Differentiation of Cronobacter spp. by tryptic digestion of the cell suspension followed by MALDI-TOF MS analysis.
Intact cell MALDI-TOF mass spectrometry is a rapid tool for the identification and classification of microorganisms, now widely used even in clinical laboratories. However, its distinctive power is not sufficient for some closely-related species. The genus Cronobacter, formerly known as Enterobacter sakazakii, contains such species. In this work, a new method for the differentiation of five Cronobacter species is presented involving the tryptic digestion of cytoplasmatic proteins followed by MALDI mass spectrometry analysis. A database was developed for use in Bruker Biotyper software including 52 reference spectra and tested on a set of 45 samples with an overall accuracy of about 80%. The possibility of measurement automation and the short time and low cost requirements of this method compared to those of biochemical tests or PCR methods make it a supplementary option to intact cell MALDI, providing additional information about the differentiation of problematic species.
Institute of Chemical Technology in Prague, Technická 5, 166 28 Prague 6, Czech Republic; Institute of Microbiology, AS CR, v.v.i., Vídeňská 1083, 142 20 Prague 4, Czech Republic. Electronic address: krasnyl@vscht.cz.
Lukáš
L
Krásný
Institute of Chemical Technology in Prague, Technická 5, 166 28 Prague 6, Czech Republic.
Eva
E
Rohlová
Institute of Chemical Technology in Prague, Technická 5, 166 28 Prague 6, Czech Republic.
Helena
H
Růžičková
Institute of Chemical Technology in Prague, Technická 5, 166 28 Prague 6, Czech Republic.
Jiří
J
Santrůček
Institute of Chemical Technology in Prague, Technická 5, 166 28 Prague 6, Czech Republic.
Radovan
R
Hynek
Institute of Chemical Technology in Prague, Technická 5, 166 28 Prague 6, Czech Republic.
Igor
I
Hochel
D015373:Bacterial Typing Techniques / Q000379:methods*; D001431:Bacteriological Techniques / Q000379:methods; D059126:Cronobacter / Q000302:isolation & purification*; D044083:Cronobacter sakazakii / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000379:methods; D012984:Software; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
Biotyper; Cronobacter; MALDI-TOF; Mass spectrometry; Trypsin