Journal articles: 'MALDI-TOF MS'

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NIRASAWA, TAKASHI. "MALDI-TOF-MS." Kagaku To Seibutsu 34, no. 4 (1996): 255–59. http://dx.doi.org/10.1271/kagakutoseibutsu1962.34.255.

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Rim, John Hoon, Yangsoon Lee, Sung Kuk Hong, Yongjung Park, MyungSook Kim, Roshan D’Souza, Eun Suk Park, Dongeun Yong, and Kyungwon Lee. "Insufficient Discriminatory Power of Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry Dendrograms to Determine the Clonality of Multi-Drug-ResistantAcinetobacter baumanniiIsolates from an Intensive Care Unit." BioMed Research International 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/535027.

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While pulsed-field gel electrophoresis (PFGE) is recognized as the gold standard method for clonality analysis, MALDI-TOF MS has recently been spotlighted as an alternative tool for species identification. Herein, we compared the dendrograms of multi-drug-resistant (MDR)Acinetobacter baumanniiisolates by using MALDI-TOF MS with those by using PFGE. We used direct colony and protein extraction methods for MALDI-TOF MS dendrograms. The isolates with identical PFGE patterns were grouped into different branches in MALDI-TOF MS dendrograms. Among the isolates that were classified as very close isolates in MALDI-TOF MS dendrogram, PFGE band patterns visually showed complete differences. We numeralized similarity among isolates by measuring distance levels. The Spearman rank correlation coefficient values were 0.449 and 0.297 between MALDI-TOF MS dendrogram using direct colony and protein extraction method versus PFGE, respectively. This study is the first paper focusing solely on the dendrogram function of MALDI-TOF MS compared with PFGE. Although MALDI-TOF MS is a promising tool to identify species in a rapid manner, our results showed that MALDI-TOF MS dendrograms could not substitute PFGE for MDRAcinetobacter baumanniiclonality analysis.

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Chen, Xin-Fei, Xin Hou, Meng Xiao, Li Zhang, Jing-Wei Cheng, Meng-Lan Zhou, Jing-Jing Huang, Jing-Jia Zhang, Ying-Chun Xu, and Po-Ren Hsueh. "Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) Analysis for the Identification of Pathogenic Microorganisms: A Review." Microorganisms 9, no. 7 (July 19, 2021): 1536. http://dx.doi.org/10.3390/microorganisms9071536.

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Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used in the field of clinical microbiology since 2010. Compared with the traditional technique of biochemical identification, MALDI-TOF MS has many advantages, including convenience, speed, accuracy, and low cost. The accuracy and speed of identification using MALDI-TOF MS have been increasing with the development of sample preparation, database enrichment, and algorithm optimization. MALDI-TOF MS has shown promising results in identifying cultured colonies and rapidly detecting samples. MALDI-TOF MS has critical research applications for the rapid detection of highly virulent and drug-resistant pathogens. Here we present a scientific review that evaluates the performance of MALDI-TOF MS in identifying clinical pathogenic microorganisms. MALDI-TOF MS is a promising tool in identifying clinical microorganisms, although some aspects still require improvement.

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Sousa, Roberto B., Keila S. C. Lima, Caleb G. M. Santos, Tanos C. C. França, Eugenie Nepovimova, Kamil Kuca, Marcos R. Dornelas, and Antonio L. S. Lima. "A New Method for Extraction and Analysis of Ricin Samples through MALDI-TOF-MS/MS." Toxins 11, no. 4 (April 3, 2019): 201. http://dx.doi.org/10.3390/toxins11040201.

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We report for the first time the efficient use of accelerated solvent extraction (ASE) for extraction of ricin to analytical purposes, followed by the combined use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and MALDI-TOF MS/MS method. That has provided a fast and unambiguous method of ricin identification for in real cases of forensic investigation of suspected samples. Additionally, MALDI-TOF MS was applied to characterize the presence and the toxic activity of ricin in irradiated samples. Samples containing ricin were subjected to ASE, irradiated with different dosages of gamma radiation, and analyzed by MALDI-TOF MS/MS for verification of the intact protein signal. For identification purposes, samples were previously subjected to SDS-PAGE, for purification and separation of the chains, followed by digestion with trypsin, and analysis by MALDI-TOF MS/MS. The results were confirmed by verification of the amino acid sequences of some selected peptides by MALDI-TOF MS/MS. The samples residual toxic activity was evaluated through incubation with a DNA substrate, to simulate the attack by ricin, followed by MALDI-TOF MS/MS analyses.

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Madhavan, Anitha, Arun Sachu, Nandini Sethuraman, Anil Kumar, and Jayalakshmi Vasudevapanicker. "Evaluation of Matrix-assisted laser desorption/ionization Time-of flight Mass spectrometry (MALDI TOF MS) and VITEK 2 in routine microbial identification." Ghana Medical Journal 55, no. 4 (December 1, 2021): 308–10. http://dx.doi.org/10.4314/gmj.v55i4.12.

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Background: Microbial Identification was done by phenotypic methods. VITEK-2 and Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) are now being increasingly used in laboratories.Objectives: To compare and evaluate the usefulness of MALDI-TOF MS and VITEK-2 in routine microbial identification.Methods: The performances of MALDI-TOF MS and VITEK 2 were compared for identifying microorganisms.Results: MALDI- TOF MS and VITEK-2 correctly identified 96 % (96/100) and 97% (97/100) of the isolates upto the genus level.Conclusion: MALDI TOF MS and VITEK -2 gave comparable identification and error rates. The rapid reduction in turnaround time with MALDI TOF is a significant game-changer in the field of clinical microbiology

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Tan, Zhi Lei, Yu Qiao Wei, Shuang Liang, Ran Zhang, Miao Liu, and Shi Ru Jia. "Rapid Identification of Microorganisms Isolated from Pickled Vegetables by MALDI-TOF Mass Spectrometry." Advanced Materials Research 712-715 (June 2013): 494–97. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.494.

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Matrix-assisted laser desorption/ionization time-off light mass spectrometry (MALDI-TOF MS) is increasingly used as a microbial diagnostic method for species identification of pathogens. However, MALDI-TOF MS identification of food bacteria was seldom reported. Ten strains isolated from different pickled vegetables were rapid identified by MALDI-TOF MS. The results of MALDI-TOF MS were confirmed by 16S rDNA sequencing method. Different score values in MALDI-TOF MS revealed nineLeuconostoc mesenteroides and oneStaphylococcus.Identification success at the species and genus levels was 90% (9/10) and 100% (10/10), respectively.16S rDNA sequencing results showed that nine stains were identified asLeuconostoc mesenteroides and one wasStaphylococcus saprophyticus.Results obtained demonstrate that MALDI-TOFMS is a promising method for discriminating and identifying food bacteria.

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Mareković, Ivana, Zrinka Bošnjak, Marko Jakopović, Zagorka Boras, Mateja Janković, and Sanja Popović-Grle. "Evaluation of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry in Identification of Nontuberculous Mycobacteria." Chemotherapy 61, no. 4 (2016): 167–70. http://dx.doi.org/10.1159/000442517.

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Background/Aims: Species-level identification of nontuberculous mycobacteria (NTM) is important in making decisions about the necessity and choice of antimicrobial treatment. The reason is predictable clinical significance and the susceptibility profile of specific NTM species. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is recognized as a diagnostic tool for routine identification of bacteria and yeasts in the clinical laboratory based on protein fingerprint analysis. The aim of the study was to evaluate MALDI-TOF MS in the identification of NTM. Methods: A total of 25 NTM isolates from liquid cultures were identified with both polymerase chain reaction (PCR)-based hybridization assay and MALDI-TOF MS at the University Hospital Center Zagreb. Results: PCR-based hybridization assay identified 96% (24/25) and MALDI-TOF MS 80% (20/25) of tested NTM isolates. Five isolates with no reliable MALDI-TOF MS identification belonged to the Mycobacterium avium-intracellulare complex. Seventy percent (14/20) of NTM isolates successfully identified with MALDI-TOF MS had a score higher than 2.0, indicating reliable species identification. Conclusion: MALDI-TOF MS is a promising tool for the identification of NTM. With a further improvement of the protein extraction protocol, especially regarding the M. avium-intracellulare complex, MALDI-TOF MS could be an additional standard method for identification of NTM.

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Han, Sang-Soo, Young-Su Jeong, and Sun-Kyung Choi. "Current Scenario and Challenges in the Direct Identification of Microorganisms Using MALDI TOF MS." Microorganisms 9, no. 9 (September 9, 2021): 1917. http://dx.doi.org/10.3390/microorganisms9091917.

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MALDI TOF MS-based microbial identification significantly lowers the operational costs because of minimal requirements of substrates and reagents for extraction. Therefore, it has been widely used in varied applications such as clinical, food, military, and ecological research. However, the MALDI TOF MS method is laced with many challenges including its limitation of the reference spectrum. This review briefly introduces the background of MALDI TOF MS technology, including sample preparation and workflow. We have primarily discussed the application of MALDI TOF MS in the identification of microorganisms. Furthermore, we have discussed the current trends for bioaerosol detection using MALDI TOF MS and the limitations and challenges involved, and finally the approaches to overcome these challenges.

