The effect of limiting antimicrobial therapy duration on antimicrobial resistance in the critical care setting.

Background: Using antimicrobial agents for prolonged periods of time and/or in heavy densities is known to contribute to antimicrobial resistance.

Methods: A quasiexperimental, before and after study to limit the duration of antimicrobial therapy to 14 days was conducted in a medical-surgical intensive care unit (ICU). An intervention to optimize antimicrobial therapy was performed when antimicrobial agents had been prescribed for more than 14 days. We then compared antimicrobial utilization using the defined daily dose (DDD) per 1000 patient-days, as well as resistance rates in selected organisms in the intervention phase to the previous 10-month period.

Results: In the intervention phase, doctors approved to discontinue the antimicrobial therapy before 14 days in 89.8% (415/462) of the prescribed antibiotics in the ICU. Comparing the 2 time periods, we found a reduction in carbapenems (24.5% decrease), vancomycin (14.3% decrease), and cephalosporins (12.2% decrease) in the intervention phase. Imipenem resistance decreased in Acinetobacter baumannii from 88.5% to 20.0% (P
Conclusion: These results suggest that an intervention to reduce the duration of antimicrobial therapy contributed to more rational use of antimicrobial agents and to the reduction of bacterial resistance in the critical care setting.