Trends in Antimicrobial Utilization at a Tertiary Teaching Hospital during a 15-Year Period (1978-1992)

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Abstract
Background: Antimicrobials are a major part of hospital pharmacy budgets and must be considered in resource planning and spending projections. Logically, trends in antimicrobial usage should be linked to trends in resistant pathogens. Objective: To examine long-term trends in antimicrobial use over a 15-year period (1978 to 1992) and contrast them with changes in pathogens causing nosocomial bacteremia. Setting: A 900-bed, tertiary care teaching hospital. Methods: Pharmacy records were reviewed to identify parenteral antimicrobial agents administered to adult inpatients. Results were expressed in average daily adult doses per 1,000 patient days. Results: Chloramphenicol use decreased, while use of penicillin G, antistaphylococcal penicillins, first-generation cephalosporins, and aminoglycosides remained relatively stable. In contrast, there was a sharp increase in the use of second-and third-generation cephalosporins (7-fold and 6.5-fold increase, respectively), vancomycin (161-fold increase), metronidazole (32-fold increase) and amphotericin B (35-fold increase). The proportion of nosocomial bacteremias due to methicillin-resistant gram-positive bacteria rose, but gentamicin resistance in gramnegatives remained at low levels. During the past 14 years, the percentage of patients receiving at least one parenteral antimicrobial rose from 23% to 44%. Among patients receiving antimicrobials, the average number of different agents used per patient increased from 1.8 to 2.1 Conclusions: If newer agents were available, use of older agents usually declined. If newer alternatives were not available, use of older agents rose sharply. The increased use of antimicrobials in adults was related to the expanded proportion of patients receiving these agents.