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

Abstract

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.

Development and evaluation of a colorimetric LAMP-based biosensor for rapid detection of a nosocomial infection agent, Citrobacter freundii

“…Prompt and accurate identification of C. freundii is essential for effective implementation of infection control approaches due to its pathogenicity in infants and adults. To date, C. freundii detection has been performed using currently available method, such as biochemical tests, culture-based methods, and PCR-based assays 14 , 16 , 30 , 31 . However, they need a long hands-on time leading to some inaccurate results, high costs, and high-tech facilities.…”

“…Rapid diagnosis of C. freundii as an infectious agent is vital for early treatment. There are various conventional methods for identifying C. freundii , such as culture-based biochemical tests; however, such methods are time-consuming and require a confirmatory test 14 – 16 . Therefore, molecular methods such as polymerase chain reaction (PCR) need to be developed due to appropriate sensitivity and high speed while they have some limitations namely the need for expensive equipment and specialized personnel 17 .…”