Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF/MS)-Based Identification of Pathogens from Positive Blood Culture Bottles

Abstract

Since the expansion of commercial use of MALDI-TOF/MS instruments for the identification of bacteria from culture which has occurred over the past 5–8 years, techniques for the identification of bacteria directly from positive blood cultures have been developed (Lagace-Wiens et al., J Clin Microbiol 50:3324–3328, 2012; Martiny et al., Eur J Clin Microbiol Infect Dis 31:2269–2281, 2012; Moussaoui et al., Clin Microbiol Infect 16:1631–1638, 2010). These techniques have the potential to provide definitive identification of pathogens causing sepsis 18–48 h earlier than conventional methodologies, and implementation of these methods has been shown to impact morbidity and hospital costs in a positive way (Martiny et al., Clin Microbiol Infect 19:E568–E581, 2013; Loonen et al., Eur J Clin Microbiol Infect Dis 31:1575–1583, 2012). Although many methods for purification of bacterial cells have been developed, including differential centrifugation, centrifuge lysis, and preincubation on sold media (March-Rossello et al., Eur J Clin Microbiol Infect Dis 32:699–704, 2013; Saffert et al., Diagn Microbiol Infect Dis 73:21–26, 2012; Schubert et al., J Mol Diagn 13:701–706, 2011), we will describe the method by which intact bacterial cells are extracted from positive blood culture bottles using a commercially available kit (SepsiTyper™) which is based on the centrifuge lysis methodology (Lagace-Wiens et al., J Clin Microbiol 50:3324–3328, 2012; Buchan et al., J Clin Microbiol 50:346–352, 2012).