Piperacillin, Tazobactam Drug Combination

The goal of this clinical trial is to learn whether subcutaneous piperacillin/tazobactam can provide drug exposure similar to standard intravenous piperacillin/tazobactam in adults who need treatment for an infection. It will also assess safety and clinical outcomes. The main questions it aims to answer are: * Does subcutaneous piperacillin/tazobactam achieve pharmacokinetic exposure comparable to intravenous treatment? * Is subcutaneous piperacillin/tazobactam safe and feasible in this population? Researchers will compare subcutaneous continuous infusion with intravenous continuous infusion to see whether the subcutaneous route is not clinically worse than the standard intravenous route. Participants will: * Receive piperacillin/tazobactam by subcutaneous or intravenous continuous infusion after randomization * Have blood samples collected for pharmacokinetic assessments * Undergo safety, clinical, and end-of-treatment assessments during the study period