scholarly journals Rapid Screening of Epidemiologically Important Salmonella enterica subsp. enterica Serovars by Whole-Cell Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

2011 ◽  
Vol 77 (12) ◽  
pp. 4136-4146 ◽  
Author(s):  
Ralf Dieckmann ◽  
Burkhard Malorny
Keyword(s):  
Mass Spectrometry ◽  
Salmonella Enterica ◽  
Laser Desorption ◽  
Rapid Screening ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Content Type ◽  
Maldi Tof Mass Spectrometry ◽  
Maldi Tof ◽  
Matrix Assisted Laser

ABSTRACTCurrently, 2,610 differentSalmonellaserovars have been described according to the White-Kauffmann-Le Minor scheme. They are routinely differentiated by serotyping, which is based on the antigenic variability at lipopolysaccharide moieties (O antigens), flagellar proteins (H1 and H2 antigens), and capsular polysaccharides (Vi antigens). The aim of this study was to evaluate the potential of matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry for rapid screening and identification of epidemiologically importantSalmonella entericasubsp.entericaserovars based on specific sets of serovar-identifying biomarker ions. By analyzing 913Salmonella entericasubsp.entericastrains representing 89 different serovars using MALDI-TOF mass spectrometry, several potentially serovar-identifying biomarker ions were selected. Based on a combination of genus-, species-, subspecies-, and serovar-identifying biomarker ions, a decision tree classification algorithm was derived for the rapid identification of the five most frequently isolatedSalmonella entericaserovars, Enteritidis, Typhimurium/4,[5],12:i:-, Virchow, Infantis, and Hadar. Additionally, sets of potentially serovar-identifying biomarker ions were detected for other epidemiologically interesting serovars, such as Choleraesuis, Heidelberg, and Gallinarum. Furthermore, by using a bioinformatic approach, sequence variations corresponding to single or multiple amino acid exchanges in several biomarker proteins were tentatively assigned. The inclusivity and exclusivity of the specific sets of serovar-identifying biomarker ions for the top 5 serovars were almost 100%. This study shows that whole-cell MALDI-TOF mass spectrometry can be a rapid method for prescreeningS. entericasubsp.entericaisolates to identify epidemiologically important serovars and to reduce sample numbers that have to be subsequently analyzed using conventional serotyping by slide agglutination techniques.

scholarly journals Performance of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identifying Clinical Malassezia Isolates

2016 ◽  
Vol 55 (1) ◽  
pp. 90-96 ◽  
Author(s):  
Julie Denis ◽  
Marie Machouart ◽  
Florent Morio ◽  
Marcela Sabou ◽  
Catherine Kauffmann-LaCroix ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Content Type ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

ABSTRACT The genus Malassezia comprises commensal yeasts on human skin. These yeasts are involved in superficial infections but are also isolated in deeper infections, such as fungemia, particularly in certain at-risk patients, such as neonates or patients with parenteral nutrition catheters. Very little is known about Malassezia epidemiology and virulence. This is due mainly to the difficulty of distinguishing species. Currently, species identification is based on morphological and biochemical characteristics. Only molecular biology techniques identify species with certainty, but they are time-consuming and expensive. The aim of this study was to develop and evaluate a matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) database for identifying Malassezia species by mass spectrometry. Eighty-five Malassezia isolates from patients in three French university hospitals were investigated. Each strain was identified by internal transcribed spacer sequencing. Forty-five strains of the six species Malassezia furfur , M. sympodialis , M. slooffiae , M. globosa , M. restricta , and M. pachydermatis allowed the creation of a MALDI-TOF database. Forty other strains were used to test this database. All strains were identified by our Malassezia database with log scores of >2.0, according to the manufacturer's criteria. Repeatability and reproducibility tests showed a coefficient of variation of the log score values of <10%. In conclusion, our new Malassezia database allows easy, fast, and reliable identification of Malassezia species. Implementation of this database will contribute to a better, more rapid identification of Malassezia species and will be helpful in gaining a better understanding of their epidemiology.

