scholarly journals Evaluation of MALDI-ToF Mass Spectrometry for Rapid Detection of Cereulide from Bacillus cereus Cultures

2019 ◽  
Author(s):  
Joerg Doellinger ◽  
Andy Schneider ◽  
Timo Stark ◽  
Monika Ehling-Schulz ◽  
Peter Lasch
Keyword(s):  
Mass Spectrometry ◽  
Bacillus Cereus ◽  
Food Poisoning ◽  
Acid Extraction ◽  
Analytical Sensitivity ◽  
Bacterial Colony ◽  
Routine Diagnostics ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tof Ms

1.AbstractBacillus cereus plays an often unrecognized role in food borne diseases. Food poisoning caused by this pathogen is manifested by either diarrhea or emesis. While different enterotoxins have been linked to the diarrheal type of B. cereus infections, the emetic toxin cereulide is responsible for the second type. Due to the relatively high prevalence of cereulide associated food poisoning, methods for simple and reliable detection of cereulide producing strains are of utmost importance. Currently, liquid-chromatography coupled to mass spectrometry (LC-MS) is used for sensitive, specific and quantitative cereulide detection, but this technique requires specialized LC-MS equipment, which is often not available in microbiology routine diagnostic laboratories.The last decade has witnessed the advent of matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-ToF MS) as a simple, rapid and cost-efficient technique for identification of microbial pathogens in routine diagnostics. Just recently, two different studies reported on the application of MALDI-ToF MS for either the differentiation of emetic and non-emetic strains of B. cereus or for direct detection of cereulide from bacterial colony smears. However, no method evaluation and optimization was performed in frame of these studies. Thus, additional investigations on the selectivity and sensitivity of MALDI-TOF MS for cereulide detection are needed before implementation of this method in routine diagnostics can be considered. These aspects prompted us to investigate open or controversial issues and to systematically test sample preparation methods, commonly used for microbial identification for their suitability to detect the emetic toxin directly from bacteria.Based on our experimental findings we propose a MALDI-ToF MS workflow that allows identification of B. cereus and sensitive detection of cereulide in parallel, using standard, linear-mode MALDI-ToF MS equipment. The experimental protocol is based on the well-established ethanol/formic acid extraction method and offers, if required, possibilities for further characterization by more sophisticated LC-MS-based methods. In summary, the ease of use and the achieved level of analytical sensitivity as well as the wide-spread availability of standard MALDI-ToF MS equipment in clinical microbiological laboratories provides a promising tool to improve and to facilitate routine diagnostics of B. cereus associated food intoxications.

scholarly journals Discrimination of Bacillus cereus Group Members by MALDI-TOF Mass Spectrometry

2021 ◽  
Vol 9 (6) ◽  
pp. 1202
Author(s):  
Viviana Manzulli ◽  
Valeria Rondinone ◽  
Alessandro Buchicchio ◽  
Luigina Serrecchia ◽  
Dora Cipolletta ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Bacillus Cereus ◽  
Mass Spectra ◽  
Critical Time ◽  
Principal Component ◽  
Etiologic Agent ◽  
Bacillus Cereus Group ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tof Ms

Matrix-Assisted Laser Desorption/Ionization Time Of Flight Mass Spectrometry (MALDI-TOF MS) technology is currently increasingly used in diagnostic laboratories as a cost effective, rapid and reliable routine technique for the identification and typing of microorganisms. In this study, we used MALDI-TOF MS to analyze a collection of 160 strains belonging to the Bacillus cereus group (57 B. anthracis, 49 B. cereus, 1 B. mycoides, 18 B. wiedmannii, 27 B. thuringiensis, 7 B. toyonensis and 1 B. weihenstephanensis) and to detect specific biomarkers which would allow an unequivocal identification. The Main Spectra Profiles (MSPs) were added to an in-house reference library, expanding the current commercial library which does not include B. toyonensis and B. wiedmannii mass spectra. The obtained mass spectra were statistically compared by Principal Component Analysis (PCA) that revealed seven different clusters. Moreover, for the identification purpose, were generated dedicate algorithms for a rapid and automatic detection of characteristic ion peaks after the mass spectra acquisition. The presence of specific biomarkers can be used to differentiate strains within the B. cereus group and to make a reliable identification of Bacillus anthracis, etiologic agent of anthrax, which is the most pathogenic and feared bacterium of the group. This could offer a critical time advantage for the diagnosis and for the clinical management of human anthrax even in case of bioterror attacks.

