Diagnostic performance of the Xpert Carba-R assay for active surveillance of rectal carbapenemase-producing organisms in intensive care unit patients

Young Jin Ko, Jeeyong Kim, Ha Nui Kim, Soo-Young Yoon, Chae Seung Lim, Chang Kyu Lee

Research output: Contribution to journalArticle


Background: There are growing concerns regarding the spread of carbapenemase-producing organisms (CPOs) among patients in long-term care facilities (LTCFs) and hospitals in South Korea. We have established a screening protocol for the detection of CPOs in high-risk patients upon admission to intensive care units (ICUs). The diagnostic performance of the Xpert Carba-R assay was compared to that of rectal culture for CPO detection in high-risk patients upon ICU admission. Methods: A total of 408 consecutive rectal swabs were obtained from December 2016 to December 2017. CPO screening was performed using the Xpert Carba-R assay (Cepheid, Sunnyvale, CA, USA). When a carbapenemase gene was detected, additional rectal swabs were incubated overnight and inoculated on chromID CARBA medium (bioMérieux, Marcy l'Etoile, France). Bacterial carbapenemase genes, including bla KPC, bla NDM, bla VIM, bla IMP-1, and bla OXA-48, were confirmed by conventional PCR. The diagnostic performance of the Carba-R assay was ascertained based on the culture results. Results: The prevalence of CPO carriage was 7.4% according to the Carba-R assay and 3.7% according to rectal culture. The median Ct values of IMP-1 and KPC were significantly different (35.2 vs. 26.6, P = 0.0143). The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the Carba-R assay were 100.0% (95% confidence interval [CI], 78.2-100.0), 96.7% (94.4-98.2), 53.6% (40.4-66.4) and 100.0% (99.0-100.0), respectively. Conclusions: We demonstrated the prevalence of CPO carriage in high-risk patients upon ICU admission and evaluated the diagnostic performance of the Carba-R assay. The combined use of the Xpert Carba-R assay and culture produces rapid and reliable results for the active surveillance of rectal CPO in ICU patients.

Original languageEnglish
Article number127
JournalAntimicrobial resistance and infection control
Issue number1
Publication statusPublished - 2019 Jul 29



  • Carbapenemase
  • Chromogenic culture
  • Gram-negative bacteria
  • Intensive care unit
  • Molecular methods
  • Surveillance
  • Xpert Carba-R assay

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)

Cite this