scholarly journals Rapid and Robust Identification of the Agents of Black-Grain Mycetoma by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

2017 ◽  
Vol 55 (8) ◽  
pp. 2521-2528 ◽  
Author(s):  
Mark Fraser ◽  
Andrew M. Borman ◽  
Elizabeth M. Johnson
Keyword(s):  
Mass Spectrometry ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Accurate Identification ◽  
Ionization Time ◽  
Content Type ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

ABSTRACTEumycetoma, a chronic fungal infection endemic in India, Indonesia, and parts of Africa and South and Central America, follows traumatic implantation of saprophytic fungi and frequently requires radical surgery or amputation in the absence of appropriate treatment. Fungal species that can cause black-grain mycetomas includeMadurellaspp.,Falciformisporaspp.,Trematosphaeria grisea,Nigrograna mackinnonii,Pseudochaetosphaeronema larense,Medicopsis romeroi, andEmarelliaspp.Rhytidhysteron rufulumandParathyridaria percutaneacause similar subcutaneous infections, but these infections lack the draining sinuses and fungal grains characteristic of eumycetoma. Accurate identification of the agents of subcutaneous fungal infection is essential to guide appropriate antifungal therapy. Since phenotypic identification of the causative fungi is often difficult, time-consuming molecular approaches are currently required. In the study described here we evaluated whether matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry might allow the accurate identification of eumycetoma agents and related fungi. A panel of 57 organisms corresponding to 10 different species from confirmed cases of eumycetoma and subcutaneous pedal masses, previously formally identified by PCR amplification and sequencing of internal transcribed spacer 1 (ITS1), was employed. Representative isolates of each species were used to create reference MALDI-TOF spectra, which were then used for the identification of the remaining isolates in a user-blinded manner. Here, we demonstrate that MALDI-TOF mass spectrometry accurately identified all of the test isolates, with 100%, 90.4%, and 67.3% of isolates achieving log scores greater than 1.8, 1.9, and 2.0, respectively.

scholarly journals Peaks of Promise and Peril: Screening for Antibiotic Resistance by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

2015 ◽  
Vol 54 (1) ◽  
pp. 5-6 ◽  
Author(s):  
Neil W. Anderson
Keyword(s):  
Mass Spectrometry ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Maldi Tof Mass Spectrometry ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

An article in this issue of theJournal of Clinical Microbiology(J.-H. Youn, S. K. Drake, R. A. Weingarten, K. M. Frank, J. P. Dekker, and A. F. Lau, J Clin Microbiol 53:35–42, 2015,http://dx.doi.org/10.1128/JCM.01643-15) describes the use of matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry for the detection of organisms carrying ablaKPC-containing plasmid. This powerful and promising application highlights the challenges of using MALDI-TOF mass spectrometry for purposes other than organism identification.

scholarly journals Efficient Detection of Carbapenemase Activity in Enterobacteriaceae by Matrix-Assisted Laser Desorption Ionization−Time of Flight Mass Spectrometry in Less Than 30 Minutes

2015 ◽  
Vol 53 (7) ◽  
pp. 2163-2171 ◽  
Author(s):  
Camille Lasserre ◽  
Luc De Saint Martin ◽  
Gaelle Cuzon ◽  
Pierre Bogaerts ◽  
Estelle Lamar ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Content Type ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

