Use Of Matrix-assisted Laser Desorption/ionization Time-of-flight Mass Spectrometry Research Articles

Recent Advances and Potential Future Applications of MALDI-TOF Mass Spectrometry for Identification of Helminths.

Helminth infections caused by nematodes, trematodes, and cestodes are major neglected tropical diseases and of great medical and veterinary relevance. At present, diagnosis of helminthic diseases is mainly based on microscopic observation of different parasite stages, but microscopy is associated with limited diagnostic accuracy. Against this background, recent studies described matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry as a potential, innovative tool for helminth identification and differentiation. MALDI-TOF mass spectrometry is based on the analysis of spectra profiles generated from protein extracts of a given pathogen. It requires an available spectra database containing reference spectra, also called main spectra profiles (MSPs), which are generated from well characterized specimens. At present, however, there are no commercially available databases for helminth identification using this approach. In this narrative review, we summarize recent developments and published studies between January 2019 and September 2022 that report on the use of MALDI-TOF mass spectrometry for helminths. Current challenges and future research needs are identified and briefly discussed.

The Use of MALDI-TOF MS as a Diagnostic Tool for Adult Trichuris Species.

Trichuriasis is considered a neglected tropical disease, being the second most common helminthiasis in humans. Detection of Trichuris in routine diagnosis is usually done by microscopic detection of eggs in fecal samples. Other molecular analyses are more reliable and could be used, but these analyses are not routinely available in clinical microbiology laboratories. The use of matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is increasing since the last decades due to its recent evidence as a potential role for reliable identification of microorganisms and a few nematodes. But, for parasites detection, normalized protocols and the acquisition and introduction of new species to the database are required. We carried out a preliminary study confirming the usefulness of MALDI-TOF MS for the rapid and reliable identification of Trichuris suis used as control and the creation of an internal database. To create main spectra profiles (MSPs), the different parts of five whipworms (esophagus and intestine) were used, developing different tests to verify the repeatability and reproducibility of the spectra. Thus, to validate the new internal database, 20 whipworms, separating the esophagus and intestine, were used, of which 100% were accurately identified as T. suis, but could not distinguish between both parts of the worm. Log score values ranged between 1.84 and 2.36, meaning a high-quality identification. The results confirmed that MALDI-TOF MS was able to identify Trichuris species. Additionally, a MALDI-TOF MS profile of T. suis proteome was carried out to develop the first internal database of spectra for the diagnosis of trichuriasis and other Trichuris spp.

Use of MALDI-ToF Mass Spectrometry for Identification of Leptospira.

Medical microbiology has used phenotypical and metabolic criteria to identify bacterial pathogens for decades. However, no such criteria have been applied to identify leptospires at the species level. In the recent years, matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry (MS) has emerged as new tool for the identification of bacterial species in the medical microbiology laboratory. This technology has rapidly gained more and more popularity. Actually, this technique is sensitive and economic, saving both labor and bench costs, but also rapid, significantly reducing turnaround time from isolation to identification. MALDI-ToF MS provides an unprecedented tool for the rapid identification of Leptospira at the species level.

Impact of matrix-assisted laser desorption/ionization time of flight mass spectrometric evaluation on the clinical outcomes of patients with bacteremia and fungemia in clinical settings lacking an antimicrobial stewardship program: a pre-post quasi experimental study

BackgroundsSeveral studies have evaluated the impact of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) combined with antimicrobial stewardship in patients with positive blood cultures; clinical outcomes improved. However, in many hospitals, antimicrobial stewardship is not available because of restricted medical resources. Thus, we investigated the impact of evaluation by MALDI-TOF MS on the clinical outcomes of patients with bacteremia and fungemia treated in a clinical setting lacking an antimicrobial stewardship program (ASP).MethodsWe designed a pre–post quasi experimental study and retrospectively reviewed the medical records of patients aged > 18 years old with bacteremia and fungemia during two periods: October–December 2012 and October–December 2013. Conventional methods were used to detect microbial pathogens in 2012, and MALDI-TOF MS was employed in 2013. Clinical outcomes compared between periods were the time to pathogen identification, time to effective therapy, 30-day all-cause mortality, time to microbiological clearance, length of ICU stay, and rate of recurrence of the same bloodstream infection (BSI).ResultsA total of 556 patients were enrolled; 302 patients in 2012, and 254 in 2013. The use of MALDI-TOF MS without an ASP reduced the time to pathogen identification (86.4 vs. 63.5 h, P < 0.001) but did not significantly reduce the time to effective therapy (27.4 vs. 23.2 h, P = 0.187). Also, none of the following differed significantly between the two periods: mortality (17.5 vs. 15.7%, P = 0.571), the time to microbiological clearance (3.6 vs. 3.7 days, P = 0.675), the length of ICU stay (16.8 vs. 14.7 days, P = 0.706), and the recurrence rate of the same BSI (5.0 vs. 2.8%, P = 0.183).ConclusionsThe use of MALDI-TOF MS alone in a setting lacking an ASP did not afford clinical benefits. An ASP combined with MALDI-TOF MS is necessary to improve clinical outcomes.

