In contrast to expanded-spectrum
cephalosporins,
beta-lactam-
beta-lactamase inhibitor combinations such as
piperacillin-tazobactam have rarely been associated with
vancomycin-resistant Enterococcus (VRE) colonization and
infection. In mice,
piperacillin-tazobactam has sufficient antienterococcal activity to inhibit the establishment of colonization during treatment, but this effect has not been confirmed in human patients. We prospectively evaluated the acquisition of rectal colonization by VRE among intensive care unit patients receiving
antibiotic regimens containing
piperacillin-tazobactam versus those receiving
cefepime, an expanded-spectrum
cephalosporin with minimal antienterococcal activity. Rectal swabs were obtained weekly and were cultured for VRE. For 146 patients with a negative rectal swab for VRE prior to
therapy, there was no significant difference in the frequency of VRE acquisition between patients receiving
piperacillin-tazobactam- and
cefepime-containing regimens (19/72 [26.4%] and 23/74 [31.1%], respectively; P = 0.28). Of the 19 patients who acquired VRE in association with
piperacillin-tazobactam, 10 (53%) developed the new detection of VRE during
therapy. Patients initiated on treatment with
cefepime-containing regimens were significantly more likely than those initiated on treatment with
piperacillin-tazobactam-containing regimens to have received
antibiotic therapy in the prior 30 days (55/74 [74.3%] and 22/72 [30.6%], respectively; P < 0.001). These findings suggest that
piperacillin-tazobactam- and
cefepime-containing
antibiotic regimens may be associated with the frequent acquisition of VRE in real-world intensive care unit settings. Although
piperacillin-tazobactam inhibits the establishment of VRE colonization in mice when exposure occurs during treatment, our data suggest that this agent may not prevent the acquisition of VRE in patients.