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Oliveira, Thais Cristina de Assis, Maria Aparecida Vasconcelos Paiva Brito, Marcia Giambiagi-de Marval, Nívea Maria Vicentini, and Carla Christine Lange. "Identification of bovine mastitis pathogens using MALDI-TOF mass spectrometry in Brazil." Journal of Dairy Research 88, no. 3 (August 2021): 302–6. http://dx.doi.org/10.1017/s0022029921000595.

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AbstractIn this Research Communication we evaluate the use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify 380 bacteria isolated from cases of bovine mastitis in Brazil. MALDI-TOF MS identifications were compared to previous identifications by biochemical tests and 16S rRNA sequencing. MALDI-TOF MS achieved a typeability of 95.5%. The accuracy of MALDI-TOF MS for the identification of Staphylococcus isolates was 93.2%. The agreement between MALDI-TOF MS and biochemical identification of Streptococcus agalactiae was 96%, however, the agreement between these techniques for identifying other catalase-negative, Gram-positive cocci was lower. Agreement in identifying Gram-negative bacteria at the genus level was 90.5%. Our findings corroborate that MALDI-TOF MS is an accurate, rapid and simple technique for identifying bovine mastitis pathogens. The availability of this methodology in some research institutions would represent a significant step toward increasing the diagnosis and epidemiological studies of bovine mastitis and other animal infectious diseases in Brazil.

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Schiller, Jurgen. "MALDI-TOF MS in lipidomics." Frontiers in Bioscience 12, no. 1 (2007): 2568. http://dx.doi.org/10.2741/2255.

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Osa, Morichika, Maria Cecilia Belo, Zita Dela Merced, Annavi Marie G. Villanueva, Jaira Mauhay, Alyannah Celis, Melissa Catli, et al. "Performance of MALDI–TOF Mass Spectrometry in the Philippines." Tropical Medicine and Infectious Disease 6, no. 3 (June 26, 2021): 112. http://dx.doi.org/10.3390/tropicalmed6030112.

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Identification of the causative pathogen in infectious diseases is important for surveillance and to guide treatment. In low- and middle-income countries (LMIC), conventional culture and identification methods, including biochemical methods, are reference-standard. Biochemical methods can lack sensitivity and specificity and have slow turnaround times, causing delays in definitive therapy. Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI–TOF MS) is a rapid and accurate diagnostic method. Most studies comparing MALDI–TOF MS and biochemical methods are from high-income countries, with few reports from LMIC with tropical climates. The aim of this study was to assess the performance of MALDI–TOF MS compared to conventional methods in the Philippines. Clinical bacterial or fungal isolates were identified by both MALDI–TOF MS and automated (VITEK2) or manual biochemical methods in the San Lazaro Hospital, Metro Manila, the Philippines. The concordance between MALDI–TOF MS and automated (VITEK2) or manual biochemical methods was analyzed at the species and genus levels. In total, 3530 bacterial or fungal isolates were analyzed. The concordance rate between MALDI–TOF MS and biochemical methods was 96.2% at the species level and 99.9% at the genus level. Twenty-three isolates could not be identified by MALDI–TOF MS. In this setting, MALDI–TOF MS was accurate compared with biochemical methods, at both the genus and the species level. Additionally, MALDI–TOF MS improved the turnaround time for results. These advantages could lead to improved infection management and infection control in low- and middle-income countries, even though the initial cost is high.

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Woods, Katherine, David Beighton, and John L. Klein. "Identification of the ‘Streptococcus anginosus group’ by matrix-assisted laser desorption ionization – time-of-flight mass spectrometry." Journal of Medical Microbiology 63, no. 9 (September 1, 2014): 1143–47. http://dx.doi.org/10.1099/jmm.0.076653-0.

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Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) provides rapid, accurate and cost-effective identification of a range of bacteria and is rapidly changing the face of routine diagnostic microbiology. However, certain groups of bacteria, for example streptococci (in particular viridans or non-haemolytic streptococci), are less reliably identified by this method. We studied the performance of MALDI-TOF MS for identification of the ‘Streptococcus anginosus group’ (SAG) to species level. In total, 116 stored bacteraemia isolates identified by conventional methods as belonging to the SAG were analysed by MALDI-TOF MS. Partial 16S rRNA gene sequencing, supplemented with sialidase activity testing, was performed on all isolates to provide ‘gold standard’ identification against which to compare MALDI-TOF MS performance. Overall, 100 % of isolates were correctly identified to the genus level and 93.1 % to the species level by MALDI-TOF MS. However, only 77.6 % were correctly identified to the genus level and 59.5 % to the species level by a MALDI-TOF MS direct transfer method alone. Use of a rapid in situ extraction method significantly improved identification rates when compared with the direct transfer method (P<0.001). We recommend routine use of this method to reduce the number of time-consuming full extractions required for identification of this group of bacteria by MALDI-TOF MS in the routine diagnostic laboratory. Only 22 % (1/9) of Streptococcus intermedius isolates were reliably identified by MALDI-TOF MS to the species level, even after full extraction. MALDI-TOF MS reliably identifies S. anginosus and Streptococcus constellatus to the species level but does not reliably identify S. intermedius.

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LEI, DERU, PEIYING CHEN, XUETING CHEN, YUJIE ZONG, and XIANGYANG LI. "Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry for Identification of Microorganisms in Clinical Urine Specimens after Two Pretreatments." Polish Journal of Microbiology 70, no. 2 (May 31, 2021): 207–13. http://dx.doi.org/10.33073/pjm-2021-018.

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Rapid identification of microorganisms in urine is essential for patients with urinary tract infections (UTIs). Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been proposed as a method for the direct identification of urinary pathogens. Our purpose was to compare centrifugation-based MALDI-TOF MS and short-term culture combined with MALDI-TOF MS for the direct identification of pathogens in urine specimens. We collected 965 urine specimens from patients with suspected UTIs, 211/965 isolates were identified as positive by conventional urine culture. Compared with the conventional method, the results of centrifugation-based MALDI-TOF MS were consistent in 159/211 cases (75.4%), of which 135/159 (84.9%) had scores ≥ 2.00; 182/211 cases (86.3%) were detected using short-term culture combined with MALDI-TOF MS, of which 153/182 (84.1%) had scores ≥ 2.00. There were no apparent differences among the three methods (p = 0.135). MALDI-TOF MS appears to accelerate the microbial identification speed in urine and saves at least 24 to 48 hours compared with the routine urine culture. Centrifugation-based MALDI-TOF MS is characterized by faster identification speed; however, it is substantially affected by the number of bacterial colonies. In contrast, short-term culture combined with MALDI-TOF MS has a higher detection rate but a relatively slow identification speed. Combining these characteristics, the two methods may be effective and reliable alternatives to traditional urine culture.

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Elbehiry, Ayman, Musaad Aldubaib, Adil Abalkhail, Eman Marzouk, Ahmad ALbeloushi, Ihab Moussa, Mai Ibrahem, et al. "How MALDI-TOF Mass Spectrometry Technology Contributes to Microbial Infection Control in Healthcare Settings." Vaccines 10, no. 11 (November 8, 2022): 1881. http://dx.doi.org/10.3390/vaccines10111881.

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Healthcare settings have been utilizing matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) since 2010. MALDI-TOF MS has various benefits over the conventional method of biochemical identification, including ease of use, speed, accuracy, and low cost. This approach can solve many of the obstacles to identifying bacteria, fungi and viruses. As technology advanced, more and more databases kept track of spectra, allowing species with similar morphological, genotypic, and biochemical traits to be identified. Using MALDI-TOF MS for identification has become more accurate and quicker due to advances in sample preparation and database enrichment. Rapid sample detection and colony identification using MALDI-TOF MS have produced promising results. A key application of MALDI-TOF MS is quickly identifying highly virulent and drug-resistant diseases. Here, we present a review of the scientific literature assessing the effectiveness of MALDI-TOF MS for locating clinically relevant pathogenic bacteria, fungi, and viruses. MALDI-TOF MS is a useful strategy for locating clinical pathogens, however, it also has some drawbacks. A small number of spectra in the database and inherent similarities among organisms can make it difficult to distinguish between different species, which can result in misidentifications. The majority of the time additional testing may correct these problems, which happen very seldom. In conclusion, infectious illness diagnosis and clinical care are being revolutionized by the use of MALDI-TOF MS in the clinical microbiology laboratory.

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Chui, Huixia, Michael Chan, Drexler Hernandez, Patrick Chong, Stuart McCorrister, Alyssia Robinson, Matthew Walker, et al. "Rapid, Sensitive, and Specific Escherichia coli H Antigen Typing by Matrix-Assisted Laser Desorption Ionization–Time of Flight-Based Peptide Mass Fingerprinting." Journal of Clinical Microbiology 53, no. 8 (May 27, 2015): 2480–85. http://dx.doi.org/10.1128/jcm.00593-15.