Use of MALDI-TOF MS to Discriminate between Biofilm-Producer and Non-Producer Strains of Staphylococcus epidermidis.

For the management of Staphylococci coagulase-negative infection, often related to biofilm formation, rapid and accurate identification is necessary in choosing a correct antibiotic therapy. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) is becoming increasingly important for bacterial identification over traditional methods. Our aim was to validate the use of MALDI to discriminate Staphylococcus epidermidis biofilm-producing strains. Clinical strains coming from suture wires were identified and their protein profiles were compared to that obtained from two ATCC reference strains (biofilm producer and non-producer). MALDI identified the eighteen isolates as S. epidermidis, combining sixteen profiles with the biofilm producer and two with the non-producer, confirming the results of crystal violet assay. Our data highlight that MALDI can be considered a good tool to discriminate between biofilm-producer and non-producer strains of S. epidermidis, thus helping to establish an effective antibiotic therapy.

Aplicación de la espectrometría de masas en micología

MALDI-TOF (matrix-assisted laser desorption ionization time-of-flight) mass spectrometry (MS) is becoming an essential tool in most microbiology laboratories. At present, by using a characteristic fungal profile obtained from whole cells or through simple extraction protocols, MALDI-TOF MS allows the identification of pathogenic fungi with a high performance potential. This methodology decreases the laboratory turnaround time, optimizing the detection of mycoses. This article describes the state-of-the-art of the use of MALDI-TOF MS for the detection of human clinical fungal pathogens in the laboratory and discusses the future applications of this technology, which will further improve routine mycological diagnosis.

Aplicación de la espectrometría de masas en la identificación de bacterias

Correct and rapid identification of bacteria is essential for the correct diagnosis and treatment of infected patients. Until a few years ago, biochemical, colorimetric or even antibiotic sensitivity tests were used to identify genera and species. The main limitations of these methods were the time needed for their performance and the difficulty of distinguishing between microorganisms that were little reactive, highly similar, or difficult to culture. Many of these problems have been solved by the introduction of mass spectrometry (MS) in the laboratory with the use of MALDI-TOF (matrix-assisted laser desorption ionization time-of-flight). Knowledge of the strengths and weaknesses of this technology is essential to be able to take maximum advantage of this technique. Not all microorganisms can be identified with the same ease and reliability by MALDI-TOF and microbiologists need to know how to interpret the results obtained with this technique and the available alternatives in order to identify the microorganisms causing the most problems. This article aims to summarise the available information on the correct identification of the main human pathogenic bacteria through the use of MALDI-TOF MS, focusing on Gram-negative, Grampositive and anaerobic microorganisms. The main factors that must be taken into account for the reliable identification of any bacterium are the conditions for culture, sample preparation with the ideal extraction method and especially the use of a correct and updated database.

Applications of MALDI-TOF MS in environmental microbiology.

Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) is an emerging technique for microbial identification, characterization, and typing. The single colony method can be used for obtaining a protein fingerprint or profile unique to each microorganism. This technique has been mainly used in the clinical field, but it also has significant potential in the environmental field. The applications of MALDI-TOF MS in environmental microbiology are discussed in this review. An overview on the use of MALDI-TOF MS for environmental proteomics and metabolomics is given as well as its use for bacterial strain typing and bioremediation research. A more detailed review on the use of this technique for the identification, differentiation, and categorization of environmental microorganisms is given. Some of the parameters that can influence the results and reproducibility of MALDI-TOF MS are also discussed.

MALDI-TOF mass spectrometry: any use for Aspergilli?

Recently, relentless efforts to develop rapid, cost-effective, and reliable laboratory methods for daily diagnosis of fungal diseases such as aspergillosis appear to be materialized in the relatively new, but revolutionary matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry (MS) technology. As for Aspergilli, MALDI-TOF MS profiling of isolates growing in culture--characteristic protein spectra are obtainable by means of simple and reproducible preanalytical and analytical procedures--ensures that single species within the different sections or complexes can be easily and accurately identified, including species that are morphologically and phylogenetically similar to each other. Thus, resort to longer and more onerous molecular biology techniques is restricted to those cases for which no spectra in the reference fungal database or library are available at the time of analysis. However, it is necessary to interrogate reference libraries composed of spectra that have been obtained using procedures similar to those used to obtain the test isolate's mass spectrum, as well as to continuously update these libraries for enriching them with fungal strains/species not (or not well) represented in their current versions. Compared to mold identification, very limited work was reported on the use of MALDI-TOF MS to perform strain typing or antifungal susceptibility testing for Aspergilli. If these complementing areas will be potentiated in the near future, MALDI-TOF MS could effectively support the clinical microbiology/mycology laboratory in its primary role of assisting either infection control specialists or physicians for the diagnosis and treatment of aspergillosis.

