Ceftazidime-avibactam activity against Gram-negative respiratory isolates collected between 2018 and 2019

Abstract

The objective of this study was to assess the in vitro activity of ceftazidime-avibactam (CAZ-AVI) and a panel of comparator agents against isolates of Enterobacter spp., Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa collected in 2018 and 2019 by different centres worldwide from patients with respiratory tract infections. Susceptibility and minimum inhibitory concentration (MIC) of all organisms were determined using broth microdilution methodology for CAZ-AVI, and a panel of comparator antimicrobial agents by a central reference laboratory according to Clinical and Laboratory Standards Institute guidelines and European Committee on Antimicrobial Susceptibility Testing guidelines. CAZ-AVI demonstrated potent antimicrobial activity against isolates of Enterobacter spp. (97.6% susceptibility, MIC90, 1 µg/ml), E. coli (98.5% susceptibility, MIC90, 0.25 µg/ml), K. pneumoniae (94.7% susceptibility, MIC90 2 µg/ml), and P. aeruginosa (91.2% susceptibility, MIC90 8 µg/ml). CAZ-AVI was also active (susceptibility >85%) against MDR isolates for all organisms except P. aeruginosa. Only a small proportion (<10%) of all isolates of Enterobacter spp. and E. coli were identified as XDR compared to isolates of K. pneumoniae and P. aeruginosa isolates (>20%). Susceptibility to CAZ-AVI was high (>70%) among XDR isolates of Enterobacter spp., K. pneumoniae, and E. coli, compared to P. aeruginosa (<70%). Among the comparator agents, only colistin showed consistent activity across all the organisms (>85%). Gram-negative respiratory isolates collected in 2018-2019 showed high susceptibility to CAZ-AVI; CAZ-AVI represents a potential treatment option against infection caused by these organisms.