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Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has gained popularity in recent years for rapid bacterial identification, mostly at the genus or species level. In this study, a rapid method to identify the Escherichia coli flagellar antigen (H antigen) at the subspecies level was developed using a MALDI-TOF MS platform with high specificity and sensitivity. Flagella were trapped on a filter membrane, and on-filter trypsin digestion was performed. The tryptic digests of each flagellin then were collected and analyzed by MALDI-TOF MS through peptide mass fingerprinting. Sixty-one reference strains containing all 53 H types and 85 clinical strains were tested and compared to serotyping designations. Whole-genome sequencing was used to resolve conflicting results between the two methods. It was found that DHB (2,5-dihydroxybenzoic acid) worked better than CHCA (α-cyano-4-hydroxycinnamic acid) as the matrix for MALDI-TOF MS, with higher confidence during protein identification. After method optimization, reference strains representing all 53 E. coli H types were identified correctly by MALDI-TOF MS. A custom E. coli flagellar/H antigen database was crucial for clearly identifying the E. coli H antigens. Of 85 clinical isolates tested by MALDI-TOF MS-H, 75 identified MS-H types (88.2%) matched results obtained from traditional serotyping. Among 10 isolates where the results of MALDI-TOF MS-H and serotyping did not agree, 60% of H types characterized by whole-genome sequencing agreed with those identified by MALDI-TOF MS-H, compared to only 20% by serotyping. This MALDI-TOF MS-H platform can be used for rapid and cost-effective E. coli H antigen identification, especially during E. coli outbreaks.

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Westblade, Lars F., Omai B. Garner, Karen MacDonald, Constance Bradford, David H. Pincus, A. Brian Mochon, Rebecca Jennemann, et al. "Assessment of Reproducibility of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Bacterial and Yeast Identification." Journal of Clinical Microbiology 53, no. 7 (April 29, 2015): 2349–52. http://dx.doi.org/10.1128/jcm.00187-15.

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Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (MS) has revolutionized the identification of clinical bacterial and yeast isolates. However, data describing the reproducibility of MALDI-TOF MS for microbial identification are scarce. In this study, we show that MALDI-TOF MS-based microbial identification is highly reproducible and can tolerate numerous variables, including differences in testing environments, instruments, operators, reagent lots, and sample positioning patterns. Finally, we reveal that samples of bacterial and yeast isolates prepared for MALDI-TOF MS identification can be repeatedly analyzed without compromising organism identification.

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Kaleta, Erin J., Andrew E. Clark, Abdessalam Cherkaoui, Vicki H. Wysocki, Elizabeth L. Ingram, Jacques Schrenzel, and Donna M. Wolk. "Comparative Analysis of PCR–Electrospray Ionization/Mass Spectrometry (MS) and MALDI-TOF/MS for the Identification of Bacteria and Yeast from Positive Blood Culture Bottles." Clinical Chemistry 57, no. 7 (July 1, 2011): 1057–67. http://dx.doi.org/10.1373/clinchem.2011.161968.

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BACKGROUND Emerging technologies for rapid identification of microbes demonstrate a shift from traditional biochemical and molecular testing algorithms toward methods using mass spectrometry (MS) for the semiquantitative analysis of microbial proteins and genetic elements. This study was performed to assess the diagnostic accuracy of 2 such technologies, PCR–electrospray ionization (ESI)/MS and MALDI-TOF/MS, with respect to phenotypic and biochemical profiling as a reference standard method. A positive challenge set of blood culture bottles was used to compare PCR-ESI/MS and MALDI-TOF/MS performance on a matched set of samples. METHODS We performed characterization of bloodstream infections from blood cultures using the Ibis T5000 PCR-ESI/MS and the Bruker MALDI Biotyper 2.0 (MALDI-TOF/MS) platforms for microbial identification. Diagnostic accuracy was determined by independent comparison of each method to phenotypic and biochemical characterization with Vitek2 analysis as the reference standard identification. RESULTS The diagnostic accuracy, represented as positive agreement, at the genus level was 0.965 (0.930–0.984) for PCR-ESI/MS and 0.969 (0.935–0.987) for MALDI-TOF/MS, and at the species level was 0.952 (0.912–0.974) with PCR-ESI/MS and 0.943 (0.902–0.968) for MALDI-TOF/MS. No statistically significant difference was found between PCR-ESI/MS and MALDI-TOF/MS in the ability to rapidly identify microorganisms isolated from blood culture. CONCLUSIONS Our results demonstrate that PCR-ESI/MS and MALDI-TOF/MS are equivalent in their ability to characterize bloodstream infections with respect to the reference standard, and highlight key differences in the methods that allow for each method to have a unique niche as a tool for rapid identification of microbes in blood cultures.

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Hortin, Glen L. "The MALDI-TOF Mass Spectrometric View of the Plasma Proteome and Peptidome." Clinical Chemistry 52, no. 7 (July 1, 2006): 1223–37. http://dx.doi.org/10.1373/clinchem.2006.069252.

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Abstract Background: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and the related technique, surface-enhanced laser desorption/ionization (SELDI)-TOF MS, are being applied widely to analyze serum or plasma specimens for potential disease markers. Methods: Reports on the basic principles and applications of MALDI-TOF MS were reviewed and related to information on abundance and masses of major plasma proteins. Outcomes: MALDI-TOF MS is a particle-counting method that responds to molar abundance, and ranking of plasma proteins by molar abundance increases the rank of small proteins relative to traditional ranking by mass abundance. Detectors for MALDI-TOF MS augment the bias for detecting smaller components by yielding stronger signals for an equivalent number of small vs large ions. Consequently, MALDI-TOF MS is a powerful tool for surveying small proteins and peptides comprising the peptidome or fragmentome, opening this new realm for analysis. It is complementary to techniques such as electrophoresis and HPLC, which have a bias for detecting larger molecules. Virtually all of the potential markers identified by MALDI-TOF MS to date represent forms of the most abundant plasma proteins. Conclusions: Analyses of serum or plasma by MALDI-TOF MS provide new information mainly about small proteins and peptides with high molar abundance. The spectrum of observed proteins and peptides suggests value for applications such as assessment of cardiovascular risk, nutritional status, liver injury, kidney failure, and systemic immune responses rather than early detection of cancer. Extending analysis by MALDI-TOF MS to lower abundance components, such as markers for early-stage cancers, probably will require more extensive specimen fractionation before analysis.

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Beganovic, Maya, Michael Costello, and Sarah M. Wieczorkiewicz. "Effect of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI-TOF MS) Alone versus MALDI-TOF MS Combined with Real-Time Antimicrobial Stewardship Interventions on Time to Optimal Antimicrobial Therapy in Patients with Positive Blood Cultures." Journal of Clinical Microbiology 55, no. 5 (February 22, 2017): 1437–45. http://dx.doi.org/10.1128/jcm.02245-16.

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ABSTRACT Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) decreases the time to organism identification and improves clinical and financial outcomes. The purpose of this study was to evaluate the impact of MALDI-TOF MS alone versus MALDI-TOF MS combined with real-time, pharmacist-driven, antimicrobial stewardship (AMS) intervention on patient outcomes. This single-center, pre-post, quasiexperimental study evaluated hospitalized patients with positive blood cultures identified via MALDI-TOF MS combined with prospective AMS intervention compared to a control cohort with MALDI-TOF MS identification without AMS intervention. AMS intervention included: real-time MALDI-TOF MS pharmacist notification and prospective AMS provider feedback. The primary outcome was the time to optimal therapy (TTOT). A total of 252 blood cultures, 126 in each group, were included in the final analysis. MALDI-TOF MS plus AMS intervention significantly reduced the overall TTOT (75.17 versus 43.06 h; P < 0.001), the Gram-positive contaminant TTOT (48.21 versus 11.75 h; P < 0.001), the Gram-negative infection (GNI) TTOT (71.83 versus 35.98 h; P < 0.001), and the overall hospital length of stay (LOS; 15.03 versus 9.02 days; P = 0.021). The TTOT for Gram-positive infection (GPI) was improved (64.04 versus 41.61 h; P = 0.082). For GPI, the hospital LOS (14.64 versus 10.31 days; P = 0.002) and length of antimicrobial therapy 24.30 versus 18.97 days; P = 0.018) were reduced. For GNI, the time to microbiologic clearance (51.13 versus 34.51 h; P < 0.001), the hospital LOS (15.40 versus 7.90 days; P = 0.027), and the intensive care unit LOS (5.55 versus 1.19 days; P = 0.035) were reduced. To achieve optimal outcomes, rapid identification with MALDI-TOF MS combined with real-time AMS intervention is more impactful than MALDI-TOF MS alone.

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Sepiashvili, Lusia, Mindy C. Kohlhagen, Melissa R. Snyder, Maria A. V. Willrich, John R. Mills, Angela Dispenzieri, and David L. Murray. "Direct Detection of Monoclonal Free Light Chains in Serum by Use of Immunoenrichment-Coupled MALDI-TOF Mass Spectrometry." Clinical Chemistry 65, no. 8 (August 1, 2019): 1015–22. http://dx.doi.org/10.1373/clinchem.2018.299461.

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Abstract BACKGROUND Free light chain (FLC) quantification is the most analytically sensitive blood-based method commercially available to diagnose and monitor patients with plasma cell disorders (PCDs). However, instead of directly detecting monoclonal FLCs (mFLCs), FLC assays indirectly assess clonality based on quantifying κ and λ FLCs and determination of the к/λ FLC ratio. Often an abnormal FLC ratio is the only indication of a PCD, and confirmation by a direct method increases diagnostic confidence. The aim of this study was to develop an analytically sensitive method for direct detection of mFLCs. METHODS Patient sera (n = 167) previously assessed by nephelometric FLC quantification and immunofixation electrophoresis (IFE) were affinity enriched for IgG, IgA, and total and free κ and λ light chains and subjected to MALDI-TOF MS. Relative analytical sensitivity of these methods was determined using serially diluted sera containing mFLCs. RESULTS In sera with abnormal FLC ratios (n = 127), 43% of monoclonal proteins were confirmed by IFE, 57% by MALDI-TOF MS without FLC enrichment, and 87% with FLC enrichment MALDI-TOF MS. In sera with normal FLC ratios (n = 40), the FLC MALDI-TOF MS method identified 1 patient with an mFLC. Serial dilution and analysis of mFLC containing sera by IFE, nephelometry, and FLC MALDI-TOF MS demonstrated that FLC MALDI-TOF MS analysis had the highest analytical sensitivity. CONCLUSIONS FLC immunoenrichment coupled to MALDI-TOF MS enables direct detection of mFLCs and significantly increases the confirmation of abnormal serum FLC ratios over IFE and MALDI-TOF MS without FLC enrichment, thereby providing added confidence for diagnosing FLC PCDs.

