title: Optimal turnaround time for direct identification of microorganisms by mass spectrometry in blood culture.
abstract: 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.
  
  
  
  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.
  
  
  
  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).
  
  
  
  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: Medical Laboratory, Cliniques du Sud Luxembourg, Arlon, Belgium. Electronic address: adrien.randazzo@gmail.com.
authors: Adrien
authors: A
authors: Randazzo
authors: Infectiology Department, Cliniques du Sud Luxembourg, Arlon, Belgium.
authors: Marc
authors: M
authors: Simon
authors: Medical Laboratory, Cliniques du Sud Luxembourg, Arlon, Belgium.
authors: Pierre
authors: P
authors: Goffinet
authors: Medical Laboratory, Cliniques du Sud Luxembourg, Arlon, Belgium.
authors: Jean-François
authors: JF
authors: Classen
authors: Medical Laboratory, Cliniques du Sud Luxembourg, Arlon, Belgium.
authors: Nicolas
authors: N
authors: Hougardy
authors: Internal Medicine Department, Cliniques du Sud Luxembourg, Arlon, Belgium.
authors: Pascal
authors: P
authors: Pierre
authors: Surgery Department, Cliniques du Sud Luxembourg, Arlon, Belgium.
authors: Philippe
authors: P
authors: Kinzinger
authors: Surgery Department, Cliniques du Sud Luxembourg, Arlon, Belgium.
authors: Etienne
authors: E
authors: Mauel
authors: Medical Laboratory, Cliniques du Sud Luxembourg, Arlon, Belgium.
authors: Jean-Sébastien
authors: JS
authors: Goffinet
mesh_terms: D001419:Bacteria / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification*; D001424:Bacterial Infections / Q000097:blood / Q000382:microbiology; D001431:Bacteriological Techniques / Q000379:methods*; D001769:Blood / Q000382:microbiology; D000071997:Blood Culture / Q000379:methods*; D018929:Cell Culture Techniques; D003470:Culture Media; D007753:Laboratories; D013058:Mass Spectrometry / Q000379:methods*; D011336:Probability; D012680:Sensitivity and Specificity; D012984:Software; D013997:Time Factors
chemical_list: D003470:Culture Media
keywords: Bacterial identification; Blood culture; MALDI-TOF MS; Vitek MS