Rational use of antibiotics in the intensive care unit: impact on microbial resistance and costs

Objective: To evaluate the impact of an intensive care unit (ICU) antibiotic-use policy on the microbial resistance in nosocomial infections and costs. Design: Comparative study before and after policy implementation. Settings: An eleven-bed ICU in a general hospital. Patients: All patients admitted for at least 48 h during a 5 year period (1994-1998). Interventions: In 1995, implementation of an antibiotic-use policy. Measurements and main results Patients' general characteristics, incidence of nosocomial infections, antibiotic-selective pressure (the number of days of antibiotic treatment for 1,000 days of presence in the ICU), presence and types of multi-resistant micro-organisms and costs linked to antibiotic use were recorded before (1994) and after implementation of the policy (1995-1998). For each year, patients' general characteristics and the incidence of nosocomial infections were the same. Costs linked to antibiotics use showed a progressive reduction (100% for 1994, 81% for 1995, 65% for 1998). Antibiotic-selective pressure diminished (from 940 days of antibiotic use per 1,000 days ( 1994) to 610 (1998), p < 10(-5)). A statistically significant reduction in nosocomial infections due to antimicrobial resistant micro-organisms was observed (from 37% (1994) to 15% (1998) of nosocomial infections, p < 10(-5)) after 3 years of implementation of the policy, essentially due to a reduction in methicillin-resistant Staphylococcus aureus and ceftriaxone-resistant Enterobacteriaceae. Nosocomial infections due to ceftazidime-resistant Pseudomonas species or extended-spectrum beta-lactamase Enterobacteriaceae showed no reduction. Conclusions: Antibiotic-use policy allowed a reduction in antibiotic-selective pressure, costs linked to antibiotics and selective reduction of nosocomial infections due to antimicrobial resistant micro-organisms.