The treatment of serious bacterial infections is complicated by the fact that time to initiation of effective antimicrobial therapy is a strong predictor of mortality. Therefore, therapy must be initiated before the causative pathogen is identified. However, inappropriate or inadequate initial empirical therapy is associated with increased mortality, morbidity, and length of hospital stay. Initial empirical therapy with broad-spectrum antimicrobials attempts to address this dilemma by "getting it right up front." The goal is to provide treatment active against the most likely pathogens until culture/susceptibility test results are obtained. After the causative pathogen is identified, streamlining to more-precise therapy of the shortest acceptable duration is implemented. In this way, the risks of death, morbid complications, increased duration of hospital stay (as a result of ineffective initial treatment), and emergence of resistance (due to extended treatment with broad-spectrum agents) are lowered. Improved clinical and economic outcomes after such an approach have been demonstrated.