2. Academic Validation
  3. Nacubactam Enhances Meropenem Activity against Carbapenem-Resistant Klebsiella pneumoniae Producing KPC

Nacubactam Enhances Meropenem Activity against Carbapenem-Resistant Klebsiella pneumoniae Producing KPC

  • Antimicrob Agents Chemother. 2019 Jul 25;63(8):e00432-19. doi: 10.1128/AAC.00432-19.
Melissa D Barnes 1 2,  Magdalena A Taracila 1 2,  Caryn E Good 2 3,  Saralee Bajaksouzian 2 3,  Laura J Rojas 1 2 4,  David van Duin 5,  Barry N Kreiswirth 6,  Michael R Jacobs 2 3,  Andreas Haldimann 7,  Krisztina M Papp-Wallace 1 2 8,  Robert A Bonomo 9 2 8 4 10 11 12 13
Affiliations

Affiliations

  • 1 Louis Stokes Cleveland VA Medical Center, Research Service, Cleveland, Ohio, USA.
  • 2 Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.
  • 3 Department of Pathology, Cleveland Medical Center Hospitals, Cleveland, Ohio, USA.
  • 4 Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio, USA.
  • 5 University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA.
  • 6 Rutgers University, Public Health Research Institute Tuberculosis Center, New Jersey Medical School, Newark, New Jersey, USA.
  • 7 Roche Pharma Research and Early Development, Immunology, Infectious Diseases and Ophthalmology, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland.
  • 8 Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio, USA.
  • 9 Louis Stokes Cleveland VA Medical Center, Research Service, Cleveland, Ohio, USA robert.bonomo@va.
  • 10 Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA.
  • 11 Department of Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, Ohio, USA.
  • 12 CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, Ohio, USA.
  • 13 Geriatric Research Education and Clinical Centers (GRECC), Louis Stokes Cleveland Department of Veterans Affairs, Cleveland, Ohio, USA.
PMID: 31182530 DOI: 10.1128/AAC.00432-19
Abstract

Carbapenem-resistant Enterobacteriaceae (CRE) are resistant to most Antibiotics, making CRE infections extremely difficult to treat with available agents. Klebsiella pneumoniae carbapenemases (KPC-2 and KPC-3) are predominant carbapenemases in CRE in the United States. Nacubactam is a bridged diazabicyclooctane (DBO) β-lactamase inhibitor that inactivates class A and C β-lactamases and exhibits intrinsic Antibiotic and β-lactam "enhancer" activity against Enterobacteriaceae In this study, we examined a collection of meropenem-resistant K. pneumoniae isolates carrying blaKPC-2 or blaKPC-3; meropenem-nacubactam restored susceptibility. Upon testing isogenic Escherichia coli strains producing KPC-2 variants with single-residue substitutions at important Ambler class A positions (K73, S130, R164, E166, N170, D179, K234, E276, etc.), the K234R variant increased the meropenem-nacubactam MIC compared to that for the strain producing KPC-2, without increasing the meropenem MIC. Correspondingly, nacubactam inhibited KPC-2 (apparent Ki [Ki app] = 31 ± 3 μM) more efficiently than the K234R variant (Ki app = 270 ± 27 μM) and displayed a faster acylation rate (k2/K), which was 5,815 ± 582 M-1 s-1 for KPC-2 versus 247 ± 25 M-1 s-1 for the K234R variant. Unlike avibactam, timed mass spectrometry revealed an intact sulfate on nacubactam and a novel peak (+337 Da) with the K234R variant. Molecular modeling of the K234R variant showed significant catalytic residue (i.e., S70, K73, and S130) rearrangements that likely interfere with nacubactam binding and acylation. Nacubactam's aminoethoxy tail formed unproductive interactions with the K234R variant's active site. Molecular modeling and docking observations were consistent with the results of biochemical analyses. Overall, the meropenem-nacubactam combination is effective against carbapenem-resistant K. pneumoniae Moreover, our data suggest that β-lactamase inhibition by nacubactam proceeds through an alternative mechanism compared to that for avibactam.

Keywords

K234R; KPC; diazabicyclooctane (DBO); nacubactam; β-lactam; β-lactamase.

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