title: A combined disc method with resazurin agar plate assay for early phenotypic screening of KPC, MBL and OXA-48 carbapenemases among Enterobacteriaceae.
abstract: OBJECTIVE
  To validate a combined disc method along with resazurin chromogenic agar for early screening and differentiation of Klebsiella pneumoniae carbapenemase, metallo-β-lactamase and OXA-48 carbapenemase-producing Enterobacteriaceae.
  
  
  RESULTS
  The combined disc test comprising of meropenem alone and with EDTA, phenylboronic acid or both EDTA and phenylboronic acid, and temocillin alone were evaluated with the resazurin chromogenic agar plate assay against a total of 86 molecularly confirmed Enterobacteriaceae clinical isolates (11 metallo-β-lactamases, eight Kl. pneumoniae carbapenemases, 11 OXA-48, 32 AmpC and 15 extended-spectrum-β-lactamase producers and nine co-producers of extended-spectrum-β-lactamase and AmpC). The inhibition zone diameters were measured and interpreted at 7 h for the presence of carbapenemase. All carbapenemase producers were phenotypically distinguished by this assay with 100% sensitivity and specificity.
  
  
  CONCLUSIONS
  This early phenotypic method is very simple, inexpensive, and reliable in the detection and differentiation of carbapenemase-producing Enterobacteriaceae. It could be exploited in any microbiological laboratory for diagnosis of these recalcitrant bacteria.
  
  
  CONCLUSIONS
  This assay poses excellent performance in discrimination of Kl. pneumoniae carbapenemase, metallo-β-lactamase and OXA-48 carbapenemases within 7 h, which is much faster than conventional disc diffusion methods. The rapid detection could help clinicians screen patients, control infection and provide epidemiological surveillance.
authors.affiliation: School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK.|School of Pharmacology, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, Thailand.
authors.forename: Y
authors.initials: Y
authors.lastname: Teethaisong
authors.affiliation: School of Pharmacology, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, Thailand.
authors.forename: G
authors.initials: G
authors.lastname: Eumkeb
authors.affiliation: School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK.
authors.forename: I
authors.initials: I
authors.lastname: Nakouti
authors.affiliation: School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK.
authors.forename: K
authors.initials: K
authors.lastname: Evans
authors.affiliation: School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK.
authors.forename: G
authors.initials: G
authors.lastname: Hobbs
mesh_terms: D000362:Agar; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000032:analysis*; D004755:Enterobacteriaceae / Q000145:classification / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods*; D010078:Oxazines; D010121:Oxytocin / Q000031:analogs & derivatives; D014966:Xanthenes; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000032:analysis*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D010078:Oxazines; D014966:Xanthenes; C005843:resazurin; D010121:Oxytocin; C015692:oxytocin, Asp(5)-; D000362:Agar; D001618:beta-Lactamases; C063912:carbapenemase
keywords: Enterobacteriaceae; carbapenemase; combined disc; phenotypic test; resazurin