Rates of Resistance to Ceftazidime-Avibactam and Ceftolozane-Tazobactam Among Patients Treated for Multidrug-Resistant Pseudomonas aeruginosa Bacteremia or Pneumonia.

Shah, Sunish; Kline, Ellen G; Haidar, Ghady; Squires, Kevin M; Pogue, Jason M; McCreary, Erin K; Ludwig, Justin; Clarke, Lloyd G et al. · Clin Infect Dis · 2025

retrospective_cohort · Level III

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Abstract

Among consecutive patients with multidrug-resistant Pseudomonas aeruginosa bacteremia or pneumonia we found those treated with ceftazidime-avibactam were more likely to develop resistance (defined as ≥4-fold increased MIC) than those treated with ceftolozane-tazobactam (40% vs 10%; P = .002). Ceftazidime-avibactam resistance was associated with new mutations in ampC and efflux regulatory pathways.

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