Rapid Identification of Microorganisms Directly from Blood Culture Using an In-house Method by MALDI-TOF-MS

Background: Several commercial and in-house methods have been developed for identifying microorganisms directly from blood culture bottles (BCBs) using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS). Accurate and rapid identification can significantly reduce the reporting time for critical patients. Objectives: This study aimed to evaluate a simple, cost-effective method for detecting microorganisms from BCBs using the VITEK MS system and to compare the results with conventional blood culture and Gram staining methods. Methods: A total of 296 monomicrobial blood cultures were processed using an in-house extraction protocol and analyzed via the VITEK MS system. The results were compared to conventional culture methods, and statistical significance was assessed using chi-square analysis. Results: Gram-negative pathogens were identified with 92.0% accuracy, while Gram-positive pathogens were correctly identified in 66.4% of cases using the in-house method. Statistical analysis revealed that this difference was significant (P < 0.01), highlighting the method's higher reliability for Gram-negative bacteria. These results underscore the importance of refining protocols for Gram-positive bacteria to enhance overall diagnostic performance. Conclusions: The in-house method provided a cost-effective and feasible alternative for routine laboratory settings. While identification was highly successful for Gram-negative bacteria, further refinement is needed to improve accuracy for Gram-positive bacteria.