scholarly journals Evaluation of MALDI–TOF Mass Spectrometry in Diagnostic and Environmental Surveillance of Legionella Species: A Comparison With Culture and Mip-Gene Sequencing Technique

2020 ◽  
Vol 11 ◽  
Author(s):  
Maria Rosaria Pascale ◽  
Marta Mazzotta ◽  
Silvano Salaris ◽  
Luna Girolamini ◽  
Antonella Grottola ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Phylogenetic Analysis ◽  
Legionella Pneumophila ◽  
Gene Sequencing ◽  
Species Level ◽  
Environmental Surveillance ◽  
Routine Diagnostics ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tof Ms

Legionella spp. are widespread bacteria in aquatic environments with a growing impact on human health. Between the 61 species, Legionella pneumophila is the most prevalent in human diseases; on the contrary, Legionella non-pneumophila species are less detected in clinical diagnosis or during environmental surveillance due to their slow growth in culture and the absence of specific and rapid diagnostic/analytical tools. Reliable and rapid isolate identification is essential to estimate the source of infection, to undertake containment measures, and to determine clinical treatment. Matrix-assisted laser desorption ionization–time-of-flight mass spectrometry (MALDI–TOF MS), since its introduction into the routine diagnostics of laboratories, represents a widely accepted method for the identification of different bacteria species, described in a few studies on the Legionella clinical and environmental surveillance. The focus of this study was the improvement of MALDI–TOF MS on Legionella non-pneumophila species collected during Legionella nosocomial and community surveillance. Comparative analysis with cultural and mip-gene sequencing results was performed. Moreover, a phylogenetic analysis was carried out to estimate the correlations amongst isolates. MALDI–TOF MS achieved correct species-level identification for 45.0% of the isolates belonging to the Legionella anisa, Legionella rubrilucens, Legionella feeleii, and Legionella jordanis species, displaying a high concordance with the mip-gene sequencing results. In contrast, less reliable identification was found for the remaining 55.0% of the isolates, corresponding to the samples belonging to species not yet included in the database. The phylogenetic analysis showed relevant differences inside the species, regruped in three main clades; among the Legionella anisa clade, a subclade with a divergence of 3.3% from the main clade was observed. Moreover, one isolate, identified as Legionella quinlivanii, displayed a divergence of 3.8% from the corresponding reference strain. However, these findings require supplementary investigation. The results encourage the implementation of MALDI–TOF MS in routine diagnostics and environmental Legionella surveillance, as it displays a reliable and faster identification at the species level, as well as the potential to identify species that are not yet included in the database. Moreover, phylogenetic analysis is a relevant approach to correlate the isolates and to track their spread, especially in unconventional reservoirs, where Legionella prevention is still underestimated.

scholarly journals Using MALDI-ToF mass spectrometry to identify mushroom species: Proof of concept analysis of Amanita genus specimens

2021 ◽  
Author(s):  
Raphael Piarroux ◽  
Frédéric Gabriel ◽  
Frédéric Grenouillet ◽  
Patrick Collombon ◽  
Philippe Louasse ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Food Poisoning ◽  
Laser Desorption ◽  
Reference Database ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Maldi Tof Ms ◽  
The Past ◽  
Maldi Tof ◽  
Tof Ms

