Impact of a hospital-wide antimicrobial formulary intervention on the incidence of multidrug-resistant gram-negative bacteria.

We examined the impact of an antimicrobial formulary change, based on reduction in third-generation cephalosporin use, on resistant gram-negative pathogens in a tertiary hospital. No significant changes were demonstrated in their incidence per 1000 patient-days. Otherwise, there was a significant decrease in rate of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae (63.1% to 52.5%, P = .04) and third-generation cephalosporin-resistant Enterobacter species (31.4% to 25%, P = .04) between the 2 study periods. On the other hand, there was also a significant increase in rate of ampicillin-sulbactam-resistant Acinetobacter baumannii (8% to 47%, P = .01) after the implementation of the formulary intervention.