Prescribing Patterns and Clinical Effectiveness of Ceftolozane/Tazobactam for ESBL-Producing Enterobacterales: A SPECTRA Real‑World Multi‑Country Analysis

Background: Ceftolozane/tazobactam (C/T) has demonstrated activity against ESBL-producing Enterobacterales (ESBL-E) and provides a carbapenem-sparing option. Broader use of C/T alongside other carbapenem/inhibitor combinations may expand therapeutic choices and reduce selection pressure for carbapenem resistance, supporting antimicrobial stewardship and limiting the spread of carbapenem-resistant Enterobacterales. Methods: SPECTRA was a multicentre, retrospective real-world study of hospitalized adults (≥18 years) who received ≥48 hours of C/T across seven countries (Australia, Austria, Germany, Italy, Mexico, Spain, UK) from January 2016 to November 2020. Medical-record data were collected for up to 6 months before treatment and 30 days after the final C/T dose (or until death). This sub-analysis describes clinical outcomes and healthcare utilization in patients with laboratory-confirmed ESBL-E (n=39). Results: Thirty-nine ESBL-E patients were included (mean age 59.3 years; 56.4% male); 79.5% had ≥1 comorbidity (mean 2.2 per patient). Common pathogens were Escherichia coli (n=23) and Klebsiella spp (n=12). Investigator-assessed clinical success was 64.9%, microbial eradication was 27.0%, in-hospital mortality was 20.5%, and 30-day readmission was 5.1%. ICU admission during the index hospitalisation occurred in for 38.5% of patients (mean ICU stay 16.0 days). Median treatment duration was 11 days while mean hospital stay after C/T initiation was 13.5 days. Conclusions: In this real-world multi-country cohort, C/T showed clinical effectiveness in ESBL-E infections, with outcomes consistent with the overall SPECTRA population. C/T offers a carbapenem-sparing strategy that broadens treatment options and may help reduce reliance on carbapenems, supporting efforts to limit carbapenem-resistant Enterobacterales. Findings warrant evaluation in larger and comparative studies.