This study is a three-stage cluster randomized historically controlled crossover trial designed to evaluate the feasibility of the implementation of two AS strategies. Four community hospitals in the Duke Infection Control Outreach Network (DICON) will be recruited for this study. Ideally, hospitals will have no teaching affiliation, bed size \<300, and no existing antimicrobial formulary restriction and preauthorization or post-antibiotic prescription review practices in place at study start.

Data will be obtained from the four community hospitals in three stages. In stage 1, historical data from each hospital will be collected for the year prior to study initiation from all participating hospitals. These data are used as a control representing current practice. In stage 2, the four hospitals will be divided into two pairs based upon bed size. One hospital from each pair will be randomly assigned to a six-month period of antimicrobial restriction and preauthorization (Strategy 1; stage 2) followed by a six-month period of post-antibiotic prescription review (Strategy 2; stage 3). The other two hospitals will undergo Strategy 2 in stage 2 followed by Strategy 1 in stage 3 to help alleviate the concern for seasonal/temporal effects when comparing the strategies to each other. A one-month wash out will be performed between each stage. Three antibiotics will be specifically targeted for intervention: anti-pseudomonal carbapenem of choice at the study hospital, vancomycin, and piperacillin-tazobactam. Utilization of alternative antimicrobials, including fluoroquinolones, cephalosporins, and anti-methicillin resistant Staphylococcus aureus (anti MRSA) systemic antimicrobials (e.g., nafcillin, daptomycin, linezolid, ceftaroline, clindamycin, and trimethoprim-sulfamethoxazole (TMP-SMX)) will also be collected. All study hospitals will have electronic systems that track antimicrobial prescriptions through orders, electronic medication administration records (eMAR), bar-coded medication administration (BCMA), or dispensing data.

Hospitals will have dedicated clinical pharmacist time for preauthorization or post-antibiotic review for the three targeted antibiotics in each arm of the study. Pharmacists (PharmDs) at each site will receive standardized training by study personnel in order to address common questions and anticipated arguments, and to establish a robust knowledge base regarding the targeted antimicrobials (anti-pseudomonal carbapenem of choice at the study hospital, vancomycin, and piperacillin-tazobactam). They will also be trained in conflict management.

Study personnel will provide suggested criteria for appropriate use of each targeted drug. Hospital P\&T committees will review, edit (if desired), and approve hospital-specific protocols for appropriate use criteria for each study drug. Pharmacists will be provided with specific clinical pathways for urinary tract infections (UTIs), community-acquired pneumonia (CAP), healthcare-associated pneumonia (HCAP), bacteremia, and "other" uses of targeted antimicrobial. Clinical pathways will be developed jointly by study personnel and based on Centers for Disease Control and Prevention pilot projects. Clinical pharmacists will determine appropriateness of therapy based on study clinical pathways, their baseline knowledge, and acquired knowledge derived by training from study personnel. Time spent performing the two stewardship strategies will be supported by grant funds. The designated pharmacist will be involved in two critical components of the protocol: a) completing the intervention and b) documenting the outcome of the intervention.