Sepsis is a major cause of death worldwide among nonhospitalized people and hospitalized patients. A wide range of pathogens are involved, and the correct identification and correct antimicrobial therapy are critical to ensure optimal clinical outcomes. With the recent introduction of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), rapid identification of bacteria and fungi is now possible. The purpose of this study was to develop a rapid technique for identifying organisms in positive blood cultures using the Vitek MS system (bioMérieux). This technique is a lysis centrifugation method which involves a four-step washing and centrifugation procedure. A total of 253 positive monomicrobial blood cultures (Bactec Plus aerobic, anaerobic, and pediatric bottles) were tested using the Vitek MS system (KnowledgeBase version 2.0), with 92.1% and 88.1% of organisms overall being identified to the genus level and the species level, respectively. Of 161 Gram-positive bacterial isolates, 95.7% and 90.1% were identified to the genus level and the species level, respectively; of 92 Gram-negative bacterial isolates, 84.7% and 83.7% were identified to the genus level and the species level, respectively. The results obtained using this method demonstrate that the Vitek MS system can be used for rapid and effective identification of bacteria from positive blood cultures within 30 to 45 min after the positive signal has been provided by the Bactec FX blood culture system (Becton, Dickinson). This will lead to faster administration of the appropriate antimicrobial therapy and increase the chances for optimal clinical outcomes for patients. Sepsis is one of the most common causes of death in seriously ill patients. About 18 million cases occur worldwide each year, with a mortality rate of around 30% (1). The first 24 h of patient care is critical for determining and administering the appropriate antimicrobial therapy, and mortality rates increase by approximately 7% for every hour a septic patient remains untreated or receives inappropriate antimicrobial therapy (2). The present turnaround time for the identification of causative organisms, from the time of positive results from the blood culture system, is about 18 to 24 h.Faster identification technology, such as matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), provides faster and more accurate identification of bacteria and fungi. The objective of this work was to use the Vitek MS system (bioMérieux) to attempt to identify bacteria directly from positive blood culture bottles within 30 to 45 min after the time of the positive signal from the Bactec FX (Becton, Dickinson) blood culture system. Various methods and techniques (both commercial and in-house) have been used for direct identification of microorganisms from positive blood culture broths, for example, the Sepsityper kit (Bruker), the saponin method for bacterial extraction (3, 4), lysis centrifugation methods (5), and the serum separa...