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Viana, Roberta Oliveira, Karina Teixeira Magalhães-Guedes, Disney Ribeiro Dias, and Rosane Freitas Schwan. "Use of Maldi-Tof MS biosensor in microbial assessment of Brazilian kefir grains." Revista Ceres 66, no. 1 (February 2019): 72–76. http://dx.doi.org/10.1590/0034-737x201966010010.

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ABSTRACT The aim of this study was to evaluate the use of Maldi-Tof MS biosensor in microbial assessment of Brazilian kefir grains. Maldi-Tof MS is a new methodology for the rapid diagnosis of microorganisms. A total of 358 microorganisms were isolated, 31 were yeasts and 327 were bacteria (divided into lactic and acetic bacteria). Microbial colonies were grown in Luria-Bertani agar medium and incubated at 35 °C for 18h and used in the identification of species by Maldi-Tof MS. The microbial population identified in Brazilian kefir grains was Lactobacillus paracasei, Saccharomyces cerevisiae, Lactobacillus plantarum, Acetobacter pasteurianus, and Acetobacter syzygii. This study demonstrated a rapid and accurate identification of the Brazilian kefir grains microorganisms using the Maldi-Tof MS biosensor. In conclusion, the Maldi-Tof MS technology can facilitate the microbiological control in a fermentation process using kefir grains as starter cultures.

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Paziani, Mario Henrique, Ludmilla Tonani Carvalho, Marcia de Souza Carvalho Melhem, Margarete Teresa Gottardo de Almeida, Maria Emilia Nadaletto Bonifácio da Silva, Roberto Martinez, Cledir Santos, and Marcia Regina von Zeska Kress. "First Comprehensive Report of Clinical Fusarium Strains Isolated in the State of Sao Paulo (Brazil) and Identified by MALDI-TOF MS and Molecular Biology." Microorganisms 8, no. 1 (December 31, 2019): 66. http://dx.doi.org/10.3390/microorganisms8010066.

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The aim of this study was to compare the performance of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), phenotypic and molecular methods for the identification of Fusarium species complexes isolated from clinical cases in the State of Sao Paulo (Brazil) between the years 2001 and 2017. Sequencing of ITS region of ribosomal DNA and elongation factor 1 alpha gene (ET1α) were used as reference method in the analysis of a total of 108 Fusarium spp. clinical strains isolated from human hosts with superficial and systemic infections. Agreement between MALDI-TOF-MS and molecular data was observed for 97 out of 108 clinical isolates (89.8%), whereas five (4.6%) and six (5.5%) clinical isolates were misidentified and were not identified by MALDI-TOF MS, respectively. ITS region sequences and MALDI-TOF MS mass spectra identified and grouped correctly most of Fusarium clinical isolates at species complex level. This investigation highlights the potential of MALDI-TOF MS technique as a fast and cost-efficient alternative for clinical Fusarium identification. However, MALDI-TOF MS requires a more accurate and larger database. This work is the first comprehensive report for Fusarium population, based on phenotypic analyses, proteomic profile by MALDI-TOF and phylogenetic analyses of Fusarium species complexes isolated from clinical cases in the State of Sao Paulo, Brazil.

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Tsuchida, Sachio, Hiroshi Umemura, and Tomohiro Nakayama. "Current Status of Matrix-Assisted Laser Desorption/Ionization–Time-of-Flight Mass Spectrometry (MALDI-TOF MS) in Clinical Diagnostic Microbiology." Molecules 25, no. 20 (October 17, 2020): 4775. http://dx.doi.org/10.3390/molecules25204775.

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Mass spectrometry (MS), a core technology for proteomics and metabolomics, is currently being developed for clinical applications. The identification of microorganisms in clinical samples using matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry (MALDI-TOF MS) is a representative MS-based proteomics application that is relevant to daily clinical practice. This technology has the advantages of convenience, speed, and accuracy when compared with conventional biochemical methods. MALDI-TOF MS can shorten the time used for microbial identification by about 1 day in routine workflows. Sample preparation from microbial colonies has been improved, increasing the accuracy and speed of identification. MALDI-TOF MS is also used for testing blood, cerebrospinal fluid, and urine, because it can directly identify the microorganisms in these liquid samples without prior culture or subculture. Thus, MALDI-TOF MS has the potential to improve patient prognosis and decrease the length of hospitalization and is therefore currently considered an essential tool in clinical microbiology. Furthermore, MALDI-TOF MS is currently being combined with other technologies, such as flow cytometry, to expand the scope of clinical applications.

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Taučer-Kapteijn, Maja, Gertjan Medema, and Wim Hoogenboezem. "Comparison between Rapid ID 32 Strep System, Matrix Assisted Laser Desorption Ionisation–Time of Flight Mass Spectrometry and 16S rRNA gene sequence analysis for the species identification of Enterococcus spp. isolated from water." Water Supply 13, no. 5 (September 1, 2013): 1383–89. http://dx.doi.org/10.2166/ws.2013.152.

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Matrix-Assisted Laser Desorption Ionisation–Time of Flight Mass Spectrometry (MALDI–TOF MS) has increasingly been used for rapid and reliable identification of clinically relevant micro-organisms. To establish the applicability of this technique in (drinking) water quality analysis, the MALDI–TOF MS identification results for Enterococcus spp. isolated from various water environments were compared with those obtained using the commercial Rapid 32 ID Strep system. One hundred and one bacterial isolates were isolated from various types of water and determined as enterococci on the basis of their growth on Slanetz-Bartley agar in typical colonies. The isolates were identified by MALDI–TOF MS and the commercial biochemical test Rapid 32 ID Strep. Isolates yielding in discrepant identifications were genotyped using 16S rRNA gene sequence analysis. For 86 isolates (85%), the results of Rapid ID 32 Strep were identical to those obtained with MALDI–TOF MS. Six isolates were impossible to be classified by means of the Rapid 32 ID Strep test. And for eight out of a total of nine discrepant results (89%), the 16S analyses confirmed the MALDI–TOF MS identification. MALDI–TOF MS produced highly reproducible results. These results indicated that the use of two different culture media had no effect on the identification. In addition, no significant differences (p = 0.32; n = 20) were evident between the scores obtained from a 20-fold measurement of the same isolate. The results of this study showed that MALDI–TOF MS identification (Bruker) is a reliable method for identifying E. faecium, E. faecalis, E. durans, E. hirae and E. casseliflavus isolated from water samples. E. mundtii and E. moraviensis were not included in the Rapid 32 ID Strep database and could therefore not be identified using that test set. However, MALDI–TOF MS and 16S identified all six isolates as members of these species.

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Ngoy, Steve, Adama Zan Diarra, Anne Laudisoit, Guy-Crispin Gembu, Erik Verheyen, Onésime Mubenga, Sylvestre Gambalemoke Mbalitini, Pascal Baelo, Maureen Laroche, and Philippe Parola. "Using MALDI-TOF mass spectrometry to identify ticks collected on domestic and wild animals from the Democratic Republic of the Congo." Experimental and Applied Acarology 84, no. 3 (June 19, 2021): 637–57. http://dx.doi.org/10.1007/s10493-021-00629-z.

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AbstractMatrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) has recently emerged as an alternative to morphological and molecular tools to identify tick species. In this study, we set out to evaluate and confirm the ability of MALDI-TOF MS to identify different species of ticks collected in the Democratic Republic of the Congo and preserved in 70% ethanol. A total of 575 ticks, of which 530 were collected from domestic pigs and 45 from wild animals, were subjected to MALDI-TOF MS analysis to evaluate the intraspecies reproducibility and interspecies specificity of MS profiles obtained from the different species. Morphologically, the ticks belonged to seven different species, namely Rhipicephalus complanatus, Rhipicephalus congolensis, Haemaphysalis muhsamae, Ixodes cumulatimpunctatus, Amblyomma exornatum, Amblyomma compressum and an unidentified Rhipicephalus sp. A total of 535/575 (93%) of the spectra obtained were of good enough quality to be used for our analyses. Our home-made MALDI-TOF MS arthropod database was upgraded with spectra obtained from between one and five randomly selected specimens per species. For these reference specimens, molecular identification of the ticks was also made using 16S, 12S rDNA genes and the Cox1 mtDNA gene sequencing. The remaining good quality spectra were then queried against the upgraded MALDI-TOF MS database, showing that 100% were in agreement with the morphological identification, with logarithmic score values (LSVs) between 1.813 and 2.51. The consistency between our morphological, molecular and MALDI-TOF MS identification confirms the capability and precision of MALDI-TOF MS for tick identification.

