title: Activity of carbapenems with ME1071 (disodium 2,3-diethylmaleate) against Enterobacteriaceae and Acinetobacter spp. with carbapenemases, including NDM enzymes.
abstract: OBJECTIVE
  ME1071 is a maleic acid that inhibits metallo-β-lactamases (MBLs). We examined its ability to potentiate different carbapenems against MBL-producing Enterobacteriaceae in relation to its inhibition kinetics.
  
  
  METHODS
  Enterobacteriaceae and Acinetobacter isolates with IMP, VIM and NDM MBLs were tested; bacteria with other types of carbapenem resistance were used as controls. Chequerboard titrations were performed by CLSI agar dilution, carbapenemases were cloned into pET-28a(+) and purified by column chromatography, and kinetic parameters were determined by spectrophotometry.
  
  
  RESULTS
  The key findings were: (i) the MICs of carbapenems varied widely among isolates with the same carbapenemase, but those with the NDM types were generally the most resistant; (ii) biapenem was the carbapenem least compromised by all MBL types, owing to weaker kinetic efficiency (k(cat)/K(m)) for hydrolysis, contingent on lower affinity (higher K(m)); (iii) MBLs were the only carbapenemases inhibited by ME1071, confirming its specificity of action; and (iv) irrespective of the partner carbapenem, synergy with ME1071 was least for organisms with NDM MBLs and most for those with IMP types, correlating with ME1071 having weakest affinity (highest K(i)) for NDM-1 and strongest affinity for IMP-1.
  
  
  CONCLUSIONS
  ME1071 reduced the MICs of carbapenems for bacteria with NDM-1 enzyme though synergy was weaker than for bacteria with IMP and VIM metallo-enzymes; this correlated with ME1071 having weaker affinity for NDM-1 than IMP-1 and VIM-2. As the weakest MBL substrate carbapenem, biapenem was the easiest to protect.
authors.affiliation: Antibiotic Resistance Monitoring and Reference Laboratory, Health Protection Agency-Colindale, London NW9 5EQ, UK. d.livermore@uea.ac.uk
authors.forename: David M
authors.initials: DM
authors.lastname: Livermore
authors.forename: Shazad
authors.initials: S
authors.lastname: Mushtaq
authors.forename: Akihiro
authors.initials: A
authors.lastname: Morinaka
authors.forename: Takashi
authors.initials: T
authors.lastname: Ida
authors.forename: Kazunori
authors.initials: K
authors.lastname: Maebashi
authors.forename: Russell
authors.initials: R
authors.lastname: Hope
mesh_terms: D000150:Acinetobacter / Q000187:drug effects* / Q000201:enzymology; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015780:Carbapenems / Q000008:administration & dosage*; D004357:Drug Synergism; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D006801:Humans; D008298:Maleates / Q000008:administration & dosage* / Q000737:chemistry; D008826:Microbial Sensitivity Tests / Q000379:methods; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D015780:Carbapenems; D004791:Enzyme Inhibitors; D008298:Maleates; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases; C063912:carbapenemase; C014476:diethyl maleate