Kerstersia gyiorum Isolated from a Bronchoalveolar Lavage in a Patient with a Chronic Tracheostomy.

The use of the matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) generates rapid microbial identification. We are presenting a case of a 63-year-old woman with a medical history of chronic tracheostomy admitted for hypotension and fevers to illustrate the clinical implication of MALDI-TOF MS on bacterial identification. Kerstersia gyiorum was identified from the bronchoalveolar lavage isolate. Kerstersia gyiorum has been isolated from human sputum samples, and may be a previously unrecognized colonizer of the upper respiratory tract. Thus, patients with long-term tracheotomies or who are chronically aspirating may be at risk of lower respiratory infection with this organism. Increased use of MALDI-TOF MS in the clinical setting may increase reporting of this atypical isolate.

Identification of catecholamines in the immune system by desorption/ionization on silicon

Desorption/ionization from porous silicon dioxide (DIOSD), in combination with a standard matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) instrument, was used for the identification of catecholamines in the human peripheral blood lymphocytes. A routine MALDI-TOF analysis does not allow for sensitive detection of low molecular mass compounds (i.e. below 400 Da) due to the pronounced background ions arising from the matrix. Therefore, we have tested DIOSD methodology for the identification of catecholamines in the immune system. Using DIOSD, catecholamines were unambiguously identified in the cell extract of peripheral blood lymphocytes at the femtomolar level. The DIOSD extends the possible use of MALDI-TOF mass spectrometry towards small molecules that were previously detected by other methods.

Use of MALDI-TOF mass spectrometry in a 51-mutation test for cystic fibrosis: Evidence that 3199del6 is a disease-causing mutation

Purpose: We developed a 51-mutation extended cystic fibrosis (CF) panel that incorporates the 25 previously recommended CFTR mutations, plus 26 additional mutations including 3199del6, which was associated with I148T.Methods: This assay utilizes an integrated matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry system.Results: CF testing was performed on over 5,000 individuals, including a 3-year-old Hispanic-American patient with a compound heterozygous G542X/3199del6 genotype. He is negative for I148T, or other mutations assessed by CFTR gene sequencing.Conclusion: These results demonstrate the successful implementation of MALDI-TOF mass spectrometry in CF clinical testing, and establish 3199del6 as a disease-causing CF mutation.

Monitoring of immune response by blood serum profiling using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) to the analysis of blood serum leads to the observation of a large variety of reproducible mass spectral peaks corresponding to blood components. In this study, the use of MALDI-TOFMS was developed as a tool for monitoring immune response to bacterial infection. Employing the MALDI-TOFMS approach, the levels of many components of blood were found to be immune response independent whereas others were found to correlate directly with the response of the immune system to two known types of bacteria (Staphylococcus aureus and Enterococcus faecalis). The methodologies reported here should be useful for the rapid monitoring of blood, especially that of the immune response mechanisms in various animal species.

Electrospray sample preparation for improved quantitation in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The goal of this work is the development of a rapid and objective matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) method for the quantitation of peptides and proteins in human plasma suitable for use in the Good Laboratory Practices (GLP) environment, where the analytical method, validation and pharmacokinetic parameters derived from concentration data will be scrutinized by global regulatory agencies. Electrospray deposition has traditionally been used to prepare thin, uniform samples for a number of techniques, including Cf-252 plasma desorption and secondary ion mass spectrometry. Here the electrospray process of sample application is used to reduce the segregation of analyte from matrix during the sample drying step. The small droplets formed during the electrospray process are found to significantly improve the homogeneity of the sample surface prepared. Experiments comparing the traditional air dried and electrosprayed methods of sample preparation show that the increase in sample homogeneity from electrosprayed samples decreases both the within-sample spot and between-sample spot variability, resulting in a decrease in percent coefficient of variation (%CV) for the recorded MALDI mass spectra. The increase in sample homogeneity permits a more objective use of MALDI-TOFMS as a quantitative analytical method and has led to the development of an assay for the determination of desamino-[8-D-arginine] vasopressin (DDAVP) using arginine vasopressin (AVP) as internal standard in human plasma. The range of quantitation observed (2.0-10 micrograms/mL) is of limited value for bioanalytical application; however, the analysis of neat standards shows lower quantitation limits are easily achieved.