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Nie, Shuping, Baoyu Tian, Xiaowei Wang, David H. Pincus, Martin Welker, Kathleen Gilhuley, Xuedong Lu, Yiping W. Han, and Yi-Wei Tang. "Fusobacterium nucleatum Subspecies Identification by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry." Journal of Clinical Microbiology 53, no. 4 (February 4, 2015): 1399–402. http://dx.doi.org/10.1128/jcm.00239-15.

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We explored the use of matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) for identification ofFusobacterium nucleatumsubspecies. MALDI-TOF MS spectra of fiveF. nucleatumsubspecies (animalis,fusiforme,nucleatum,polymorphum, andvincentii) were analyzed and divided into four distinct clusters, including subsp.animalis,nucleatum,polymorphum, andfusiforme/vincentii. MALDI-TOF MS with the modified SARAMIS database further correctly identified 28 of 34F. nucleatumclinical isolates to the subspecies level.

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Buckwalter, S. P., S. L. Olson, B. J. Connelly, B. C. Lucas, A. A. Rodning, R. C. Walchak, S. M. Deml, S. L. Wohlfiel, and N. L. Wengenack. "Evaluation of Matrix-Assisted Laser Desorption Ionization−Time of Flight Mass Spectrometry for Identification of Mycobacterium species, Nocardia species, and Other Aerobic Actinomycetes." Journal of Clinical Microbiology 54, no. 2 (December 4, 2015): 376–84. http://dx.doi.org/10.1128/jcm.02128-15.

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The value of matrix-assisted laser desorption ionization−time of flight mass spectrometry (MALDI-TOF MS) for the identification of bacteria and yeasts is well documented in the literature. Its utility for the identification of mycobacteria andNocardiaspp. has also been reported in a limited scope. In this work, we report the specificity of MALDI-TOF MS for the identification of 162Mycobacteriumspecies and subspecies, 53Nocardiaspecies, and 13 genera (totaling 43 species) of other aerobic actinomycetes using both the MALDI-TOF MS manufacturer's supplied database(s) and a custom database generated in our laboratory. The performance of a simplified processing and extraction procedure was also evaluated, and, similar to the results in an earlier literature report, our viability studies confirmed the ability of this process to inactivateMycobacterium tuberculosisprior to analysis. Following library construction and the specificity study, the performance of MALDI-TOF MS was directly compared with that of 16S rRNA gene sequencing for the evaluation of 297 mycobacteria isolates, 148Nocardiaspecies isolates, and 61 other aerobic actinomycetes isolates under routine clinical laboratory working conditions over a 6-month period. MALDI-TOF MS is a valuable tool for the identification of these groups of organisms. Limitations in the databases and in the ability of MALDI-TOF MS to rapidly identify slowly growing mycobacteria are discussed.

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Jagannadham, Medicharla V., and Ramakrishnan Nagaraj. "Detecting the Site of Phosphorylation in Phosphopeptides without Loss of Phosphate Group Using MALDI TOF Mass Spectrometry." Analytical Chemistry Insights 3 (January 2008): ACI.S497. http://dx.doi.org/10.4137/aci.s497.

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Phosphopeptides with one and four phosphate groups were characterized by MALDI mass spectrometry. The molecular ion of monophosphopeptide could be detected both as positive and negative ions by MALDI TOF with delayed extraction (DE) and in the reflector mode. The tetraphospho peptide could be detected in linear mode. When MS/MS spectra of the monophospho peptides were obtained in a MALDI TOF TOF instrument by CID, b and y ions with the intact phosphate group were observed, in addition the b and y ions without the phosphate group. Our study indicates that it is possible to detect phosphorylated peptides with out the loss of phosphate group by MALDI TOF as well as MALDI TOF TOF instruments with delayed extraction and in the reflector mode.

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Tonacini, Jenna, Dario Stephan, Guido Vogel, Marc-André Avondet, Franka Kalman, Julien Crovadore, François Lefort, and Bruno Schnyder. "Intact Staphylococcus Enterotoxin SEB from Culture Supernatant Detected by MALDI-TOF Mass Spectrometry." Toxins 11, no. 2 (February 9, 2019): 101. http://dx.doi.org/10.3390/toxins11020101.

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Routine identification of pathogens by MALDI-TOF MS (matrix-assisted laser desorption ionisation time-of-flight mass spectrometry) is based on the fingerprint of intracellular proteins. This work evaluated the use of MALDI-TOF MS for the identification of extracellular pathogen factors. A Staphylococcus aureus isolate from a food contaminant was exponentially grown in liquid cultures. Secreted proteins were collected using methanol– chloroform precipitation and analysed by MALDI-TOF MS. A main peak m/z 28,250 was demonstrated, which was identified as S.aureus enterotoxin type B (SEB) by using the pure authentic SEB reference of 28.2 kDa and by amino acid sequence analysis. SEB was also detected in this intact form following pasteurization and cooking treatments. Further application of the elaborated MALDI-TOF MS protocol resulted in the detection of SEA at m/z 27,032 and SEC at m/z 27,629. In conclusion, a simple sample preparation from S.aureus cultures and an easy-to-perform identification of pathogen factors SE in intact form represents a promising next-generation application of MALDI-TOF MS.

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Petkovic, Marijana, Jurgen Schiller, Matthias Müller, Klaus Arnold, and Jurgen Arnhold. "Investigations of the lysophospholipid composition of human neutrophils under different stimulation conditions by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry." Journal of the Serbian Chemical Society 67, no. 3 (2002): 149–63. http://dx.doi.org/10.2298/jsc0203149p.

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Matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS) is usually used for the analyses of proteins carbohydrates and oligonucleotides. In spite of the number of advantages that MALDI-TOF MS exhibits for lipid analysis, this method has not often been applied in this field. In this paper we have extended our previous studies on the suitability of MALDI-TOF MS for the investigation of changes in the content of lipid-derived second messengers in organic extracts of human neutrophils. Qualitative differences in the lysophospholipid composition in organic extracts of the human neutrophils under different stimulation conditions could be easily observed by MALDI-TOF MS. Although there are still some methodological problems to be solved before this method can be routinely applied for the quantification of different lipid classes in complex biological mixtures (such as organic extracts of human neutrophils) it is shown here that MALDI-TOF MS possesses the capability to be used as a simple screening method for the investigation of the content of lipid-derived second messengers and of signalling pathways in cells.

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Lawton, Samantha J., Allison M. Weis, Barbara A. Byrne, Heather Fritz, Conor C. Taff, Andrea K. Townsend, Bart C. Weimer, Aslı Mete, Sarah Wheeler, and Walter M. Boyce. "Comparative analysis of Campylobacter isolates from wild birds and chickens using MALDI-TOF MS, biochemical testing, and DNA sequencing." Journal of Veterinary Diagnostic Investigation 30, no. 3 (March 12, 2018): 354–61. http://dx.doi.org/10.1177/1040638718762562.

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Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was compared to conventional biochemical testing methods and nucleic acid analyses (16S rDNA sequencing, hippurate hydrolysis gene testing, whole genome sequencing [WGS]) for species identification of Campylobacter isolates obtained from chickens ( Gallus gallus domesticus, n = 8), American crows ( Corvus brachyrhynchos, n = 17), a mallard duck ( Anas platyrhynchos, n = 1), and a western scrub-jay ( Aphelocoma californica, n = 1). The test results for all 27 isolates were in 100% agreement between MALDI-TOF MS, the combined results of 16S rDNA sequencing, and the hippurate hydrolysis gene PCR ( p = 0.0027, kappa = 1). Likewise, the identifications derived from WGS from a subset of 14 isolates were in 100% agreement with the MALDI-TOF MS identification. In contrast, biochemical testing misclassified 5 isolates of C. jejuni as C. coli, and 16S rDNA sequencing alone was not able to differentiate between C. coli and C. jejuni for 11 sequences ( p = 0.1573, kappa = 0.0857) when compared to MALDI-TOF MS and WGS. No agreement was observed between MALDI-TOF MS dendrograms and the phylogenetic relationships revealed by rDNA sequencing or WGS. Our results confirm that MALDI-TOF MS is a fast and reliable method for identifying Campylobacter isolates to the species level from wild birds and chickens, but not for elucidating phylogenetic relationships among Campylobacter isolates.

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Shao, Jin, Zhe Wan, Ruoyu Li, and Jin Yu. "Species Identification and Delineation of Pathogenic Mucorales by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry." Journal of Clinical Microbiology 56, no. 4 (February 7, 2018): e01886-17. http://dx.doi.org/10.1128/jcm.01886-17.

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ABSTRACT This study aimed to validate the effectiveness of matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS)-based identification of filamentous fungi of the order Mucorales. A total of 111 isolates covering six genera preserved at the Research Center for Medical Mycology of Peking University were selected for MALDI-TOF MS analysis. We emphasized the study of 23 strains of Mucor irregularis predominantly isolated from patients in China. We first used the Bruker Filamentous Fungi library (v1.0) to identify all 111 isolates. To increase the identification rate, we created a compensatory in-house database, the Beijing Medical University (BMU) database, using 13 reference strains covering 6 species, including M. irregularis, Mucor hiemalis, Mucor racemosus, Cunninghamella bertholletiae, Cunninghamella phaeospora, and Cunninghamella echinulata. All 111 isolates were then identified by MALDI-TOF MS using a combination of the Bruker library and BMU database. MALDI-TOF MS identified 55 (49.5%) and 74 (66.7%) isolates at the species and genus levels, respectively, using the Bruker Filamentous Fungi library v1.0 alone. A combination of the Bruker library and BMU database allowed MALDI-TOF MS to identify 90 (81.1%) and 111 (100%) isolates at the species and genus levels, respectively, with a significantly increased accuracy rate. MALDI-TOF MS poorly identified Mucorales when the Bruker library was used alone due to its lack of some fungal species. In contrast, this technique perfectly identified M. irregularis after main spectrum profiles (MSPs) of relevant reference strains were added to the Bruker library. With an expanded Bruker library, MALDI-TOF MS is an effective tool for the identification of pathogenic Mucorales.

