Antibiotic Stewardship

Antimicrobial stewardship is the coordinated use of antibiotics in the right patient, for the right infection, with the narrowest effective agent, dose, route, and duration. Its purpose is better patient outcomes with less resistance, toxicity, disruption of normal flora, and unnecessary cost. It is a patient-safety and quality program—not simply a restriction on prescribing. Antibiotics exert selection pressure. They do not usually create resistance from nothing; susceptible bacteria are suppressed while resistant subpopulations that were already present or acquired resistance determinants survive and multiply. Exposure also selects resistant organisms within the patient's own microbiota, even when the treated pathogen is not resistant. Mobile genetic elements such as plasmids, transposons, and integrons can move resistance determinants between bacterial species. The mechanisms explain why different antibiotic choices fail: - Enzymatic inactivation: beta-lactamases, including extended-spectrum beta-lactamases and carbapenemases, destroy or modify the drug. - Target modification: MRSA produces altered penicillin-binding protein PBP2a through the mecA mechanism; VRE can alter its target through vanA or vanB. - Reduced permeability: porin loss limits entry of some drugs into Gram-negative bacteria. - Active efflux: transport pumps...