title: Phenotypic detection of the cfiA metallo-β-lactamase in Bacteroides fragilis with the meropenem-EDTA double-ended Etest and the ROSCO KPC/MBL Confirm Kit.
abstract: To investigate the performance of the meropenem and imipenem double-ended Etest ± EDTA and the tablet-based (meropenem and meropenem + dipicolinic acid) KPC/MBL Confirm Kit to detect cfiA metallo-β-lactamase (MBL) in Bacteroides fragilis.
  
  
  
  Well-characterized B. fragilis isolates, most from previously published studies, harbouring the cfiA gene and covering a wide range of meropenem MICs were included (n = 21).
  
  
  
  The imipenem double-ended Etest showed an indeterminate result in 95% of the included isolates with the cfiA gene (20 of 21), whereas the meropenem double-ended Etest gave an MIC ratio ≥8 (positive test) with all the isolates. All isolates that were meropenem intermediate or resistant had a zone diameter difference ≥6 mm with the KPC/MBL Confirm Kit.
  
  
  
  The meropenem double-ended Etest and not imipenem should be preferred for phenotypic detection of MBLs in B. fragilis. The KPC/MBL Confirm Kit could be an alternative with isolates that are meropenem intermediate or resistant (MIC >2 mg/L).
authors: Department of Clinical Microbiology, Odense University Hospital, Odense, Denmark.
authors: Simon A
authors: SA
authors: Schwensen
authors: Department of Clinical Microbiology, Odense University Hospital, Odense, Denmark.
authors: Ziyap
authors: Z
authors: Acar
authors: Department of Clinical Microbiology, Odense University Hospital, Odense, Denmark.
authors: Thomas V
authors: TV
authors: Sydenham
authors: Department of Clinical Microbiology, Central Hospital, Växjo, Sweden.
authors: Åsa C
authors: ÅC
authors: Johansson
authors: Department of Clinical Microbiology, Odense University Hospital, Odense, Denmark ujustesen@health.sdu.dk.
authors: Ulrik S
authors: US
authors: Justesen
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism*; D001426:Bacterial Proteins / Q000032:analysis*; D001441:Bacteroides fragilis / Q000201:enzymology*; D052978:Disk Diffusion Antimicrobial Tests / Q000379:methods*; D004492:Edetic Acid / Q000378:metabolism*; D000077731:Meropenem; D011933:Reagent Kits, Diagnostic; D013845:Thienamycins / Q000378:metabolism*; D001618:beta-Lactamases / Q000032:analysis*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D011933:Reagent Kits, Diagnostic; D013845:Thienamycins; D004492:Edetic Acid; D001618:beta-Lactamases; C063912:carbapenemase; D000077731:Meropenem