Evaluation of a Real-Time PCR Assay for Rectal Screening of OXA-48-producing Enterobacteriaceae in a General Intensive Care Unit of an Endemic Hospital

Diagn Microbiol Infect Dis. 2017 Jul;88(3):252-258. doi: 10.1016/j.diagmicrobio.2017.04.001. Epub 2017 Apr 6.


Carbapenemase-producing Enterobacteriaceae are increasing worldwide. Rectal screening for these bacteria can inform the management of infected and colonized patients, especially those admitted to intensive care units (ICUs). A laboratory developed, qualitative duplex real-time polymerase chain reaction assay for rapid detection of OXA-48-like and VIM producing Enterobacteriaceae, performed on rectal swabs, was designed and evaluated in an intensive care unit with endemic presence of OXA-48. During analytical assay validation, no cross-reactivity was observed and 100% sensitivity and specificity were obtained for both blaOXA-48-like and blaVIM in all spiked clinical samples. During the clinical part of the study, the global sensitivity and specificity of the real-time PCR assay for OXA-48 detection were 95.7% and 100% (P=0.1250), respectively, in comparison with culture; no VIM-producing Enterobacteriaceae were detected. Clinical features of patients in the ICU who were colonized or infected with OXA-48 producing Enterobacteriaceae, including outcome, were analyzed. Most had severe underlying conditions, and had risk factors for colonization with carbapenemase-producing Enterobacteriaceae before or during ICU admission, such as receiving previous antimicrobial therapy, prior healthcare exposure (including long-term care), chronic disease, immunosuppression and/or the presence of an intravascular catheter and/or mechanical ventilation device. The described real-time PCR assay is fast (~2-3hours, if DNA extraction is included), simple to perform and results are easy to interpret, features which make it applicable in the routine of clinical microbiology laboratories. Implementation in endemic hospitals could contribute to early detection of patients colonized by OXA-48 producing Enterobacteriaceae and prevention of their spread.

Keywords: Active surveillance; Carbapenemases; OXA-48; Real-time PCR; Vim.

Publication types

  • Evaluation Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Bacterial Proteins / genetics*
  • Carrier State / microbiology*
  • Enterobacteriaceae / enzymology*
  • Enterobacteriaceae / genetics
  • Enterobacteriaceae / isolation & purification
  • Enterobacteriaceae Infections / microbiology*
  • Female
  • Hospitals
  • Humans
  • Intensive Care Units
  • Male
  • Mass Screening / methods*
  • Middle Aged
  • Real-Time Polymerase Chain Reaction / methods*
  • Rectum / microbiology*
  • Sensitivity and Specificity
  • Time Factors
  • beta-Lactamases / genetics*


  • Bacterial Proteins
  • beta-Lactamases
  • carbapenemase