Randomized, multicenter, double-blind study of efficacy, safety, and tolerability of intravenous ertapenem versus piperacillin/tazobactam in treatment of complicated intra-abdominal infections in hospitalized adults.

Background: Complicated intra-abdominal infections are a common problem in surgical practice. This study compared the effectiveness of ertapenem (1 g qd) and piperacillin/tazobactam (3.375 g q6h) in the treatment of these infections.

Methods: This was a multicenter, double-blinded, randomized study conducted in patients with complicated intra-abdominal infections. Of the 535 patients screened, 500 were stratified on the basis of disease severity (Acute Physiology and Chronic Health Evaluation [APACHE] II score < or =10 or >10), then randomized (1:1) to 4-14 days of treatment with one of the regimens and six weeks of followup. Nearly all patients (N = 494) were treated. The primary endpoint was the proportion of microbiologically evaluable patients with a favorable clinical response (cure) at two weeks. Non-inferiority of ertapenem was based on a difference in response rate of <15 percentage points compared with piperacillin/tazobactam (lower bound of the 95% CI > -15).

Results: Of the 494 treated patients, 231 were microbiologically evaluable, with 123 and 108 patients in the ertapenem and piperacillin/tazobactam groups, respectively. Statistically similar cure rates were observed in the ertapenem (82.1%) and piperacillin/tazobactam (81.7%) groups (difference 0.3 [95% CI: -9.6, 10.5]). The pathogens isolated most frequently were Escherichia coli, Bacteroides fragilis, and Bacteroides thetaiotamicron, typical isolates associated with intra-abdominal infections. There were no statistical differences between the groups in serious drug-related clinical adverse events, drug-related clinical adverse experiences leading to study discontinuation, or mortality.

Conclusions: Ertapenem was non-inferior to piperacillin/tazobactam in the cure of intra-abdominal infections caused by susceptible pathogens. Both study drugs generally were well tolerated.