Antimicrobial Monotherapy versus Combination Therapy for the Treatment of Complicated Intra-Abdominal Infections

It is unknown if β-lactam monotherapy is sufficient for complicated intra-abdominal infections or if broader coverage is required, such as with vancomycin. This study sought to determine the clinical outcomes of piperacillin/tazobactam (PIP/TAZ) monotherapy compared to combination therapy with vancomycin and PIP/TAZ for complicated intra-abdominal infections among patients within a surgical intensive care unit (ICU).

Retrospective cohort study.

Three surgical ICUs at a tertiary academic medical center.

Four hundred seventeen patients with a secondary peritonitis identified by International Classification of Diseases, Ninth Revision codes who received either PIP/TAZ monotherapy (228 patients) or PIP/TAZ and vancomycin combination therapy (189 patients).

The primary outcome was day 28 clinical cure; secondary outcomes included day 7 clinical cure, length of stay (LOS), and mortality. There were no statistically significant differences between the monotherapy and combination therapy groups with respect to day 28 clinical cure (33.9% vs 25.5%, p=0.064), day 7 clinical cure (23.6% vs 17.6%, p=0.14), or 28-day mortality (7% vs 7.9%, p=0.72). LOS in the ICU was significantly shorter in the monotherapy group (6 days) compared with the combination therapy group (7 days; p=0.04); however, hospital LOS was not significantly different.

No difference was observed in clinical cure rates at day 28 or day 7 between those who received PIP/TAZ monotherapy compared to PIP/TAZ and vancomycin combination therapy.