Evaluation of presumptive identification of Enterobacterales using CHROMagar Orientation medium and rapid biochemical tests

Hirofumi Ohtaki, Akifumi Takahashi, Ayumi Niwa, Jun Yonetamari, Asami Nakayama, Tomokazu Kuchibiro, Hirotoshi Ohta, Hiroyasu Ito, Hisashi Baba, Nobuo Murakami, Kiyofumi Ohkusu

Research output: Contribution to journalArticlepeer-review


Background: The use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry is gradually spreading among large-scale laboratories; however, this method is impractical for small-scale laboratories. In laboratories without access to these rapid identification methods, problems related to them remain unsolved. In this study, we aimed to develop a rapid and inexpensive method to presumptively identify Enterobacterales using CHROMagar Orientation medium. Methods: The algorithm for presumptive identification of Enterobacteriaceae using CHROMagar Orientation medium was based on our previous studies. Modified property tests for indole, lysine decarboxylase, ornithine decarboxylase, and hydrogen sulfide were performed to evaluate the differentiation of the bacterial species. Results: Using the type strains and clinical isolates, it was possible to conduct the property tests at a low cost, within 4 hours. The spot indole test was performed without any nonspecific reactions for the bacteria forming colored colonies. The presumptive identification of bacteria was thereby possible within 24 hours after specimen submission. Conclusion: All these results suggest that the rapid presumptive identification of Enterobacterales is possible with this new identification method using CHROMagar Orientation medium. This is therefore a prompt and economical method that can be used in routine laboratory work.

Original languageEnglish
Article numbere23453
JournalJournal of Clinical Laboratory Analysis
Issue number10
Publication statusPublished - 01-10-2020
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Immunology and Allergy
  • Hematology
  • Public Health, Environmental and Occupational Health
  • Clinical Biochemistry
  • Medical Laboratory Technology
  • Biochemistry, medical
  • Microbiology (medical)


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