Activity of aztreonam in combination with ceftazidime-avibactam against serine- and metallo-β-lactamase-producing Pseudomonas aeruginosa

Existing data support the combination of aztreonam and ceftazidime-avibactam against serine-beta-lactamase (SBL)- and metallo-beta-lactamase (MBL)-producing Enterobacterales, although there is a paucity of data against SBLand MBL-producing Pseudomonas aeruginosa. In this study, 5 SBLand MBL-producing P. aeruginosa (1 IMP, 4 VIM) were evaluated against aztreonam and ceftazidime-avibactam alone and in combination via broth microdilution and time-kill analyses. All 5 isolates were nonsusceptible to aztreonam, aztreonam-avibactam, and ceftazidime-avibactam. Combining aztreonam with ceftazidime-avibactam at subinhibitory concentrations produced synergy and restored bactericidal activity in 4/5 (80%) isolates tested. These results suggest that the combination of aztreonam and ceftazidime-avibactam may be a viable treatment option against SBLand MBL-producing P. aeruginosa. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

The combination of aztreonam and ceftazidime-avibactam shows promising results against SBL and MBL-producing Enterobacterales, although data on Pseudomonas aeruginosa are lacking. Subinhibitory concentrations of the two drugs produced synergy and restored bactericidal activity in most isolates tested, suggesting it may be a viable treatment option.