Searching for the Optimal #Treatment for Metallo- and Serine-β-Lactamase Producing #Enterobacteriaceae: #Aztreonam in Combination with #Ceftazidime-avibactam or #Meropenem-vaborbactam (AAC, abstract)

[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]

Searching for the Optimal Treatment for Metallo- and Serine-β-Lactamase Producing Enterobacteriaceae: Aztreonam in Combination with Ceftazidime-avibactam or Meropenem-vaborbactam

M Biagi, T Wu, M Lee, S Patel, D Butler, E Wenzler

DOI: 10.1128/AAC.01426-19




Metallo-β-lactamase (MBL)-producing Enterobacteriaceae, particularly those that co-harbor serine β-lactamases, are a serious emerging public health threat given their rapid dissemination and the limited number of treatment options. Pre-clinical and anecdotal clinical data support the use of aztreonam in combination with ceftazidime-avibactam against these pathogens, but other aztreonam-based combinations have not been explored. The objective of this study was to evaluate the in vitro activity and compare synergy between aztreonam in combination with ceftazidime-avibactam and meropenem-vaborbactam against serine and MBL-producing Enterobacteriaceae via time-kill analyses.


8 clinical Enterobacteriaceae strains (4 Escherichia coli and 4 Klebsiella pneumoniae) co-producing NDM and at least one serine β-lactamase were used for all experiments. Drugs were tested alone, in dual β-lactam combinations, and in triple drug combinations against all strains.


All strains were resistant to ceftazidime-avibactam and meropenem-vaborbactam and 7/8 (87.5%) strains were resistant to aztreonam. Aztreonam combined with ceftazidime-avibactam was synergistic against all 7 aztreonam-resistant strains. Aztreonam combined with meropenem-vaborbactam was synergistic against all aztreonam-resistant strains with the exception of an OXA-232-producing K. pneumoniae strain. Neither triple combination was synergistic against the aztreonam-susceptible strain. Likewise, neither dual β-lactam combination was synergistic against any strain.


These data suggest that aztreonam plus meropenem-vaborbactam has similar activity to aztreonam plus ceftazidime-avibactam against Enterobacteriaceae producing NDM and other non-OXA-48-like serine β-lactamases. Confirmation of these findings in future in vitro and in vivo models is warranted.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Antibiotics; Drugs Resistance; Beta-lactams; NDM; Aztreonam; Meropenem; Vaborbactam; Ceftazidime; Avibactam; Enterobacteriaceae.


Averting the #postantibiotic era: successful use of #meropenem/vaborbactam for #carbapenem-resistant #Serratia marcescens and #Enterobacter aerogenes bacteraemia in a haemodialysis patient (J Antimicrob Chemother., abstract)

[Source: Journal of Antimicrobial Chemotherapy, full page: (LINK). Abstract, edited.]

Averting the post-antibiotic era: successful use of meropenem/vaborbactam for carbapenem-resistant Serratia marcescens and Enterobacter aerogenes bacteraemia in a haemodialysis patient

Sarah C J Jorgensen, Philip McDonald, Ryan P Mynatt, Jason M Pogue, Stephen A Lerner, Sorabh Dhar, Hossein Salimnia, Michael J Rybak

Journal of Antimicrobial Chemotherapy, dky346,

Published: 04 September 2018


The prevalence of carbapenem-resistant Enterobacteriaceae (CRE) has increased dramatically over the past two decades, fuelling speculation that we are nearing the ‘post-antibiotic era’ and attesting to the critical need for novel antibiotics with activity against MDR pathogens.1 In 2015 the US FDA approved ceftazidime/avibactam for the treatment of complicated urinary tract infections (cUTIs) and complicated intra-abdominal infections caused by MDR Gram-negative bacteria.2 The introduction of ceftazidime/avibactam represented significant progress in the treatment of CRE, with accumulating real‐world data demonstrating improved efficacy and safety compared with older, more toxic antibiotics.3–5However, treatment failure rates as high as 30%–50% have been…



Issue Section: Research letter

© The Author(s) 2018. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email:

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Keywords: Antibiotics; Drugs Resistance; Carbapenem; Serratia marcescens; Enterobacter aerogenes; Bacteremia; Meropenem; Vaborbactam.