Abstract Food poisoning caused by toxic mushrooms, such as species in the Amanita genus, occurs frequently around the world. To properly treat these patients, it is important to rapidly and accurately identify the causal species. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry is a rapid technique that has been used in medical laboratories for the past three decades to identify bacteria, yeasts, and filamentous fungi. Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-Tof MS) is a rapid method used for the past three decades to identify microorganisms. In this study, we created and internally validated a MALDI-Tof MS reference database comprising 15 Amanita species frequently encountered in France, and we challenged this database with 38 Amanita specimens from four French locations, using a free online application for MALDI-ToF spectra identifications. Assessment of the database showed that mass spectra can be obtained by analyzing any portion of a carpophore and that all portions enabled identification of the carpophore at the species level. Most carpophores were correctly identified using our database, with the exception of specimens from the Vaginatae section. Decay tests also demonstrated that decayed portions (like those found in the kitchen garbage can) of Amanita phalloides mushrooms could be properly identified using MALDI-ToF MS. Our findings provide important insight for toxicology laboratories that often rely on DNA sequencing to identify meal leftovers implicated in food poisoning. In future developments, this technique could also be used to detect counterfeit mushrooms by including other genera in the reference database. Lay Summary MALDI-ToF MS is a powerful identification tool for microorganisms. We demonstrate that the technique can be applied to Amanita specimens. This will prevent food intoxications as a rapid and definite identification can be obtained, and it can also be used for food remnants.

scholarly journals Performance of MALDI-TOF Mass Spectrometry for the Identification of the HACEK Group and Other Fastidious Gram-Negative Rods

2019 ◽  
Vol 13 (1) ◽  
pp. 216-221 ◽  
Author(s):  
Marisa Almuzara ◽  
Karen C. V. Cárdenas ◽  
Claudia Barberis ◽  
Maria S. Ramirez ◽  
Angela Famiglietti ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Formic Acid ◽  
Extraction Methods ◽  
Species Level ◽  
Acid Extraction ◽  
Gram Negative ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Routine Identification ◽  
Tof Ms

Objective: The aim of this study was to determine the capacity of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) to identify 155 HACEK clinical isolates and other fastidious or infrequently isolated Gram-negative rods (e.g., Actinobacillus, Capnocytophaga, Pasteurella, Neisseria, Moraxella, Dysgonomonas, among others). Methods: All the isolates were identified by standard biochemical tests and MALDI-TOF MS. Two different extraction methods (direct transfer formic acid method on spot and ethanol formic acid extraction method) and different cut-offs for genus/specie level identification were used. MALDI-TOF MS identification was considered correct when the result obtained from the MS database agreed with the phenotypic identification result. When both the methods gave discordant results, the 16S rDNA gene sequencing was considered as the gold standard identification method. Results: Employing the score cut-offs suggested by the manufacturer, 93.55% and 69.03% isolates were correctly identified at the genus and species level, respectively. On the contrary , employing lower cut-off scores for identification, 98.06% and 92.09% isolates were properly identified at the genus and species level respectively and no significant differences between the results obtained with two extraction methods were observed . Conclusion: The accurate identification of 14 genera showed the reliability of MALDI-TOF MS as an optional methodology to the routine identification methods currently used in laboratories.

scholarly journals Diagnostic accuracy of MALDI-TOF mass spectrometry for the direct identification of clinical pathogens from urine

Open Medicine ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 266-273
Author(s):  
Min Tang ◽  
Jia Yang ◽  
Ying Li ◽  
Luhua Zhang ◽  
Ying Peng ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Likelihood Ratio ◽  
Meta Analysis ◽  
Positive Likelihood Ratio ◽  
Negative Likelihood Ratio ◽  
Urine Samples ◽  
Direct Identification ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tof Ms

AbstractMatrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) has become one of the most popular methods for the rapid and cost-effective detection of clinical pathogenic microorganisms. This study aimed to evaluate and compare the diagnostic performance of MALDI-TOF MS with that of conventional approaches for the direct identification of pathogens from urine samples. A systematic review was conducted based on a literature search of relevant databases. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and area under the summary receiver operating characteristic (SROC) curve of the combined studies were estimated. Nine studies with a total of 3920 subjects were considered eligible and included in the meta-analysis. The pooled sensitivity was 0.85 (95% CI 0.79-0.90), and the pooled specificity was 0.93 (95% CI 0.82-0.97). The PLR and NLR were 11.51 (95% CI 4.53-29.26) and 0.16 (95% CI 0.11-0.24), respectively. The area under the SROC curve was 0.93 (95% CI 0.91-0.95). Sensitivity analysis showed that the results of this meta-analysis were stable. MALDI-TOF MS could directly identify microorganisms from urine samples with high sensitivity and specificity.

scholarly journals The Use of MALDI-TOF Mass Spectrometry to Analyze Commensal Oral Yeasts in Nursing Home Residents

2021 ◽  
Vol 9 (1) ◽  
pp. 142
Author(s):  
Jang-Jih Lu ◽  
Hsiu-Jung Lo ◽  
Chih-Hua Lee ◽  
Mei-Jun Chen ◽  
Chih-Chao Lin ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Nursing Home ◽  
Dna Sequences ◽  
Nursing Home Residents ◽  
Practical Method ◽  
Elderly Subjects ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Oral Yeasts ◽  
Tof Ms

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a rapid and accurate method to identify microorganisms in clinical laboratories. This study isolates yeast-like microorganisms in the oral washes that are collected from non-bedridden nursing home residents, using CHROMagar Candida plates, and identifies them using Bruker MALDI-TOF MS. The ribosomal DNA sequences of the isolates are then examined. Three hundred and twenty yeast isolates are isolated from the oral washes. Candida species form the majority (78.1%), followed by Trichosporon/Cutaneotrichosporon species (8.8%). Bruker MALDI-TOF MS gives a high-level confidence, with a log(score) value of ≥1.8, and identifies 96.9% of the isolates. There are six inconclusive results (1.9%), and those sequences are verified as rare clinical species, including Candida ethanolica, Cutaneotrichosporon jirovecii, Exophiala dermatitidis, and Fereydounia khargensis. Almost all of the isolates have a regular color on the CHROMagar Candida plates. If the colonies are grouped by color on the plates, a specific dominant yeast species is present in each color group, except for purple or orange isolates. In conclusion, MALDI-TOF MS is verified as a fast, accurate and practical method to analyze oral yeasts in elderly subjects.

Microorganism idenitfication – stability and correctness of mass spectrometry method (MALDI TOF MS)

2021 ◽  
Vol 56 (4) ◽  
pp. 1-12
Author(s):  
Łukasz Hildebrant ◽  
Urszula Wendt
Keyword(s):  
Mass Spectrometry ◽  
Quality Control ◽  
Control System ◽  
High Stability ◽  
Spectrometry Method ◽  
Maldi Tof Ms ◽  
Mass Spectrometry Method ◽  
Maldi Tof ◽  
Reference Strains ◽  
Tof Ms

Introduction: MALDI TOF MS method is increasingly used in routine microbiological diagnostics to identify clinical strains. The result of the identification test is based on the measurement of the mass, charge and flight time of the protein ions. This makes it possible to monitor and supervise the method using a numerical score developed with statistical techniques. Aim: The study aimed to determine the stability and correctness of the mass spectrometry method. Materials and methods: To evaluate the characteristics of the method, microbial identification tests were performed using reference strains. All tests were performed as part of the MALDI TOF MS internal quality control system. Results: All reference strains (100%) were correctly identified to the species level, although the score values were not always within the reliability criteria of the results established by the producer. It was found that the mean values of the score were from 2.000 – 2.299 (49.2%) and 2.300 – 3.000 (50.0%). The coefficient of variation for control tests performed in the consecutive years ranged from 5.18 – 6.56%, which evidence of the high stability of the method. For individual species, reproducibility precision over the 8 years ranged from 2.89% (n = 13) for Enterococcus faecalis ATCC 51299 to 7.02% (n = 28) for Klebsiella pneumoniae ATCC 700603, which proves the high precision of measurements. Conclusions: The mass spectrometry method is characterized by very high stability and correctness. The intra-laboratory quality control system using reference strains is a useful tool for monitoring and supervising the method and laboratory personnel competency performing identification tests during routine microbiological work.

