title: Evaluation of a chromogenic medium for detection of extended-spectrum-beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae strains.
abstract: BACKGROUND
  Because of the emergence and spread of extended-spectrum-beta-lactamase (ESBL)-producing strains which are resistant to many antibiotics, reliable detection of ESBL is very important for infection control. Several chromogenic media have been proposed for the detection of ESBL producers in addition to the conventional phenotypic and genotyping methods. The aim of the present study was to evaluate the performance of Brilliance ESBL agar (Oxoid; Thermo Fisher Scientific, UK), a selective chromogenic agar for the detection of ESBL-producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) strains.
  
  
  METHODS
  A total of 237 strains (143 ESBL producers (76 isolates of E. coli and 67 isolates of K. pneumoniae) and 94 non-ESBL producers (44 isolates of E. coli and 50 isolates of K. pneumoniae)) isolated from various clinical specimens were included in the study. Isolates were identified by conventional methods, Phoenix system (Becton Dickinson, USA), and mass spectrometry. ESBL confirmation was performed by phenotypical tests. A 10 microL aliquot of each isolate's 0.5 McFarland suspension was streaked onto Brilliance ESBL agar. All plates were incubated at 37 degrees C for 24 hours and then were interpreted for growth and colony color according to the manufacturer's recommendations. Identification and ESBL test results were used to calculate the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the medium evaluated at 24 hours.
  
  
  RESULTS
  The sensitivity, specificity, PPV, and NPV of the medium were 97.9%, 100%, 100%, and 96.9%, respectively, when considering only species specific colored colonies of the isolates.
  
  
  CONCLUSIONS
  Brilliance ESBL agar could provide a practical alternative to the traditional methods for the identification of ESBL producers.
authors.forename: Gozde
authors.initials: G
authors.lastname: Ongut
authors.forename: Aylin Erman
authors.initials: AE
authors.lastname: Daloglu
authors.forename: Betil Ozhak
authors.initials: BO
authors.lastname: Baysan
authors.forename: Duygu
authors.initials: D
authors.lastname: Daglar
authors.forename: Dilara
authors.initials: D
authors.lastname: Ogunc
authors.forename: Ali Osman
authors.initials: AO
authors.lastname: Sekercioglu
authors.forename: Dilek
authors.initials: D
authors.lastname: Colak
authors.forename: Filiz
authors.initials: F
authors.lastname: Gunseren
mesh_terms: D003470:Culture Media; D004926:Escherichia coli / Q000201:enzymology*; D007711:Klebsiella pneumoniae / Q000201:enzymology*; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D003470:Culture Media; D001618:beta-Lactamases