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Zhong, Xiao Yan, and Wolfgang Holzgreve. "MALDI-TOF MS in Prenatal Genomics." Transfusion Medicine and Hemotherapy 36, no. 4 (2009): 263–72. http://dx.doi.org/10.1159/000223098.

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Baudler, Liane, Sandra Scheufen, Luisa Ziegler, Franca Möller Palau-Ribes, Christa Ewers, and Michael Lierz. "Identification and differentiation of avianMycoplasmaspecies using MALDI-TOF MS." Journal of Veterinary Diagnostic Investigation 31, no. 4 (June 11, 2019): 620–24. http://dx.doi.org/10.1177/1040638719856932.

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The identification of avian Mycoplasma spp. by conventional immunologic, phenotypic, and molecular methods can be demanding and time-consuming. We evaluated MALDI-TOF MS for its suitability to identify avian mycoplasmas at the species level. We generated a mycoplasma spectral database of 36 main spectrum profiles (MSPs) representing 23 avian Mycoplasma spp. using 23 type and reference strains, 1 live vaccine strain, and 8 clinical isolates. We then used 112 avian Mycoplasma clinical isolates of different avian mycoplasmas, 4 Mycoplasma live vaccine strains, and 1 Mycoplasma type strain, previously cultured and identified to the species level by molecular methods, to evaluate the MSP database. Protein extraction and MALDI-TOF MS analysis were performed with a maximum of 3 repetitions per isolate. MALDI-TOF MS resulted in accurate species-level identification with a score of ≥2.0 for 112 of 117 (96%) isolates. The MALDI-TOF MS analysis of 4 of 5 isolates that did not yield a score of ≥2.0 resulted in best-match identifications that were still concordant at species level with the molecular method used for previous identification. Therefore, MALDI-TOF MS is a promising tool for reliable identification of avian Mycoplasma spp.

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Wang, Chia-Chen, Yin-Hung Lai, Yu-Meng Ou, Huan-Tsung Chang, and Yi-Sheng Wang. "Critical factors determining the quantification capability of matrix-assisted laser desorption/ionization– time-of-flight mass spectrometry." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, no. 2079 (October 28, 2016): 20150371. http://dx.doi.org/10.1098/rsta.2015.0371.

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Quantitative analysis with mass spectrometry (MS) is important but challenging. Matrix-assisted laser desorption/ionization (MALDI) coupled with time-of-flight (TOF) MS offers superior sensitivity, resolution and speed, but such techniques have numerous disadvantages that hinder quantitative analyses. This review summarizes essential obstacles to analyte quantification with MALDI-TOF MS, including the complex ionization mechanism of MALDI, sensitive characteristics of the applied electric fields and the mass-dependent detection efficiency of ion detectors. General quantitative ionization and desorption interpretations of ion production are described. Important instrument parameters and available methods of MALDI-TOF MS used for quantitative analysis are also reviewed. This article is part of the themed issue ‘Quantitative mass spectrometry’.

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Íñigo, Melania, Andreu Coello, Gema Fernández-Rivas, Belén Rivaya, Jessica Hidalgo, María Dolores Quesada, and Vicente Ausina. "Direct Identification of Urinary Tract Pathogens from Urine Samples, Combining Urine Screening Methods and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry." Journal of Clinical Microbiology 54, no. 4 (January 27, 2016): 988–93. http://dx.doi.org/10.1128/jcm.02832-15.

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Early diagnosis of urinary tract infections (UTIs) is essential to avoid inadequate or unnecessary empirical antibiotic therapy. Microbiological confirmation takes 24 to 48 h. The use of screening methods, such as cytometry and automated microscopic analysis of urine sediment, allows the rapid prediction of negative samples. In addition, matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a widely established technique in clinical microbiology laboratories used to identify microorganisms. We evaluated the ability of MALDI-TOF MS to identify microorganisms from direct urine samples and the predictive value of automated analyzers for the identification of microorganisms in urine by MALDI-TOF MS. A total of 451 urine samples from patients with suspected UTIs were first analyzed using the Sysmex UF-1000iflow cytometer, an automatic sediment analyzer with microscopy (SediMax), culture, and then processed by MALDI-TOF MS with a simple triple-centrifuged procedure to obtain a pellet that was washed and centrifuged and finally applied directly to the MALDI-TOF MS plate. The organisms in 336 samples were correctly identified, mainly those with Gram-negative bacteria (86.10%). No microorganisms were misidentified, and noCandidaspp. were correctly identified. Regarding the data from autoanalyzers, the best bacteriuria cutoffs were 1,000 and 200 U/μl for UF-1000iand SediMax, respectively. It was concluded that the combination of a urine screening method and MALDI-TOF MS provided a reliable identification from urine samples, especially in those containing Gram-negative bacteria.

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Fonseca, Mallika, Sarala Menon, Praveen Rahi, Prachi Patekar, and Abhay S. Chowdhary. "MALDI-TOF MS: the proteomic approach, the future of fungal identification in India." International Journal of Research in Medical Sciences 8, no. 7 (June 26, 2020): 2575. http://dx.doi.org/10.18203/2320-6012.ijrms20202898.

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Background: India, being a country where fungal infections are rampant, is urgently in need of effective tools for early and accurate diagnosis of fungal infections. Matrix-assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS) is a recent method which has shown potential in identifying clinically important bacterial pathogens as well as clinically important fungi. The main objective of this study was to compare the utility of MALDI-TOF MS for the identification of fungi against that of conventional methods.Methods: The project was carried out in a tertiary care government hospital in India. Fifty clinical isolates comprising mainly various yeast species were subjected to conventional identification (Phenotypic) as well as MALDI-TOF-MS. Their results were further compared.Results: MALDI-TOF MS showed a high concordance with conventional methods while identifying species like C. albicans, C. tropicalis, C. parapsilosis and C. neoformans, although the concordance for species such as Rhodotorula and Trichosporon could only be matched up to genus level.Conclusions: MALDI-TOF MS-based identification is both a rapid and a viable tool for identification of clinically relevant yeast species with good correlation to conventional methods and a quick turnaround time.

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Darie-Ion, Laura, Danielle Whitham, Madhuri Jayathirtha, Yashveen Rai, Anca-Narcisa Neagu, Costel C. Darie, and Brînduşa Alina Petre. "Applications of MALDI-MS/MS-Based Proteomics in Biomedical Research." Molecules 27, no. 19 (September 21, 2022): 6196. http://dx.doi.org/10.3390/molecules27196196.

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Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is one of the most widely used techniques in proteomics to achieve structural identification and characterization of proteins and peptides, including their variety of proteoforms due to post-translational modifications (PTMs) or protein–protein interactions (PPIs). MALDI-MS and MALDI tandem mass spectrometry (MS/MS) have been developed as analytical techniques to study small and large molecules, offering picomole to femtomole sensitivity and enabling the direct analysis of biological samples, such as biofluids, solid tissues, tissue/cell homogenates, and cell culture lysates, with a minimized procedure of sample preparation. In the last decades, structural identification of peptides and proteins achieved by MALDI-MS/MS helped researchers and clinicians to decipher molecular function, biological process, cellular component, and related pathways of the gene products as well as their involvement in pathogenesis of diseases. In this review, we highlight the applications of MALDI ionization source and tandem approaches for MS for analyzing biomedical relevant peptides and proteins. Furthermore, one of the most relevant applications of MALDI-MS/MS is to provide “molecular pictures”, which offer in situ information about molecular weight proteins without labeling of potential targets. Histology-directed MALDI-mass spectrometry imaging (MSI) uses MALDI-ToF/ToF or other MALDI tandem mass spectrometers for accurate sequence analysis of peptide biomarkers and biological active compounds directly in tissues, to assure complementary and essential spatial data compared with those obtained by LC-ESI-MS/MS technique.

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Fall, Fatou Kiné, Maureen Laroche, Hervé Bossin, Didier Musso, and Philippe Parola. "Performance of MALDI-TOF Mass Spectrometry to Determine the Sex of Mosquitoes and Identify Specific Colonies from French Polynesia." American Journal of Tropical Medicine and Hygiene 104, no. 5 (May 5, 2021): 1907–16. http://dx.doi.org/10.4269/ajtmh.20-0031.

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ABSTRACTMosquitoes are the main arthropod vectors of human pathogens. The current methods for mosquito identification include morphological and molecular methods. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), now routinely used for bacterial identification, has recently emerged in the field of entomology. The aim of this study was to use MALDI-TOF MS to identify mosquito colonies from French Polynesia. Five hundred specimens from French Polynesia belonging to three species, Aedes aegypti, Aedes polynesiensis, and Culex quinquefasciatus, were included in the study. Testing the legs of these mosquitoes by MALDI-TOF MS revealed a 100% correct identification of all specimens at the species level. The MALDI-TOF MS profiles obtained allowed differentiation of male from female mosquitoes and the specific identification of female mosquito colonies of the same species but different geographic origin.

