Comparison of the In Vitro Activities of Ceftazidime-avibactam and Ceftolozane-tazobactam against Clinical Isolates of Pseudomonas aeruginosa: ATLAS Global Surveillance Program 2020-2024.

OBJECTIVES

To provide a descriptive analysis of the in vitro antimicrobial susceptibility testing results for all 39,661 Pseudomonas aeruginosa isolates collected by the ATLAS global surveillance program data from 2020 to 2024 with a focus on ceftazidime-avibactam and ceftolozane-tazobactam activities against carbapenem-resistant and DTR (difficult-to-treat resistance) phenotypes.

METHODS

MICs were determined using reference CLSI broth microdilution testing and interpreted by 2026 CLSI and EUCAST breakpoints.

RESULTS

Ceftazidime-avibactam (90.6% susceptible; MIC90, 8 µg/mL) and ceftolozane-tazobactam (89.8% susceptible; MIC90, 8 µg/mL) demonstrated similar in vitro activities against all P. aeruginosa isolates. Percent susceptible values for ceftazidime-avibactam, ceftolozane-tazobactam, and meropenem were lowest in Africa (ceftazidime-avibactam, 84.6%; ceftolozane-tazobactam, 82.1%; meropenem, 74.0%) and Latin America (86.5%; 84.7%; 69.8%), and highest in North America (94.8%; 95.1%; 81.6%) and the South Pacific (96.2%; 96.3%; 88.9%). Annual percent susceptible values for ceftazidime-avibactam (range, 90.2% in 2023 to 91.6% in 2022) and ceftolozane-tazobactam (range, 89.6% in 2023 to 90.8% in 2022) did not change over the five years studied. Overall, 26.1% of isolates were carbapenem-resistant; 68.0% and 65.6% of carbapenem-resistant isolates were ceftazidime-avibactam-susceptible and ceftolozane-tazobactam-susceptible, respectively. A DTR phenotype was present for 8.0% of isolates; 30.4% and 28.5% of DTR isolates were ceftazidime-avibactam-susceptible and ceftolozane-tazobactam-susceptible, respectively. In total, 4,641 of all 39,661 isolates (11.7%) were ceftazidime-avibactam-resistant and/or ceftolozane-tazobactam-nonsusceptible; 67.5% of these isolates were both ceftazidime-avibactam-resistant and ceftolozane-tazobactam-nonsusceptible, 19.6% were ceftolozane-tazobactam-nonsusceptible and ceftazidime-avibactam-susceptible, and 12.9% were ceftazidime-avibactam-resistant and ceftolozane-tazobactam-susceptible.

CONCLUSION

Approximately 90% of global clinical isolates of P. aeruginosa from 2020 to 2024 remained susceptible to ceftazidime-avibactam and ceftolozane-tazobactam.