Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry as a confirmation procedure in internationally recognised standard test methods for Cronobacter sakazakii

Abstract

Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) is accepted as a reliable, rapid technique for confirming microorganism identity. In this study, MALDI-TOF MS was evaluated for replacement of the current biochemical phenotype confirmation steps in the International Standardisation Organisation (ISO) and US Food and Drug Administration (USFDA) methods for the detection of Cronobacter in dairy products, with particular emphasis on routine testing regimes. Successful detection and correct identification of Cronobacter sakazakii strains were achieved directly from enrichment broths (88%) and on agar plates (100%) at the end of each standard test method. Confirmation using MALDI-TOF MS analysis in the ISO and USFDA methods for Cronobacter detection in dairy products would reduce the time taken for these tests in a routine dairy testing laboratory by between 24 and 72 h. MALDI-TOF MS confirmation of Cronobacter in dairy products is therefore proposed for adoption into these internationally recognised standard test methods.