Background:Increasing concern about inappropriate antibiotic use prompted us to examine whether our patients were receiving frequent and perhaps unwarranted changes of antibiotic therapy.Methods:We evaluated antibiotic prescribing by the physicians in the Emergency Department and by those on the inpatient medical service during the first 72 hours of hospitalization in 119 patients admitted with suspected serious infections to an acute care, university-affiliated, municipal teaching hospital. The appropriateness of antibiotic prescriptions was assessed independently and retrospectively by 2 infectious disease specialists (each based at a different hospital) using a 4-grade scale (from 1 = wrong choice to 4 = appropriate). Of their evaluations of the 427 antibiotic regimens given to the 119 patients during 4 defined intervals during their first 72 hours of hospitalization, 90% agreed with each other within 1 grade. Their evaluations were then compared with the selections that had been made at each interval by the prescribing physicians.Results:Successive prescribing physicians changed the antibiotic regimens in 77% of cases during the first 24 hours and in 56% during the next 48, often without apparent clinical or microbiologic indications. By 72 hours, the 119 patients had received a mean of 3.1 ± 1.3 (±SD) different antibiotics, and 40 received between 4 and 7. Only 7% of the patients had no change in the regimen prescribed originally.Conclusions:Many patients had multiple changes of antibiotics, often unnecessarily, resulting in exposure to too many agents.