Development and performance evaluation of a biochemical kit for identification of Enterobacteriaceae based on numerical identification method

Abstract:

[Background] Bacteria of Enterobacteriaceae are the main pathogens of foodborne and clinical infections, posing a threat to human and animal health. The numerical identification method using API 20E as the “gold standard” is one of the main identification methods for Enterobacteriaceae. However, the existing numerical identification methods have problems such as laborious sample addition, low accuracy, and high prices. [Objective] To develop a semi-automatic, high-precision, and low-cost biochemical kit for identifying the bacteria of Enterobacteriaceae based on the numerical identification method. [Methods] On the basis of the theoretical model and supporting software of the numerical identification system for Enterobacteriaceae established by our team, we designed and optimized 24 biochemical matrix trace formulations. Furthermore, a semi-automatic freeze-drying identification strip was developed. Using the commercialized numerical identification strip API 20E, MALDI-TOF MS, and 16S rRNA gene sequencing as the controls, we evaluated the performance of the developed biochemical kit that integrated semi-automatic biochemical identification strips and online analysis software. [Results] The biochemical spectra of 458 strains of Enterobacteriaceae were obtained, with the overall identification accuracy of 98.5% at the genus level and 96.5% at the species level. The kit only needed twice sample addition to obtain the identification results, with the price only 4.46% that of API 20E. The shelf life of the product was 7 days, and the biochemical experiments had repeatability. [Conclusion] We develop a semi-automatic biochemical kit for identification of Enterobacteriaceae based on the numerical identification method, which has simple operation, a low cost, and high accuracy. This study provides technical support for the identification of Enterobacteriaceae and the development of biochemical products for numerical identification of other families and genera of bacteria.