scholarly journals Detection of Structural and Conformational Changes in ALS-Causing Mutant Profilin1 With Hydrogen/Deuterium Exchange Mass Spectrometry and Bioinformatics Techniques

2021 ◽  
Author(s):  
Ahmad Shahir Sadr ◽  
zahra abdollahpour ◽  
Atousa Aliahmadi ◽  
Changiz Eslahchi ◽  
Mina Nekouei ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Amino Acids ◽  
Amino Acid ◽  
Conformational Changes ◽  
Docking Simulation ◽  
Hydrogen Deuterium Exchange ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Hydrogen Deuterium ◽  
Tof Ms

Abstract The hydrogen/deuterium exchange (HDX) is a reliable method to survey the dynamic behavior of proteins and epitope mapping. Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) is a quantifying tool to assay for HDX in the protein of interest. We combined HDX-MALDI-TOF MS and molecular docking/MD simulation to identify accessible amino acids and analyze their contribution in the structural changes of profilin1 (PFN1). The molecular docking/MD simulations are computational tools for enabling the analysis of the type of amino acids that may be involved via HDX identified under the lowest binding energy condition. Glycine to Valine amino acid (G117V) substitution mutation is linked to amyotrophic lateral sclerosis (ALS). This mutation is found to be in the actin-binding site of PFN1 and prevents the dimerization/polymerization of actin and invokes a pathologic toxicity that leads to ALS. In this study, we sought to understand the PFN1 protein dynamic behavior using purified wild type and mutant PFN1 proteins. The data obtained from HDX-MALDI-TOF MS for PFN1WT and PFN1G117V at various time intervals, from seconds to hours, revealed multiple peaks corresponding to molecular weights from monomers to multimers. PFN1/Benzaldehyde complexes identified 20 accessible amino acids to HDX that participate in the docking simulation in the surface of WT and mutant PFN1. Consistent results from HDX-MALDI-TOF MS and docking simulation predict candidate amino acid(s) involved in the dimerization/polymerization of PFNG117V. This information may shed critical light on the structural and conformational changes with details of amino acid epitopes for mutant PFN1s’ dimerization, oligomerization, and aggregation.

scholarly journals Outbreak of botulism type A in dairy cows detected by MALDI-TOF mass spectrometry

2020 ◽  
Vol 32 (5) ◽  
pp. 722-726
Author(s):  
Elisha A. Frye ◽  
Christina Egan ◽  
Michael J. Perry ◽  
Esther E. Crouch ◽  
Kyle E. Burbank ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
New York ◽  
New York State ◽  
Clinical Signs ◽  
Type A ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Botulinum Type ◽  
Type C ◽  
Tof Ms

Twenty-eight lactating dairy cattle in New York State were exposed to botulism toxin; 12 died and 16 recovered but never returned to full productivity. Pieces of a raccoon carcass were found in the total mixed ration on the first day of the outbreak. Clinical signs included anorexia, decreased milk production, decreased tongue tone, profound weakness, and recumbency. Clostridium botulinum type A (BoNT/A) was detected in rumen contents from 2 deceased cows via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). In addition, C. botulinum type C was cultured from the liver of a third cow, and C. botulinum neurotoxin-producing type C gene ( bont/C) was detected via real-time PCR. On postmortem examination, 4 cows had findings suggestive of toxic myopathy, but the cause and significance of these lesions is unknown given that botulism is typically not associated with gross or histologic lesions. This outbreak of BoNT/A in cattle in North America was diagnosed via MALDI-TOF MS, a rapid and sensitive modality for detection of botulinum preformed neurotoxin.

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