Abstract | Objectives: Diazabicyclooctanes (DBOs) inhibit class A, class C and some class D β-lactamases. A few also bind PBP2, conferring direct antibacterial activity and a β-lactamase-independent 'enhancer' effect, potentiating β- lactams targeting PBP3. We tested a novel DBO, zidebactam, combined with cefepime. Methods: CLSI agar dilution MICs were determined with cefepime/zidebactam in a chequerboard format. Bactericidal activity was also measured. Results:
Zidebactam MICs were ≤2 mg/L (mostly 0.12-0.5 mg/L) for most Escherichia coli , Klebsiella , Citrobacter and Enterobacter spp., but were >32 mg/L for Proteeae, most Serratia and a few E. coli , Klebsiella and Enterobacter/Citrobacter . The antibacterial activity of zidebactam dominated chequerboard studies for Enterobacteriaceae, but potentiation of cefepime was apparent for zidebactam-resistant isolates with class A and C enzymes, illustrating β-lactamase inhibition. Overall, cefepime/zidebactam inhibited almost all Enterobacteriaceae with AmpC, ESBL, K1, KPC and OXA-48-like β-lactamases at 1 + 1 mg/L and also 29 of 35 isolates with metallo-carbapenemases, including several resistant to zidebactam alone. Zidebactam MICs for 36 of 50 Pseudomonas aeruginosa were 4-16 mg/L, and the majority of AmpC, metallo-β-lactamase-producing and cystic fibrosis isolates were susceptible to cefepime/zidebactam at 8 + 8 mg/L. Zidebactam MICs for Acinetobacter baumannii and Stenotrophomonas maltophilia were >32 mg/L; potentiation of cefepime was frequent for S. maltophilia , but minimal for A. baumannii . Kill curve results largely supported MICs. Conclusions:
Zidebactam represents a second triple-action DBO following RG6080, with lower MICs for Enterobacteriaceae and P. aeruginosa . Clinical evaluation of cefepime/zidebactam must critically evaluate the reliance that can be placed on this direct antibacterial activity and on the enhancer effect as well as β-lactamase inhibition.
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Authors | David M Livermore, Shazad Mushtaq, Marina Warner, Anna Vickers, Neil Woodford |
Journal | The Journal of antimicrobial chemotherapy
(J Antimicrob Chemother)
Vol. 72
Issue 5
Pg. 1373-1385
(05 01 2017)
ISSN: 1460-2091 [Electronic] England |
PMID | 28158732
(Publication Type: Journal Article)
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Copyright | © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: [email protected]. |
Chemical References |
- Anti-Bacterial Agents
- Azabicyclo Compounds
- Cephalosporins
- Cyclooctanes
- Piperidines
- beta-Lactamase Inhibitors
- zidebactam
- Cefepime
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Topics |
- Anti-Bacterial Agents
(pharmacology)
- Azabicyclo Compounds
(pharmacology)
- Cefepime
- Cephalosporins
(pharmacology)
- Citrobacter
(drug effects)
- Cyclooctanes
(pharmacology)
- Enterobacteriaceae
(drug effects)
- Enterobacteriaceae Infections
(microbiology)
- Escherichia coli
(drug effects)
- Gram-Negative Bacteria
(drug effects)
- Humans
- Klebsiella
(drug effects)
- Microbial Sensitivity Tests
- Piperidines
(pharmacology)
- beta-Lactamase Inhibitors
(pharmacology)
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