A multicenter study on optimizing piperacillin-tazobactam use: lessons on why interventions fail.

We examined interventions to optimize piperacillin-tazobactam use at 4 hospitals. Interventions for rotating house staff did not affect use. We could target empiric therapy in only 35% of cases. Because prescribing practices seemed to be institution specific, interventions should address attitudes of local prescribers. Interventions should target empiric therapy and ordering of appropriate cultures.