Comparison of ceftolozane/tazobactam and meropenem in treating bloodstream infections caused by extended-spectrum β-lactamase-producing Enterobacterales: a single-centre, retrospective, real-world study

OBJECTIVES: Ceftolozane/tazobactam has been developed as a novel carbapenem-sparing agent. Our study aimed at comparing the effectiveness of ceftolozane/tazobactam versus meropenem for the treatment of bloodstream infections (BSIs) due to ESBL producers. METHODS: This retrospective study was conducted at the Laiko General Hospital of Athens from 1 January 2022 to 28 February 2024. Patients with BSIs due to ESBL-producing Enterobacterales were identified using electronic health records. Inverse probability of treatment weighting (IPTW) was used to compare the two treatment modalities. The primary endpoint was 30 day all-cause mortality; secondary endpoints included clinical cure, in-hospital mortality and antibiotic consumption. RESULTS: We identified 144 patients with ESBL BSIs, of whom 115 were included in our analysis (ceftolozane/tazobactam, n = 41 versus meropenem, n = 74). The mean age was 73.6 ± 14.1 years and 55.7% (64/115) were male. Persons treated with ceftolozane/tazobactam were older (78.2 ± 13.3 versus 70.9 ± 14 years, P = 0.008) and their isolates were more likely to be susceptible to cefoxitin (2.4% versus 21.6%, P = 0.005). There were no significant differences between the two groups in clinical cure rates (68.3% versus 75.7%, P = 0.511), in-hospital mortality (34.1% versus 29.7%, P = 0.677) or 30 day mortality (34.1% versus 29.7%, P = 0.677). These findings were confirmed by IPTW analysis, which showed no difference between ceftolozane/tazobactam and the carbapenem for clinical cure (OR 0.43, 95% CI 0.12-1.53, P = 0.193), hospital mortality (OR 1.72, 95% CI 0.54-5.51, P = 0.360) and 30 day mortality (OR 1.72, 95% CI 0.54-5.48, P = 0.357). CONCLUSIONS: Ceftolozane/tazobactam is a viable alternative to meropenem for the treatment of ESBL BSIs. Prospective studies are needed to confirm these findings.