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A systematic review and individual bacterial species level meta-analysis of in vitro studies on the efficacy of ceftazidime/avibactam combined with other antimicrobials against carbapenem-resistant Gram-negative bacteria

Assefa GM, Roberts JA, Aslan AT, Mohammed SA, Sime FB

The Journal of antimicrobial chemotherapy, 2025

9 citations

Abstract

Background: Carbapenem-resistant Gram-negative bacteria (CR-GNB) develop resistance to many antimicrobials. To effectively manage infections caused by these organisms, novel agents and/or combinations of antimicrobials are required.

Objectives: Evaluated the in vitro efficacy of ceftazidime/avibactam in combination with other antimicrobials against CR-GNB.

Methods: PubMed, Web of Science, Embase and Scopus were searched. Study outcomes were quantified by counting the number of isolates exhibiting synergy, defined as a fractional inhibitory concentration index ≤ 0.5 for checkerboard and Etest, and a >2 log cfu/mL reduction for time-kill studies. The proportion of synergy was calculated as the ratio of isolates exhibiting synergy to the total number of isolates tested. These proportions were analysed using a random-effects model, following the Freeman-Tukey double-arcsine transformation.

Results: Forty-five in vitro studies were included. A total of 734 isolates were tested, and 69.3% of them were resistant to ceftazidime/avibactam. The combination of ceftazidime/avibactam with aztreonam showed a high synergy rate against carbapenem-resistant Klebsiella pneumoniae (effect size, ES = 0.91-0.98) and Escherichia coli (ES = 0.75-1.00). Ceftazidime/avibactam also demonstrated a high synergy rate (ES = 1) in time-kill studies when combined with azithromycin, fosfomycin and gentamicin against K. pneumoniae. Compared to ceftazidime/avibactam alone, a higher bactericidal rate was…

How strong is the evidence?

Evidence Hub reads this as a meta-analysis, done in cell cultures (in vitro), not in people. Its evidence level is 5 of 5 (Very low · case / narrative / animal / in vitro / in silico). Case reports, narrative reviews, and animal, cell or computer-model studies give the weakest evidence for human health.

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