Antibiotic misuse in two clinical situations: positive blood culture and administration of aminoglycosides.

Antibiotic use was examined among randomly and prospectively selected cohorts of 79 patients with a positive blood culture and 88 patients given aminoglycosides for a variety of reasons. Appropriateness of antibiotic use was judged daily for each agent according to specific criteria of misuse. For patients with a positive blood culture, 14.3% of antibiotic-days were judged inappropriate in some regard, while for patients given aminoglycosides, 10.2% of antibiotic-days were thought to be inappropriate. The patterns of misuse were similar for the two groups despite disparate selection criteria. The unnecessary use of antibiotics was the single most common type of misuse in both groups, but errors in dosing collectively accounted for nearly one-half of antibiotic misuse. These results suggest that a variety of factors are responsible for misuse of antibiotics. Although the data presented do not allow conclusions about the optimal methods for control of antibiotic misuse, they imply that a multifaceted approach is probably required.