For eligible patients, the administration method of beta-lactam antibiotic, either piperacillin-tazobactam or meropenem, will be randomised to either continuous infusion or intermittent infusion over 30 minutes. The choice of beta-lactam antibiotic and the dose and dosing interval (i.e. the dose the patient will receive in 24 hours) will be determined by the treating physician prior to randomisation.