title: Validation of carbapenemase and extended-spectrum β-lactamase multiplex endpoint PCR assays according to ISO 15189.
abstract: OBJECTIVE
  To validate and accredit a set of three multiplex endpoint PCR assays, targeting the most important carbapenemase and minor extended-spectrum β-lactamase (ESBL) resistance genes, according to the international ISO 15189 particular requirements for the quality and competence of medical laboratories.
  
  
  METHODS
  Specific primers targeting ESBLs and carbapenemases were collected from the literature or designed internally. The multiplex PCRs were validated for sensitivity, specificity, intra- and inter-run reproducibility and accuracy by means of external quality control (EQC) using a collection of 137 characterized and referenced isolates. For each multiplex PCR assay, the presence of an extraction control ruled out false-negative results due to PCR inhibition or extraction faults. Amplicons were separated by capillary electrophoresis (QIAxcel system, Qiagen). The protocols and validation files were reviewed in the setting of an external audit conducted by the Belgian organization for accreditation (BELAC).
  
  
  RESULTS
  Sensitivity, specificity and reproducibility for each targeted gene were 100%. All isolates from the three EQC panels were correctly identified by each PCR assay (accuracy 100%). The validation files were controlled by BELAC, and the PCR protocols were accepted as accredited according to ISO 15189.
  
  
  CONCLUSIONS
  Three home-made multiplex PCRs targeting the major carbapenemases and four minor class A ESBL genes encountered in Gram-negative bacteria were accredited according to the ISO 15189 standards. This validation scheme could provide a useful model for laboratories aiming to accredit their own protocols.
authors.affiliation: Laboratory of Bacteriology, CHU UCL Mont-Godinne-Dinant, Yvoir, Belgium. pierre.bogaerts@uclouvain.be
authors.forename: P
authors.initials: P
authors.lastname: Bogaerts
authors.forename: R
authors.initials: R
authors.lastname: Rezende de Castro
authors.forename: R
authors.initials: R
authors.lastname: de Mendonça
authors.forename: T-D
authors.initials: TD
authors.lastname: Huang
authors.forename: O
authors.initials: O
authors.lastname: Denis
authors.forename: Y
authors.initials: Y
authors.lastname: Glupczynski
mesh_terms: D019075:Electrophoresis, Capillary / Q000379:methods; D006090:Gram-Negative Bacteria / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods* / Q000592:standards; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods* / Q000592:standards; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001618:beta-Lactamases
keywords: accreditation; minor ESBLs; molecular detection