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ZHU, SHA, STEFAN RATERING, SYLVIA SCHNELL, and RON WACKER. "Matrix-Assisted Laser Desorption and Ionization–Time-of-Flight Mass Spectrometry, 16S rRNA Gene Sequencing, and API 32E for Identification of Cronobacter spp.: A Comparative Study." Journal of Food Protection 74, no. 12 (December 1, 2011): 2182–87. http://dx.doi.org/10.4315/0362-028x.jfp-11-205.

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Twenty-two isolates of the family Enterobacteriaceae, with focus on Cronobacter isolated from infant formula and the environment of milk powder plants, were comparatively identified using API 32E (bioMérieux, Marcy l'Etoile, France), 16S rRNA gene sequencing (Accugenix, Newark, USA), and matrix-assisted laser desorption and ionization–time-of-flight mass spectrometry (MALDI-TOF MS; Mabritec, Riehen, Switzerland and AnagnosTec, Potsdam, Germany). With API 32E, 22% of the isolates were assigned to species, 64% were assigned to a genus, and 14% could not be discriminated at any taxonomic level. Both 16S rRNA gene sequencing and MALDI-TOF MS assigned 100% of the isolates to species, but the identifications based on MALDI-TOF MS results were more discriminating and unequivocal. Our data indicate that MALDI-TOF MS provides the most rapid and unambiguous identification of Cronobacter and closely related Enterobacteriaceae isolates.

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Chun, Lindsay Y., Laura Dolle Molle, Olaf Schneewind, Dominique Missiakas, Kathleen G. Beavis, and Dimitra Skondra. "Rapid Pathogen Identification With Direct Application of MALDI-TOF Mass Spectrometry on an Endophthalmitis Vitreous Sample Without Prior Culture." Journal of VitreoRetinal Diseases 3, no. 4 (June 10, 2019): 255–59. http://dx.doi.org/10.1177/2474126419847635.

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Purpose:We report a case of a 72-year-old man with bleb-related endophthalmitis (BRE) whose vitreous samples were directly analyzed with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to rapidly identify the causative organism, whereas the results from conventional microbiological techniques were negative.Methods:We analyzed BRE vitreous samples with MALDI-TOF MS (Vitek MS, bioMérieux) for rapid pathogen identification without prior culture. Samples were also analyzed with standard microbiological methods.Results:Within 1 hour of sample acquisition, MALDI-TOF MS identified Gemella sanguinis from the undiluted vitreous sample from vitrectomy without prior culture with a confidence value of 99.7%. Gram stain and cultures from aqueous and vitreous samples were negative for 28 days after acquisition. The patient’s right-eye vision improved from hand motion to 20/50 2 months later.Conclusions:Our findings suggest that the direct analysis of intraocular samples with MALDI-TOF MS could be a novel, promising adjuvant method of rapid endophthalmitis diagnosis.

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Rodríguez-Sánchez, Belén, María Jesús Ruiz-Serrano, Mercedes Marín, Paula López Roa, Marta Rodríguez-Créixems, and Emilio Bouza. "Evaluation of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identification of Nontuberculous Mycobacteria from Clinical Isolates." Journal of Clinical Microbiology 53, no. 8 (June 10, 2015): 2737–40. http://dx.doi.org/10.1128/jcm.01380-15.

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Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) for the identification of nontuberculous mycobacterial (NTM) isolates was evaluated in this study. Overall, 125 NTM isolates were analyzed by MALDI-TOF and GenoType CM/AS. Identification by 16S rRNA/hsp65sequencing was considered the gold standard. Agreements between MALDI-TOF and GenoType CM/AS with the reference method were, respectively, 94.4% and 84.0%. In 17 cases (13.6%), results provided by GenoType and MALDI-TOF were discordant; however, the reference method agreed with MALDI-TOF in 16/17 cases (94.1%;P= 0.002).

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Murray, David L., John R. Mills, Maria Alice V. Willrich, David Barnidge, Mindy C. Kohlhagen, and Angela Dispenzieri. "A Rapid MALDI-TOF Method for Isotyping and Quantitating M-Proteins in a Single Assay: Longitudinal Comparison to Serum Protein Electrophoresis and Hevylite for Monitoring Patients with Monoclonal Gammopathies." Blood 126, no. 23 (December 3, 2015): 1780. http://dx.doi.org/10.1182/blood.v126.23.1780.1780.

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Abstract Background: Current laboratory methods for detection of monoclonal gammopathies include a panel of serum protein electrophoresis (SPEP), immunofixation electrophoresis (IFE) and serum free light chain quantitation (FLC). Our group has recently described a new assay based on matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry (MS) which is capable of detecting, isotyping and quantitating M-proteins in a single assay. The basic principle of the method involves leveraging the unique mass resulting from light chain (LC) Ig gene rearrangement in B-cells. In a similar fashion to SPEP, the mass distribution of LCs after dissociation from their heavy chains can be examined for the presence of an over expressed light chain. In this study we retrospectively compared the MALDI-TOF MS method to SPEP, IFE and Hevylite ratios for monitoring patients with monoclonal gammopathies. Methods: Serum from patients who had at least 1 diagnostic and 4 serial follow-up samples was enriched for IgG, IgA, IgM, kappa and lambda using nanobodies. After disassociating the heavy and light chains by reduction, the five purified samples were spotted onto a Bruker Microflex MALDI plate. Automated acquisition (~10 seconds/sample) was performed and the five LC mass spectra from each enrichment were overlaid. M-proteins were detected, quantitated and isotyped by the presence of distinct peaks (m-spike) within LC mass to charge regions. The serial patient samples were then measured by MALDI-TOF and a comparison of results was made to previous aquired data. The results were then analyze in light of clinical and lab data in order to evaluate the ability of the MALDI-TOF MS method to monitor patients with monoclonal gammopathies. Results: In M-protein positive patient samples, serial dilution revealed MALDI-TOF MS to have ~10-times lower limit of detection than IFE. M-protein isotype in the cohort by MALDI-TOF MS was 100 percent concordant with the isotype from IFE. The MALDI TOF M-protein quantitation was linear over a clinically acceptable range (0.1 to 6 g/dL) and had improved linearity over SPEP at lower M-protein levels. M-proteins quantitation by MALDI-TOF MS compared well with SPEP with a slope of 1.16 (R2 -0.93). Hevylite Ig ratios for each isotype were statistically similar to those from MALDI-TOF MS demonstrating the ability of the MALDI to measure isotype suppression. For some patients, the MALDI method was able to detect M-proteins in patients with normal Hevylite ratios. Finally, the results for each patient were then compared over the course of monitoring. The time evolution change in M-protein concentration was similar among the three methods with the exception of a few samples in which the MALDI-TOF detected residual M-proteins in treated patients not detected by the other methods. Conclusion: This preliminary study demonstrates that MALDI-TOF MS method can provide detection, quantitation and isotyping data suitable for monitoring patients. This is a significant finding since the MALDI-TOF method is amendable to automation, is rapid and in its current format is cost-competitive with current clinical assays. Disclosures Murray: Mayo Clinic: Patents & Royalties: Patent Application Filed. Mills:Mayo Clinci: Patents & Royalties: Patent Application Filed. Barnidge:Mayo Clinic: Patents & Royalties: Patent Application Filed.

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Hazen, Tracy H., Robert J. Martinez, Yanfeng Chen, Patricia C. Lafon, Nancy M. Garrett, Michele B. Parsons, Cheryl A. Bopp, M. Cameron Sullards, and Patricia A. Sobecky. "Rapid Identification of Vibrio parahaemolyticus by Whole-Cell Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry." Applied and Environmental Microbiology 75, no. 21 (September 11, 2009): 6745–56. http://dx.doi.org/10.1128/aem.01171-09.

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ABSTRACT Vibrio parahaemolyticus is a pathogenic marine bacterium that is the main causative agent of bacterial seafood-borne gastroenteritis in the United States. An increase in the frequency of V. parahaemolyticus-related infections during the last decade has been attributed to the emergence of an O3:K6 pandemic clone in 1995. The diversity of the O3:K6 pandemic clone and its serovariants has been examined using multiple molecular techniques including multilocus sequence analysis, pulsed-field gel electrophoresis, and group-specific PCR analysis. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has become a powerful tool for rapidly distinguishing between related bacterial species. In the current study, we demonstrate the development of a whole-cell MALDI-TOF MS method for the distinction of V. parahaemolyticus from other Vibrio spp. We identified 30 peaks that were present only in the spectra of the V. parahaemolyticus strains examined in this study that may be developed as MALDI-TOF MS biomarkers for identification of V. parahaemolyticus. We detected variation in the MALDI-TOF spectra of V. parahaemolyticus strains isolated from different geographical locations and at different times. The MALDI-TOF MS spectra of the V. parahaemolyticus strains examined were distinct from those of the other Vibrio species examined including the closely related V. alginolyticus, V. harveyi, and V. campbellii. The results of this study demonstrate the first use of whole-cell MALDI-TOF MS analysis for the rapid identification of V. parahaemolyticus.

