Abstract：Objective To establish a rapid bacterial identification and antimicrobial susceptibility testing assay in positive blood cultures, so as to provide insights into timely diagnosis and treatment of bloodstream infections. Methods A total of 1 154 blood culture samples were collected from inpatients in Zhejiang Hospital from February to May, 2022. The bacterial isolates were enriched and purified using improved separation gel method, and bacterial identification and antimicrobial susceptibility tests were performed using VITEK2 mass spectrometry system and VITEK2 Compact automated microbiology system. The accuracy of the new assay for bacterial identification and antimicrobial susceptibility tests was evaluated with the conventional VITEK 2 compact system as the standard. Results Of 1 154 blood culture specimens, the conventional VITEK 2 compact system detected 174 positives and 980 negatives. The new assay and the conventional VITEK 2 compact system identified consistent bacterial isolates in 165 out of 174 positive blood culture samples, and the accuracy of bacterial identification was 94.83% for the new assay, with a 99.21% accuracy for identifying Gram-negative bacteria and 82.22% for Gram-positive bacteria. Antimicrobial susceptibility tests were performed in 158 bacterial isolates, and the new assay presented a 90.17% accuracy, with a 90.27% accuracy for Gram-negative bacteria and 89.74% for Gram-positive bacteria. The conventional VITEK 2 compact system required 30 hours and longer to complete bacterial identification and antimicrobial susceptibility tests, and the new assay required 9 to 18 hours. Conclusions The new rapid bacterial identification and antimicrobial susceptibility testing assay shortens the time of bacterial culture, achieves rapid bacterial identification and antimicrobial susceptibility testing in blood culture specimens and has a high accuracy that meets clinical needs, which facilitates rapid diagnosis and treatment of bloodstream infections.
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