Sample preparation methods for MALDI‐MS profiling of bacteria

Šedo, Ondřej; Sedláček, Ivo; Zdráhal, Zbyněk

doi:10.1002/mas.20287

Cited by 94 publications

(55 citation statements)

References 134 publications

(231 reference statements)

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“…The optimal bacterial densities for MALDI-TOF MS have previously been reported as 4 mg cells per 30 mL 51 or 10 6 and 10 7 cells per mL. 48,52 In the present study, we found the optimal bacterial density as ca. 10 7 cells per mL, indicating that, to some extent, the cell density is flexible for MALDI lipid profiling.…”

Section: Effects Of Experimental Conditions On Lipid Profilingsupporting

confidence: 65%

Lipid fingerprinting of Bacillus spp. using online MALDI-TOF mass spectrometry

et al. 2012

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Rapid identification of Bacillus spores has attracted great interest in the medical and forensic communities due to the highly pathogenic nature of certain Bacillus species and its potential application in bioweapons. In this study, we evaluated the feasibility of rapid and reliable identification of several Bacillus spp. (B. subtilis, B. cereus, B. megaterium, B. pumilus, and B. sphaericus) using online MALDI-TOF mass spectrometry combined with lipid profiling. The bacterial cultures in liquid medium were extracted with methanol and chloroform, and the extracts were aerosolized into droplets and immediately analyzed with an online MALDI-TOF mass spectrometer. Results showed that phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and diglycosyldiacylglycerol (DGDG) were present in the mass spectra, as alkali metal adducts. The unique lipid profiles obtained from these Bacillus spp. allowed us to differentiate between them. The reliability and reproducibility of the rapid identification method for Bacillus were tested under different experimental conditions. An alternative online chemotaxonomic method for bacterial identification is demonstrated.

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Section: Effects Of Experimental Conditions On Lipid Profilingsupporting

confidence: 65%

Lipid fingerprinting of Bacillus spp. using online MALDI-TOF mass spectrometry

et al. 2012

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“…MALDI-TOF MS promises to be a fast, reliable, and cost-effective alternative to currently used methods (4,6,8). Apart from the species coverage of the reference database and the identification algorithm of the software (9,10), the sample preparation procedure seems to be critical for the performance of the system (11)(12)(13). Most studies evaluating the Bruker MALDI-TOF MS system used a direct transfer protocol, measuring whole bacterial cells prepared directly from freshly grown colonies.…”

mentioning

confidence: 99%

Identification of Gram-Positive Cocci by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry: Comparison of Different Preparation Methods and Implementation of a Practical Algorithm for Routine Diagnostics

et al. 2013

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This study compared three sample preparation methods (direct transfer, the direct transfer-formic acid method with on-target formic acid treatment, and ethanol-formic acid extraction) for the identification of Gram-positive cocci with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). A total of 156 Gram-positive cocci representing the clinically most important genera, Aerococcus, Enterococcus, Staphylococcus, and Streptococcus, as well as more rare genera, such as Gemella and Granulicatella, were analyzed using a Bruker MALDI Biotyper. The rate of correct genus-level identifications was approximately 99% for all three sample preparation methods. The species identification rate was significantly higher for the direct transfer-formic acid method and ethanol-formic acid extraction (both 77.6%) than for direct transfer (64.1%). Using direct transfer-formic acid compared to direct transfer, the total time to result was increased by 22.6%, 16.4%, and 8.5% analyzing 12, 48, and 96 samples per run, respectively. In a subsequent prospective study, 1,619 clinical isolates of Gram-positive cocci were analyzed under routine conditions by MALDI-TOF MS, using the direct transfer-formic acid preparation, and by conventional biochemical methods. For 95.6% of the isolates, a congruence between conventional and MALDI-TOF MS identification was observed. Two major limitations were found using MALDI-TOF MS: the differentiation of members of the Streptococcus mitis group and the identification of Streptococcus dysgalactiae. The Bruker MALDI Biotyper system using the direct transfer-formic acid sample preparation method was shown to be a highly reliable tool for the identification of Gram-positive cocci. We here suggest a practical algorithm for the clinical laboratory combining MALDI-TOF MS with phenotypic and molecular methods.

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“…With this respect, several technological approaches have been proposed, such as accurate protocols standardization, bio-inspired bacteria purification systems, coupling with separative techniques, high-resolution MS methods, and bioinformatic tools [92][93][94][95]. Employing the pathogenic bacteria E. coli O157:H7 and Yersinia enterocolitica and the non-pathogenic E. coli MC1061 strain as model samples, we recently proposed the use of chemometric tools to extract relevant information, useful for comparing the fingerprint MALDI-TOF spectra of unknown bacteria with a spectral library, to accomplish robust bacteria identification and classification [96].…”

Section: Mass Spectrometrymentioning

confidence: 99%

Recent developments in rapid multiplexed bioanalytical methods for foodborne pathogenic bacteria detection

et al. 2012

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Foodborne illnesses caused by pathogenic bacteria represent a widespread and growing problem to public health, and there is an obvious need for rapid detection of food pathogens. Traditional culture-based techniques require tedious sample workup and are time-consuming. It is expected that new and more rapid methods can replace current techniques. To enable large scale screening procedures, new multiplex analytical formats are being developed, and these allow the detection and/or identification of more than one pathogen in a single analytical run, thus cutting assay times and costs. We review here recent advancements in the field of rapid multiplex analytical methods for foodborne pathogenic bacteria. A variety of strategies, such as multiplex polymerase chain reaction assays, microarray-or multichannel-based immunoassays, biosensors, and fingerprint-based approaches (such as mass spectrometry, electronic nose, or vibrational spectroscopic analysis of whole bacterial cells), have been explored. In addition, various technological solutions have been adopted to improve detectability and to eliminate interferences, although in most cases a brief pre-enrichment step is still required. This review also covers the progress, limitations and future challenges of these approaches and emphasizes the advantages of new separative techniques to selectively fractionate bacteria, thus increasing multiplexing capabilities and simplifying sample preparation procedures.

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Sample preparation methods for MALDI‐MS profiling of bacteria

Cited by 94 publications

References 134 publications

Lipid fingerprinting of Bacillus spp. using online MALDI-TOF mass spectrometry

Lipid fingerprinting of Bacillus spp. using online MALDI-TOF mass spectrometry

Identification of Gram-Positive Cocci by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry: Comparison of Different Preparation Methods and Implementation of a Practical Algorithm for Routine Diagnostics

Recent developments in rapid multiplexed bioanalytical methods for foodborne pathogenic bacteria detection

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