The recognition of carbapenemase-producingEnterobacteriaceae(CPE) isolates is a major laboratory challenge, and their inappropriate or delayed detection may have negative impacts on patient management and on the implementation of infection control measures. We describe here a matrix-assisted laser desorption ionization−time of flight (MALDI-TOF)-based method to detect carbapenemase activity inEnterobacteriaceae. After a 20-min incubation of the isolate with 0.5 mg/ml imipenem at 37°C, supernatants were analyzed by MALDI-TOF in order to identify peaks corresponding to imipenem (300 Da) and an imipenem metabolite (254 Da). A total of 223 strains, 77 CPE (OXA-48 variants, KPC, NDM, VIM, IMI, IMP, and NMC-A) and 146 non-CPE (cephalosporinases, extended-spectrum β-lactamases [ESBLs], and porin defects), were tested and used to calculate a ratio of imipenem hydrolysis: mass spectrometry [MS] ratio = metabolite/(imipenem + metabolite). An MS ratio cutoff was statistically determined to classify strains as carbapenemase producers (MS ratio of ≥0.82). We validated this method first by testing 30 of our 223 isolates (15 CPE and 15 non-CPE) 10 times to calculate an intraclass correlation coefficient (ICC of 0.98), showing the excellent repeatability of the method. Second, 43 strains (25 CPE and 18 non-CPE) different from the 223 strains used to calculate the ratio cutoff were used as external controls and blind tested. They yielded sensitivity and specificity of 100%. The total cost per test is <0.10 U.S. dollars (USD). This easy-to-perform assay is time-saving, cost-efficient, and highly reliable and might be used in any routine laboratory, given the availability of mass spectrometry, to detect CPE.

scholarly journals Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry of Lipopeptide Biosurfactants in Whole Cells and Culture Filtrates of Bacillus subtilis C-1 Isolated from Petroleum Sludge

2002 ◽  
Vol 68 (12) ◽  
pp. 6210-6219 ◽  
Author(s):  
Joachim Vater ◽  
Bärbel Kablitz ◽  
Christopher Wilde ◽  
Peter Franke ◽  
Neena Mehta ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Maldi Tof Mass Spectrometry ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Lipopeptide Biosurfactants ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

ABSTRACT An innovative method was developed for rapid sensitive detection and efficient structural characterization of lipopeptide biosurfactants by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry by using whole microbial cells and crude culture filtrates as targets in combination with surface tension measurements. This was done for a bacterial strain that was isolated from petroleum sludge and efficiently produces biosurfactants. This organism was identified by using biochemical, physiological, and genetic parameters as a Bacillus subtilis strain, designated B. subtilis C-1. This assignment was supported by a mass spectrometric investigation of the secondary metabolite spectrum determined by whole-cell MALDI-TOF mass spectrometry, which revealed three lipopeptide complexes, the surfactins, the iturins, and the fengycins, which are well-known biosurfactants produced by B. subtilis strains. These compounds were structurally characterized by in situ structure analysis by using postsource decay MALDI-TOF mass spectrometry. The isoforms were separated by miniaturized high-resolution reversed-phase high-performance liquid chromatography for mass spectrometric characterization. Iturin compounds which contain unusual fatty acid components were detected.

scholarly journals Four Common Mutations of the Cystathionine β-Synthase Gene Detected by Multiplex PCR and Matrix-assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

1999 ◽  
Vol 45 (8) ◽  
pp. 1157-1161 ◽  
Author(s):  
Angela Harksen ◽  
Per Magne Ueland ◽  
Helga Refsum ◽  
Klaus Meyer
Keyword(s):  
Mass Spectrometry ◽  
Multiplex Pcr ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Maldi Tof Mass Spectrometry ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

Abstract Background: A deficiency of cystathionine β-synthase (CBS) is the most frequent cause of homocystinuria. The effect of therapy is related to the underlying CBS genotype, which makes early diagnosis of this genetic defect important. Our aim was to develop a fast and reliable method based on matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry for the determination of common mutations of the CBS gene. Methods: We used MALDI-TOF mass spectrometry to detect four common CBS mutations (G307S, T272M, I278T, and V320A). The method is based on multiplex PCR of exons 7, 8, and 9, followed by single nucleotide extension in the presence of dideoxy NTPs of four primers targeted at the separate mutation sites. The extension products, as well as the 3-hydroxypicolinic acid matrix, were incubated with cation-exchange beads to remove disturbing salt contaminants. Results: The above-mentioned mutations were determined in samples from 12 homocystinuria patients. The MALDI-TOF spectra allowed unambiguous discrimination between primers and extension products (&gt;9 Da) in the mass range between 4500 and 7500 Da. No labeled primers or ddNTPs were required. The genotyping was verified by reference technique. Conclusion: Our results demonstrate fast, simple, and unambiguous multiplex genotyping of four common CBS mutations by MALDI-TOF mass spectrometry.