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Furukawa, Yuko, Mitsuru Katase, and Kazunobu Tsumura. "Evaluation of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry for Rapid Identification of Bacteria in Processed Soybean Products." Journal of Food Research 2, no. 3 (May 16, 2013): 104. http://dx.doi.org/10.5539/jfr.v2n3p104.

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Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has recently been demonstrated as a rapid and reliable method for identifying bacteria in colonies grown on culture plates. Rapid identification of food spoilage bacteria is important for ensuring the quality and safety of food. To shorten the time of analysis, several researchers have proposed the direct MALDI-TOF MS tequnics for identification of bacteria in clinical samples such as urine and positive blood cultures. In this study, processed soybean products (total 26 test samples) were initially conducted a culture enrichiment step and bacterial cells were separated from interfering components. Harvested bacterial cells were determined by MALDI-TOF MS and 16S rRNA gene sequencing method. Six processed soybean products (23%) were increased bacterial cells after culture enrichiment step and they were sucessfully obtained the accurate identification results by MALDI-TOF MS-based method without colony formation.

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Kim, Jeong-Han, Taek Soo Kim, Hyun gul Jung, Chang Kyung Kang, Kang-Il Jun, Sangkwon Han, Dong Young Kim, et al. "Prospective evaluation of a rapid antimicrobial susceptibility test (QMAC-dRAST) for selecting optimal targeted antibiotics in positive blood culture." Journal of Antimicrobial Chemotherapy 74, no. 8 (April 30, 2019): 2255–60. http://dx.doi.org/10.1093/jac/dkz168.

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Abstract Objectives MALDI-TOF MS has been successfully used for empirical antibiotic selection. However, limited data are available regarding the usefulness of MALDI-TOF MS in common resistant organisms compared with rapid antimicrobial susceptibility testing (AST). We prospectively evaluated the usefulness of rapid AST, compared with MALDI-TOF MS, for optimal antibiotic selection by infectious disease (ID) physicians in patients with bacteraemia including polymicrobial infection. Methods Three hundred and fifty-nine patients with positive blood culture were included for analysis. ID physicians prospectively decided on antibiotic regimens with consensus at each timepoint of receiving results of Gram stain, MALDI-TOF MS and rapid AST, the last of which was performed using QMAC-dRAST. Results ID physicians with MALDI-TOF MS results chose optimal targeted antibiotics in 255 (71.0%) cases, with appropriate antibiotic selection in 303 (84.4%) cases. The proportion of optimal targeted antibiotic selection and appropriate antibiotic selection was significantly lower for resistant strains than for susceptible strains [62.5% versus 79.2% (P < 0.001) and 68.2% versus 100% (P < 0.001), respectively]. QMAC-dRAST results led to optimal antibiotic treatment in 95 (91.3%) of the 104 cases receiving non-optimal targeted antibiotics. Optimal targeted treatments based on QMAC-dRAST results were possible in 322 (98.2%) of the 328 cases with monobacterial infection and in 345 (96.1%) of the 359 cases with monobacterial and polymicrobial infection. Conclusions MALDI-TOF MS has a high chance of failure in guiding ID physicians to optimal antibiotics, especially against resistant organisms. With increasingly common resistant organisms, rapid AST is needed to identify optimal targeted antibiotics early in bacteraemia.

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Sevestre, Jacques, Mohamed Aly Ould Lemrabott, Jean-Michel Bérenger, Adama Zan Diarra, Ali Ould Mohamed Salem Boukhary, and Philippe Parola. "Detection of Arthropod-Borne Bacteria and Assessment of MALDI-TOF MS for the Identification of Field-Collected Immature Bed Bugs from Mauritania." Insects 14, no. 1 (January 11, 2023): 69. http://dx.doi.org/10.3390/insects14010069.

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Human infestations by bed bugs have upsurged globally in recent decades, including in African countries, where recent reports pointed out an increase in infestation. Sympatric dwelling has been described for two species of bed bug parasitizing humans: Cimex hemipterus (the tropical bed bug) and C. lectularius. Identification of these two species is based on morphological characteristics, and gene sequencing, and may also rely on Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS). The present work aimed to assess whether MALDI-TOF MS was applicable for species level identification of immature stages of Cimex. Arthropods were collected in domestic settings in Nouakchott, Mauritania. Identification used morphological keys and MALDI-TOF MS identification was assessed for immature stages. Quantitative PCR and sequencing assays were used to detect arthropod-associated bacteria in each specimen. A total of 92 arthropods were collected, all morphologically identified as C. hemipterus (32 males, 14 females and 45 immature stages). A total of 35/45 specimens produced good quality MALDI-TOF MS spectra. Analysis allowed species level identification of all immature C. hemipterus after their spectra were entered into our in-house MALDI-TOF MS arthropod spectra database. Molecular screening allowed detection of Wolbachia DNA in each specimen. These results suggested that MALDI-TOF MS is a reliable tool for species level identification of Cimex specimens, including immature specimens. Future studies should assess this approach on larger panels of immature specimens for different Cimex species and focus on the precise staging of their different immature developmental stages.

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Rindi, Laura, Vincenzo Puglisi, Iacopo Franconi, Roberta Fais, and Antonella Lupetti. "Rapid and Accurate Identification of Nontuberculous Mycobacteria Directly from Positive Primary MGIT Cultures by MALDI-TOF MS." Microorganisms 10, no. 7 (July 18, 2022): 1447. http://dx.doi.org/10.3390/microorganisms10071447.

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Over the last years, nontuberculous mycobacteria (NTM) have emerged as important human pathogens. Accurate and rapid mycobacterial species identification is needed to successfully diagnose, treat, and manage infections caused by NTM. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry, MALDI-TOF MS, was demonstrated to effectively identify mycobacteria isolates subcultured from solid or liquid media rather than new positive cultures. The present study aims to develop a new extraction protocol to yield rapid and accurate identification of NTM from primary MGIT cultures by MALDI-TOF MS. A total of 60 positive MGIT broths were examined by the Bruker Biotyper system with Mycobacteria Library v. 2.0 (Bruker Daltonics GmbH & Co. KG., Bremen, Germany). The results were compared with those obtained by the molecular method, line probe assay GenoType Mycobacterium CM/AS/NTM-DR. All samples were concordantly identified by MALDI-TOF MS and the molecular test for all the tested mycobacteria. Fifty-seven (95%) MGIT positive cultures for NTM from clinical samples had a MALDI-TOF MS analysis score S ≥ 1.8. Although a small number of strains and a limited diversity of mycobacterial species were analysed, our results suggest that MALDI-TOF MS could represent a promising routine diagnostic tool for identifying mycobacterial species directly from primary liquid culture.

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Sala-Comorera, Laura, Anicet R. Blanch, Carles Vilaró, Belén Galofré, and Cristina García-Aljaro. "Heterotrophic monitoring at a drinking water treatment plant by matrix-assisted laser desorption/ionization–time of flight (MALDI-TOF) mass spectrometry after different drinking water treatments." Journal of Water and Health 15, no. 6 (October 10, 2017): 885–97. http://dx.doi.org/10.2166/wh.2017.090.

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Abstract The aim of this work was to assess the suitability of matrix-assisted laser desorption/ionization–time of flight mass spectrometry (MALDI-TOF MS) for routine heterotrophic monitoring in a drinking water treatment plant. Water samples were collected from raw surface water and after different treatments during two campaigns over a 1-year period. Heterotrophic bacteria were studied and isolates were identified by MALDI-TOF MS. Moreover, the diversity index and the coefficient of population similarity were also calculated using biochemical fingerprinting of the populations studied. MALDI-TOF MS enabled us to characterize and detect changes in the bacterial community composition throughout the water treatment plant. Raw water showed a large and diverse population which was slightly modified after initial treatment steps (sand filtration and ultrafiltration). Reverse osmosis had a significant impact on the microbial diversity, while the final chlorination step produced a shift in the composition of the bacterial community. Although MALDI-TOF MS could not identify all the isolates since the available MALDI-TOF MS database does not cover all the bacterial diversity in water, this technique could be used to monitor bacterial changes in drinking water treatment plants by creating a specific protein profile database for tracking purposes.

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Huber, Charlotte A., Sarah J. Reed, and David L. Paterson. "Bacterial Sub-Species Typing Using Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry: What Is Promising?" Current Issues in Molecular Biology 43, no. 2 (July 20, 2021): 749–57. http://dx.doi.org/10.3390/cimb43020054.

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Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is routinely used for bacterial identification. It would be highly beneficial to also be able to use the technology as a fast way to detect clinically relevant clones of bacterial species. However, studies to this aim have often had limited success. The methods used for data acquisition, processing and data interpretation are highly diverse amongst studies on MALDI-TOF MS sub-species typing. In addition to this, feasibility may depend on the bacterial species and strains investigated, making it difficult to determine what methods may or may not work. In our paper, we have reviewed recent research on MALDI-TOF MS typing of bacterial strains. Although we found a lot of variation amongst the methods used, there were approaches shared by multiple research groups. Multiple spectra of the same isolate were often combined before further analysis for strain distinction. Many groups used a protein extraction step to increase resolution in their MALDI-TOF MS results. Peaks at a high mass range were often excluded for data interpretation. Three groups have found ways to determine feasibility of MALDI-TOF MS typing for their set of strains at an early stage of their project.

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Journal articles on the topic 'MALDI-TOF MS'

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