To describe the real-world clinical use of ceftolozane/tazobactam (C/T) and associated outcomes in France.

Multicenter, prospective cohort study conducted in 22 hospitals. All adult patients who received at least one dose of C/T were asked to participate (2018-2019). Patients were treated according to standard hospital practice and followed up until C/T stop.

At the time of the analysis, 84 patients were evaluated. The median age was 64.8 years, and 67.9% (57/84) of patients were males. Fifty-seven patients (57/82, 69.5%) had one or more risk factors for multidrug-resistant (MDR) infections (missing MDR risk factor data for two patients). Most patients were critically ill and had several comorbidities. A majority (59/84, 70.2%) of patients had nosocomial infections. Half of all patients (n=42) had a diagnosis of pneumonia, of which 69% (29/42) were hospital acquired. Overall, 90.5% (76/84) of patients had MDR bacteria. Pseudomonas aeruginosa was the most frequently isolated bacterium (71/80, 88.8%), including 93% (80/86) of C/T-susceptible strains. C/T was prescribed as the first-line treatment to 29.8% (25/84) of patients. A concomitant antibiotic treatment was prescribed to 48.8% (41/84) of patients, of whom 65.9% (27/41) were prescribed concomitant antibiotics at the same time as C/T initiation. Empirical C/T prescription was microbiologically appropriate in 11/16 patients after susceptibility testing. Most patients (44/72, 61.1%) were cured and four (4/72, 5.6%) deaths were reported.

The results showed that C/T was most frequently prescribed for documented cases of P. aeruginosa infections. Most outcomes were positive, including among pneumonia patients.