Antimicrobial pharmacology requires the NP to integrate understanding of pathogen biology, drug mechanisms, pharmacokinetic/pharmacodynamic (PK/PD) principles, and stewardship concepts to optimize treatment outcomes while minimizing resistance development. Antimicrobial mechanisms are classified by their molecular targets. Beta-lactams (penicillins, cephalosporins, carbapenems, monobactams) inhibit bacterial cell wall synthesis by binding penicillin-binding proteins (PBPs) and preventing transpeptidation of peptidoglycan cross-links, leading to osmotic lysis. They exhibit time-dependent killing, meaning efficacy correlates with the duration that free drug concentration exceeds the MIC (fT>MIC). Aminoglycosides (gentamicin, tobramycin, amikacin) bind the 30S ribosomal subunit, causing misreading of mRNA and production of nonfunctional proteins; they exhibit concentration-dependent killing with a post-antibiotic effect, making once-daily extended-interval dosing effective. Fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin) inhibit DNA gyrase and topoisomerase IV, preventing DNA supercoiling and replication; they also demonstrate concentration-dependent killing. Macrolides (azithromycin, erythromycin, clarithromycin) bind the 50S ribosomal subunit blocking peptide translocation; primarily bacteriostatic. Vancomycin binds D-Ala-D-Ala terminal of peptidoglycan precursors, preventing cell wall cross-linking; effective against gram-positive organisms only because the large molecule cannot penetrate gram-negative outer membranes. PK/PD optimization is essential for treatment success. Time-dependent antibiotics (beta-lactams, carbapenems) are...