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A novel short-term high-lactose culture approach combined with a matrix-assisted laser desorption ionization-time of flight mass spectrometry assay for differentiating Escherichia coli and Shigella species using artificial neural networks
摘要： Background Escherichia coli is currently unable to be reliably differentiated from Shigella species by routine matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. In the present study, a reliable and rapid identification method was established for Escherichia coli and Shigella species based on a short-term high-lactose culture using MALDI-TOF MS and artificial neural networks (ANN). Materials and methods The Escherichia coli and Shigella species colonies, treated with (Condition 1)/without (Condition 2) a short-term culture with an in-house developed high-lactose fluid medium, were prepared for MALDI-TOF MS assays. The MS spectra were acquired in linear positive mode, with a mass range from 2000 to 12000 Da and were then compared to discover new biomarkers for identification. Finally, MS spectra data sets 1 and 2, extracted from the two conditions, were used for ANN training to investigate the benefit on bacterial classification produced by the new biomarkers. Results Twenty-seven characteristic MS peaks from the Escherichia coli and Shigella species were summarized. Seven unreported MS peaks, with m/z 2330.745, m/z 2341.299, m/z 2371.581, m/z 2401.038, m/z 3794.851, m/z 3824.839 and m/z 3852.548, were discovered in only the spectra from the E. coli strains after a short-term high-lactose culture and were identified as belonging to acid shock protein. The prediction accuracies of the ANN models, based on data set 1 and 2, were 97.71±0.16% and 74.39±0.34% (n = 5), with an extremely remarkable difference (p < 0.001), and the areas under the curve of the receiver operating characteristic curve were 0.72 and 0.99, respectively. Conclusions In summary, adding a short-term high-lactose culture approach before the analysis enabled a reliable and easy differentiation of Escherichia coli from the Shigella species using MALDI-TOF MS and ANN.
关键词： MALDI-TOF MS,Escherichia coli,high-lactose culture,artificial neural networks,Shigella species
更新于2025-09-16 10:30:52
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Rapid pathogen identification and antimicrobial susceptibility testing in in vitro endophthalmitis with matrix assisted laser desorption-ionization Time-of-Flight Mass Spectrometry and VITEK 2 without prior culture
摘要： Prompt clinical diagnosis and initiation of treatment are critical in the management of infectious endophthalmitis. Current methods used to identify causative agents of infectious endophthalmitis are mostly inefficient, owing to suboptimal sensitivity, length, and cost. Matrix Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) can be used to rapidly identity pathogens without a need for culture. Similarly, automated antimicrobial susceptibility test systems (AST, VITEK 2) provide accurate antimicrobial susceptibility profiles. In this proof-of-concept study, we apply these technologies for the direct identification and characterization of pathogens in vitreous samples, without culture, as an in vitro model of infectious endophthalmitis.
关键词： endophthalmitis,pathogen identification,MALDI-TOF MS,antimicrobial susceptibility testing,VITEK 2
更新于2025-09-12 10:27:22
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Chemical derivatization coupled with matrix assisted laser desorption ionization time-of-flight mass spectrometry for convenient and efficient <i>N</i> -glycan detection in human plasma
摘要： As one of the most common post-translational modifications, protein N-glycosylation is involved in most important biological processes. Structural changes of the protein linked N-glycans have close correlations with the occurrence and progression of various diseases. Therefore, efficient detection of these disease-associated aberrations is of great significance for the development of new diagnostic biomarkers and therapeutic drug targets. In this work, we developed a method for convenient and effective N-glycan detection by coupling condition controlled chemical derivatization with MALDI-TOF MS. Due to the high reaction efficiency and enhanced hydrophobicity, improved identification scales were obtained for N-glycans from both asialofetuin and human plasma compared with the direct analysis.
关键词： asialofetuin,MALDI-TOF MS,N-glycan,human plasma,chemical derivatization
更新于2025-09-12 10:27:22
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Detection of Hb Phnom Penh by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry during the measurement of glycated hemoglobin
摘要： Hemoglobin (Hb) variant is a well-known cause of erroneous results of glycated hemoglobin (HbA1c). During routine clinical HbA1c analysis with Variant II Turbo 2.0 (VII-T 2.0; Bio-Rad, USA), we encountered seven patients over a 3-year period who showed no HbA2 peak in chromatograms, but a roughly normal Hb pattern. In addition, a marked discordance was observed between the results of HbA1c and fasting plasma glucose. In this study, we performed further investigation on the seven samples. Subsequent Hb analysis by a capillary electrophoresis (CE) method (CAPILLARYS 2, Hb program; Sebia, France) and a cation exchange high-performance liquid chromatography (HPLC) method (Variant II, β-thalassemia short program) showed no signs of abnormal peaks in samples 1–7. Further HbA1c analysis was conducted by a boronate affinity HPLC system (Premier Ultra2; Trinity Biotech, Ireland) CAPILLARYS 2, and a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) system (QuanTOF; Intelligene Biosystems, China) respectively. All operations were conducted according to the manufacturers’ instructions. For QuanTOF, HbA1c was measured following the protocol described in our previous study.
