Antibiotic stewardship programs (ASPs) are systematic approaches to optimize antimicrobial use, improving patient outcomes while reducing resistance selection pressure, C. difficile infections, and healthcare costs. Core strategies include: (1) Empiric-to-targeted de-escalation — start broad-spectrum empiric therapy for serious infections, then narrow to the most targeted agent once culture and sensitivity results return. (2) Prospective audit and feedback — ASP pharmacists and infectious disease physicians review antibiotic orders and provide real-time recommendations to prescribers. (3) Formulary restriction and preauthorization — restricting certain broad-spectrum agents (carbapenems, fluoroquinolones) to require ASP approval. (4) Dose optimization — using pharmacokinetic/pharmacodynamic (PK/PD) principles to maximize efficacy while minimizing resistance. Time-dependent antibiotics (beta-lactams): efficacy depends on time above MIC — extended/continuous infusions improve outcomes. Concentration-dependent antibiotics (aminoglycosides, fluoroquinolones): efficacy depends on peak/MIC ratio — high doses with extended intervals optimize killing. (5) Duration optimization — shorter courses are often equivalent (e.g., 5-7 days for uncomplicated pneumonia, 3 days for uncomplicated UTI, procalcitonin-guided discontinuation in sepsis). (6) IV-to-oral switch — transition to oral when patients are clinically improving and can tolerate oral medications (same drug or equivalent bioavailability...