Direct identification of bacteria from positive BacT/ALERT blood culture bottles using matrix-assisted laser desorption ionization–time-of-flight mass spectrometry

•We establish a low-cost method for identification of bacteria from blood bottles.•The method is quick, providing results in less than 20 minutes per sample.•Identification rates are high compared to most methods found in the literature.•Significant time savings could impact clinical management of antibiotic treatment.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry is a fast and robust method for the identification of bacteria. In this study, we evaluate the performance of a laboratory-developed lysis method (LDT) for the rapid identification of bacteria from positive BacT/ALERT blood culture bottles. Of the 168 positive bottles tested, 159 were monomicrobial, the majority of which were Gram-positive organisms (61.0% versus 39.0%). Using a cut-off score of ≥1.7, 80.4% of the organisms were correctly identified to the species level, and the identification rate of Gram-negative organisms (90.3%) was found to be significantly greater than that of Gram-positive organisms (78.4%). The simplicity and cost-effectiveness of the LDT enable it to be fully integrated into the routine workflow of the clinical microbiology laboratory, allowing for rapid identification of Gram-positive and Gram-negative bacteria within an hour of blood culture positivity.