web application) will be used to determine the need for dose adjustment (based on predicted steady state concentration) and recommend an adjusted dose if required.