scholarly journals Creation of an In-House Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Corynebacterineae Database Overcomes Difficulties in Identification of Nocardia farcinica Clinical Isolates

2015 ◽  
Vol 53 (8) ◽  
pp. 2611-2621 ◽  
Author(s):  
Mariola Paściak ◽  
Władysław Dacko ◽  
Joanna Sikora ◽  
Danuta Gurlaga ◽  
Krzysztof Pawlik ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Content Type ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

Nocardiosis is a rare disease that is caused by Gram-positive actinobacteria of theNocardiagenus and affects predominantly immunocompromised patients. In its disseminated form, it has a predilection for the central nervous system and is associated with high mortality rates. Therefore, prompt identification of the pathogen is critical. Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry is a relatively novel technique used for identification of microorganisms. In this work, an upgraded MALDI-TOF Biotyper database containingCorynebacterineaerepresentatives of strains deposited in the Polish Collection of Microorganisms was created and used for identification of the strain isolated from a nocardial brain abscess, mimicking a brain tumor, in an immunocompetent patient. Testing with the API Coryne system initially incorrectly identifiedRhodococcussp., while chemotaxonomic tests, especially mycolic acid analysis, enabled correctNocardiaidentification only at the genus level. Subsequent sequence analysis of 16S rRNA andsecA1genes confirmed the identification. To improve the accuracy of the results, an in-house database was constructed using optimized parameters; with the use of the database, the strain was eventually identified asNocardia farcinica. Clinical laboratories processing various clinical strains can upgrade a commercial database to improve and to accelerate the results obtained. This is especially important in the case ofNocardia, for which valid microbial diagnosis remains challenging; reference laboratories are often required to identify and to survey these rare actinobacteria.

scholarly journals Evaluation of a Semiquantitative Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Method for Rapid Antimicrobial Susceptibility Testing of Positive Blood Cultures

2016 ◽  
Vol 54 (11) ◽  
pp. 2820-2824 ◽  
Author(s):  
Jette S. Jung ◽  
Christina Hamacher ◽  
Birgit Gross ◽  
Katrin Sparbier ◽  
Christoph Lange ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Laser Desorption ◽  
Blood Cultures ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Maldi Tof Mass Spectrometry ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

With the increasing prevalence of multidrug-resistant Gram-negative bacteria, rapid identification of the pathogen and its individual antibiotic resistance is crucial to ensure adequate antiinfective treatment at the earliest time point. Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry for the identification of bacteria directly from the blood culture bottle has been widely established; however, there is still an urgent need for new methods that permit rapid resistance testing. Recently, a semiquantitative MALDI-TOF mass spectrometry-based method for the prediction of antibiotic resistance was described. We evaluated this method for detecting nonsusceptibility against two β-lactam and two non-β-lactam antibiotics. A collection of 30 spiked blood cultures was tested for nonsusceptibility against gentamicin and ciprofloxacin. Furthermore, 99 patient-derived blood cultures were tested for nonsusceptibility against cefotaxime, piperacillin-tazobactam, and ciprofloxacin in parallel with MALDI-TOF mass spectrometry identification from the blood culture fluid. The assay correctly classified all isolates tested for nonsusceptibility against gentamicin and cefotaxime. One misclassification for ciprofloxacin nonsusceptibility and five misclassifications for piperacillin-tazobactam nonsusceptibility occurred. Identification of the bacterium and prediction of nonsusceptibility was possible within approximately 4 h.

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