Background: The prevalence of vancomycin-resistant enterococci (VRE) is increasing, despite infection control measures. Limited data link ticarcillin-clavulanate to higher VRE prevalence.
Methods: Active surveillance for VRE was conducted before and after a formulary switch from ticarcillin-clavulanate to piperacillin-tazobactam. Rectal swabs were obtained serially in 863 adult patients admitted to intensive care units (ICUs) between November 1, 2000 and September 30, 2004.
Results: In the postswitch period, 38 of 497 (7.6%) patients acquired VRE versus 42 of 366 (11.5%) patients in the preswitch period. Survival analysis showed an overall hazard ratio (HR) of .68 postswitch versus preswitch ( P = .07), with the greatest change in the surgical ICU (HR = .17, P = .006). Multivariate analysis showed an overall HR = .51 ( P = .004). Hospital-wide, nonstool VRE clinical cultures fell from 39 (.58/1000 patient days) in the 10-month preswitch period to 27 (.33/1000 patient days) in the 12-month postswitch period. Infection control practices and use of other antibiotics remained stable.
Conclusions: VRE acquisition appeared to decrease in association with a formulary change from ticarcillin-clavulanate to piperacillin-tazobactam.