Evaluation of a Formulary Change on Outcome of Infection and Antimicrobial Resistance in a Medical Intensive Care Unit

Abstract

All patients in a 20-bed medical intensive care unit (ICU) were prospectively followed for a 4-month period (phase I: 390 patients/2379 patient days) to collect baseline information, and were then followed for an additional 4 months (phase II: 383 patients/2260 patient days) after a decrease in use of piperacillin-tazobactam substituted with cefepime. Total infections in phase I versus phase II were lower respiratory tract infection (LRTI), 214 patients (55%) versus 203 patients (53%); urinary tract infection (UTI), 94 patients (24%) versus 96 patients (25%); and sepsis of undetermined etiology, 70 patients (18%) versus 65 patients (17%). There were no significant differences in death (22 % vs. 19%), cure or improvement of infection (53% vs. 56%), readmission to the unit (3.5% vs. 3.2%), hospital risk of death (29.8 vs. 30.2), mean length of ICU stay (6.1 days vs. 5.9 days), or rates of nosocomial infection (6.3 vs. 5.1 for LRTI, 4.0 vs. 4.2 for UTI, soft tissue infection [STI] 0.8 vs. 0.0, bacteremia 0.8 vs. 1.0, and intravenous catheter infection 2.1 vs. 1.0 per 1000 patient days), in phase I and phase II, respectively. Costs of antimicrobial acquisition were $548 versus $433 per patient in phase I and phase II (P < 0.001). Mean per patient antimicrobial treatment costs of piperacillin-tazobactam were $145 versus $100 and cefepime were $80 versus $105 in phases I and II, respectively (P < 0.01). The rates of infection and colonization with Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli were unchanged in both study periods. There were 68 versus 39 Staphylococcus aureus (P < 0.001), of these 84% versus 87% methicillin-resistant S. aureus and 11 versus 9 E. faecium (82% vs. 78% VREF) in phases I and II, respectively. When piperacillin-tazobactam substituted for cefepime in addition to utilization of practice guidelines in medical ICU, there was a decrease in piperacillin-tazobactam use, costs, and medical ICU acquired S. aureus infections without adversely affecting outcome of infection or antimicrobial resistance.