Multicenter evaluation of the xpert carba-R assay for detection of carbapenemase genes in gram-negative isolates

Maria M. Traczewski, Edoardo Carretto, Rafael Canton, Nicholas M. Moore, Flavia Brovarone, Paola Nardini, Rosa Visiello, María García-Castillo, Patricia Ruiz-Garbajosa, Marta Tato

Research output: Contribution to journalArticlepeer-review


This multicenter study evaluated the performance of the Cepheid Xpert Carba-R assay, a qualitative PCR test designed for the rapid detection of blaKPC, blaNDM, blaVIM, blaIMP, and blaOXA-48 carbapenem resistance genes from bacterial isolates grown on blood agar or MacConkey agar. The results were compared to those obtained from bidirectional DNA sequence analysis of nucleic acid extracted from pure colonies. Isolates of Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii that tested as either intermediate or resistant to a carbapenem antibiotic were analyzed. A total of 467 isolates were evaluated, including prospectively collected clinical isolates, frozen isolates, and a group of contrived broth specimens sent by a central reference laboratory. The assay was run on the GeneXpert platform and took 48 min, with less than 1 min of hands-on time. Compared to the results of the reference methods, the overall sensitivity of the assay was 100% (95% confidence interval [CI], 99.0 to 100%) for isolates grown on both blood and MacConkey agars. Overall specificity was 98.1% (95% CI, 93.1 to 99.8%) and 97.1% (95% CI, 91.7 to 99.4%) for blood and MacConkey agars, respectively. This platform, previously demonstrated to be effective for the detection of carbapenemase genes in rectal swabs, is also adequate for the detection of these genes in bacterial colonies isolated from blood and MacConkey agars.

Original languageEnglish
Article numbere00272-18
JournalJournal of Clinical Microbiology
Issue number8
Publication statusPublished - Aug 1 2018
Externally publishedYes


  • Bacterial isolates
  • Carbapenemase detection
  • Gram-negative bacteria
  • Molecular methods
  • Multidrug resistance
  • Surveillance
  • Surveillance studies
  • Xpert Carba-R assay

ASJC Scopus subject areas

  • Microbiology (medical)


Dive into the research topics of 'Multicenter evaluation of the xpert carba-R assay for detection of carbapenemase genes in gram-negative isolates'. Together they form a unique fingerprint.

Cite this