Piperacillin/Tazobactam Use in Extended-Spectrum Beta-Lactamase Infections

The primary outcome of the study, which seeks to fully assess infection-related clinical outcomes and microbiological cure rates of PZT for ESBL infections, was clearance of the causative organism from index infection site on first follow-up culture.

When compared head-to-head with carbapenems such as meropenem (MERO), studies have shown that there is no significant difference in mortality in patients whose extended-spectrum beta-lactamase (ESBL) infections are treated with piperacillin-tazobactam (PZT), though the literature to date has been limited primarily to monomicrobial urinary infections with Escherichia coli.

Now, investigators with Larkin University College of Pharmacy and Larkin Community Hospital’s Palm Springs Campus are presenting initial findings of a research-in-progress retrospective cohort study at the 22nd annual Making a Difference in Infectious Diseases (MAD-ID 2019) meeting. ​Melissa Santibañez, PharmD, assistant professor of clinical care at Larkin University College of Pharmacy and an investigator on the study, shared updates with Contagion® (see video).

Patients admitted to Larkin Community Hospital Palm Springs Campus between April 2018 and December 2018 with any confirmed ESBL-positive culture sensitive to both PZT and MERO were eligible for inclusion in the study. The research team used only the first ESBL-positive culture per admission, and included patients were those admitted from >48 hours from index culture collection and who received definitive treatment with PZT or MERO for >48 hours after culture result.

The primary outcome of the study, which seeks to fully assess infection-related clinical outcomes and microbiological cure rates of PZT for ESBL infections, was clearance of the causative organism from index infection site on first follow-up culture.

A total of 16 patients had ESBL-positive index cultures between April 2018 and June 2018. The average patient age was 82.0 + 11.2 years, 5 patients were male, 9 were admitted from home, and 7 patients were admitted from outside facilities.

Data continue to be collected through December 2018, but preliminary analysis indicates that index cultures were obtained from urine in 14 patients and from blood in 2 patients. E coli was the causative organism in 14 patients, while 2 patients had cultures positive for Klebsiella pneumoniae. Four patients received PZT as definitive therapy, while 12 received MERO.

“Four patients with ESBL E coli had repeat cultures, and 100% achieved microbiological cure. None of the 4 patients whose definitive therapy escalated from PZT to MERO achieved microbiological cure,” investigators reported. “The mortality rate was 12.5% (2 patients).”

In conclusion, investigators found that, among evaluable patients, microbiological cure rate was 100%, limited to predominantly E coli urinary infections.

The study, “Clinical Outcomes Associated with Piperacillin/Tazobactam Use in Extended-spectrum Beta-lactamase Infections,” was presented at MAD-ID 2019, held May 8-11, 2019, in Orlando, Florida.