Antibiotic Selection Logic

An antibiotic order is a working hypothesis: the syndrome suggests a pathogen, and the drug must reach that site at an effective exposure without causing disproportionate harm. For a Canadian NP, selection starts with infection site and severity, then tests the choice against the local antibiogram, prior cultures, recent antibiotic or healthcare exposure, immune status, allergy phenotype, organ function, interactions, and tissue penetration. Obtain appropriate cultures before treatment when collection will not substantially delay therapy. In septic shock or high likelihood of sepsis, give antimicrobials immediately, ideally within one hour of recognition; specimen collection must not delay the first dose. Document the indication, dose, and planned duration. Results and clinical trajectory then determine whether to narrow, change to oral therapy, or stop.