INTRODUCTION: During the past few years, several studies describing direct identification of bacteria from blood culture using mass spectrometry have been published. These methods cannot, however, be easily integrated into a common laboratory workflow because of the high hands-on time they require. In this paper, we propose a new method of identification with a short hands-on time and a turnaround time shorter than 15min. MATERIALS AND METHODS: Positive blood bottles were homogenised and 600μL of blood were transferred to an Eppendorf tube where 600μL of lysis buffer were added. After homogenisation, a centrifugation step of 4min at 10,500g was performed and the supernatant was discarded. The pellet was then washed and loaded in quadruplicate into wells of a Vitek® MS-DS plate. Each well was covered with a saturated matrix solution and a MALDI-TOF mass spectrometry analysis was performed. Species were identified using the software Myla 3.2.0-2. RESULTS: We analysed 266 positive blood culture bottles. A microorganism grew in 261 cultures, while five bottles remained sterile after 48h of incubation in subculture. Our method reaches a probability of detection at the species level of 77.8% (203/261) with a positive predictive value of 99.5% (202/203). CONCLUSION: We developed a new method for the identification of microorganisms using mass spectrometry, directly performed from a positive blood culture. This method has short hands-on time and turnaround time and can easily take place in the workflow of a laboratory, with comparable results in performance with other methods reported in the literature.
INTRODUCTION: During the past few years, several studies describing direct identification of bacteria from blood culture using mass spectrometry have been published. These methods cannot, however, be easily integrated into a common laboratory workflow because of the high hands-on time they require. In this paper, we propose a new method of identification with a short hands-on time and a turnaround time shorter than 15min. MATERIALS AND METHODS: Positive blood bottles were homogenised and 600μL of blood were transferred to an Eppendorf tube where 600μL of lysis buffer were added. After homogenisation, a centrifugation step of 4min at 10,500g was performed and the supernatant was discarded. The pellet was then washed and loaded in quadruplicate into wells of a Vitek® MS-DS plate. Each well was covered with a saturated matrix solution and a MALDI-TOF mass spectrometry analysis was performed. Species were identified using the software Myla 3.2.0-2. RESULTS: We analysed 266 positive blood culture bottles. A microorganism grew in 261 cultures, while five bottles remained sterile after 48h of incubation in subculture. Our method reaches a probability of detection at the species level of 77.8% (203/261) with a positive predictive value of 99.5% (202/203). CONCLUSION: We developed a new method for the identification of microorganisms using mass spectrometry, directly performed from a positive blood culture. This method has short hands-on time and turnaround time and can easily take place in the workflow of a laboratory, with comparable results in performance with other methods reported in the literature.
Authors: Ryan J McGuire; Sean C Yu; Philip R O Payne; Albert M Lai; M Cristina Vazquez-Guillamet; Marin H Kollef; Andrew P Michelson Journal: Antimicrob Agents Chemother Date: 2021-06-17 Impact factor: 5.191
Authors: Johannes Forster; Britta Kohlmorgen; Julian Haas; Philipp Weis; Lukas Breunig; Doris Turnwald; Boris Mizaikoff; Christoph Schoen Journal: PLoS One Date: 2022-04-28 Impact factor: 3.752