Evaluation of a new chromogenic medium, chromID OXA-48, for recovery of carbapenemase-producing Enterobacteriaceae from patients at a university hospital in Turkey

Eur J Clin Microbiol Infect Dis. 2015 Mar;34(3):519-25. doi: 10.1007/s10096-014-2255-z. Epub 2014 Oct 12.

Abstract

The purpose of this study was to evaluate a new chromogenic medium, chromID OXA-48, for the isolation of carbapenemase-producing Enterobacteriaceae (CPE) directly from rectal swabs. chromID CARBA and chromID OXA-48 are two chromogenic media that have been commercialized for the isolation of CPE directly from clinical samples. Both media were evaluated alongside a broth enrichment method recommended by the CDC for isolation of CPE, with rectal swabs from 302 unique hospitalized patients at the Hacettepe University Hospital, Ankara, Turkey. A total of 33 patients (11 %) were found to be colonized with CPE using a combination of all methods, and all CPE produced OXA-48 carbapenemase. Klebsiella pneumoniae was by far the most dominant species of CPE and was isolated from 31 patients. Culture on chromID OXA-48 offered the highest sensitivity (75.8 %) for detection of CPE compared with the other two methods (sensitivity for both other methods was 57.6 %) and also offered the highest specificity (99.3 %). However, a combination of methods (either chromID OXA-48 plus CDC method or chromID OXA-48 plus chromID CARBA) was necessary to achieve an acceptable sensitivity (90.9 %). For isolation of CPE, in a setting where OXA-48 carbapenemase is the dominant type of carbapenemase, chromID OXA-48 is a highly useful medium but using a combination of methods is optimal for adequate detection. The combined use of two chromogenic media offered acceptable sensitivity (90.9 %) and the highest specificity (98.5 %) and also allowed for isolation of CPE within 18-20 h.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / analysis*
  • Bacteriological Techniques / methods*
  • Chromogenic Compounds / metabolism
  • Color
  • Culture Media / chemistry*
  • Enterobacteriaceae / enzymology*
  • Enterobacteriaceae / isolation & purification*
  • Enterobacteriaceae Infections / microbiology*
  • Hospitals, University
  • Humans
  • Rectum / microbiology
  • Sensitivity and Specificity
  • Turkey
  • beta-Lactamases / analysis*

Substances

  • Bacterial Proteins
  • Chromogenic Compounds
  • Culture Media
  • beta-Lactamases
  • carbapenemase