MALDI-TOF MS in microbiological diagnostics—identification of microorganisms and beyond (mini review)

Abstract

Few developments in microbiological diagnostics have had such a rapid impact on species level identification of microorganisms as matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Conventional differentiation methods rely on biochemical criteria and require additional pre-testing and lengthy incubation procedures. In comparison, MALDI-TOF MS can identify bacteria and yeast within minutes directly from colonies grown on culture plates. This radically new, methodically simple approach profoundly reduces the cost of consumables and time spent on diagnostics. The reliability and accuracy of the method have been demonstrated in numerous studies and different systems are already commercially available. Novel applications of the system besides microbial species level identification are also being explored. This includes identification of pathogens from positive blood cultures or directly from patient samples, such as urine. Currently, intriguing MALDI-TOF MS developments are being made regarding the phenotypic detection of certain antibiotic resistance mechanisms, e.g., β-lactamases and carbapenemases. This mini review provides an overview of the literature in the field and also includes our own data and experiences gathered from over 4 years of routine MALDI-TOF MS use in a university hospital's microbiological diagnostics facility.

Acinetobacter baumannii: biology and drug resistance — role of carbapenemases

“…According to the definition presented by Wieser and co-authors the method is based on the ionization of cocrystalized sample material by short laser pulses, and then so formed ions are accelerated and their time of flight is measured in a vacuum flight tube [105]. The application of MAL- www.fhc.viamedica.pl DI-TOF MS in the detection of carbapenemases is based on the identification of native imipenem and its natural metabolite, both molecules are identified according to their different masses.…”

Study on the effects of near-future ocean acidification on marine yeasts: a microcosm approach

“…Additionally, reference spectra of all isolates were compared among each other (MALDI BIOTYPER 3.0 software) and score values were assigned, describing the degree of similarity between different spectra. Values above 2.0 are considered species-level identifications, and values between 1.7 and 2.0 are considered genus-level identifications (Wieser et al 2012). Consequently, isolates displaying score values above 2.0 among each other were assigned to a MALDI-TOF MS class.…”

High-throughput, Highly Sensitive Analyses of Bacterial Morphogenesis Using Ultra Performance Liquid Chromatography

“…1A, supplemental Table S1). Muropeptide identities can be determined either by collecting the eluted volume from an individual peak and subjecting it to mass spectrometry (MS) (23), or by comparison to previous studies based on the elution time of the peak. Muropeptides fall into general groups of monomers, dimers, and trimers (tetramers are less common) that can be further classified based on the attached peptide stem(s) and/or the presence of an anhydro group on the disaccharide (1,24).…”