关键词： MALDI-TOF MS,HbA1c,hemoglobin variants
更新于2025-09-12 10:27:22
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Discrimination of <i>Aspergillus flavus</i> from <i>Aspergillus oryzae</i> by matrix‐assisted laser desorption/ionisation time‐of‐flight (MALDI‐TOF) mass spectrometry
摘要： Background: Aspergillus flavus is a major cause of severe non‐invasive fungal infections in the Middle Eastern countries. However, it is difficult to distinguish A flavus from A oryzae. Objectives: To assess the potential of matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOF MS) in discriminating between A flavus and A oryzae and compare it with β‐tubulin gene sequencing. Methods: We used the Bruker Daltonik MALDI‐TOF MS system to analyse 200 clinical and environmental A flavus isolates and one A pseudonomius and one A alliaceus (Aspergillus section Flavi) isolate a priori identified as such by sequencing of the β‐tubulin gene. Results: All 200 A flavus isolates were identified at the genus level and 176 (88%) at the species levels by MALDI‐TOF MS based on the spectral log‐scores (≥2.0 and 1.7‐1.99, respectively); among them, only 18 (10.2%) were confirmed as A flavus, whereas 35 (19.9%) were identified as A oryzae and 123 (69.9%) as A flavus/A oryzae. Aspergillus pseudonomius and A alliaceus were misidentified as A flavus and A parasiticus with log‐score values of 1.39 and 1.09, respectively. Conclusions: The results indicate that the commercially available Bruker Daltonik MALDI‐TOF MS score database cannot separate A flavus and A oryzae species. We also showed that establishment of an in‐house library is a useful tool to discriminate closely related Aspergillus species, including A flavus and A oryzae.
关键词： identification,MALDI‐TOF MS,β‐tubulin,Aspergillus oryzae,Aspergillus flavus
更新于2025-09-11 14:15:04
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Evaluation of Staphylococcus aureus Subtyping Module for Methicillin-Resistant Staphylococcus aureus Detection Based on Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry
摘要： A recent developed S. aureus subtyping module for rapidly differentiate methicillin-resistant Staphylococcus aureus (MRSA) from methicillin-susceptible S. aureus (MSSA) had been introduced into China. The principle of this method was to identify the methicillin resistance through detection of a specific phenol soluble modulin-mec peak (PSM-mec) by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). A total of 347 non-duplicated S. aureus strains were collected from the Second Affiliated Hospital of Zhejiang University School of Medicine during January 2014 to February 2019. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the automated subtyping module in identifying MRSA were evaluated. The specificity and PPV of this method were both 100% and the sensitivity was 60.2%. PSM-bearing MRSA were reported with different prevalence from different parts of world, our sample collection has the highest percentage so far. The repeatability showed that 1.7% (6/347) and 18.4% (64/347) were reported differently in the intra- and inter- batch analysis, respectively, which demonstrated that the threshold of this method could be further optimized to increase the sensitivity of MRSA detection. Overall, Bruker? MALDI Biotyper can detect S. aureus isolates with a quite high specificity and expedite the identification of MRSA isolates without using extra reagent, labor or time. The reduced turnaround time of MRSA identification is essential for appropriate therapeutic management and timely intervention for infection control.
关键词： MRSA,MALDI-TOF MS,resistant,specificity,sensitivity
更新于2025-09-11 14:15:04
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Matrix-assisted laser desorption/ionization time of flight mass spectrometry identification of Vibrio (Listonella) anguillarum isolated from sea bass and sea bream
摘要： Vibrio (Listonella) anguillarum is a pathogenic bacterium causing septicaemia in a wide range of marine organisms and inducing severe mortalities, thus it is crucial to conduct its accurate and rapid identification. The aim of this study was to assess MALDI-TOF MS as a method of choice for identification of clinical V. anguillarum isolates from affected marine fish. Since the method accuracy might be influenced by the type of the medium used, as well as by the incubation conditions, we tested V. anguillarum isolates grown on standard media with and without the addition of NaCl, cultured at three incubation temperatures, and at three incubation periods. The best scores were retrieved for V. anguillarum strains grown on NaCl-supplemented tryptone soy agar (TSA) at 22?C and incubated for 48h (100% identification to species level; overall score 2.232), followed by incubation at 37?C and 48h (100% to species level; score 2.192). The strains grown on non-supplemented TSA gave the best readings when incubated at 22?C for 72h (100% identification to species level; overall score 2.182), followed by incubation at 15?C for 72h (100% to species level; score 2.160). Unreliable identifications and no-identifications were growing with the incubation duration at 37?C, on both media, amounting to 88.89% for 7d incubation on supplemented TSA, and 92.60% for 7d incubation on non-supplemented TSA. The age of the cultured strains and use of media significantly impacted the mass spectra, demonstrating that for reliable identification, MALDI-TOF MS protein fingerprinting with the on-target extraction should be performed on strains grown on a NaCl-supplemented medium at temperatures between 15 and 22?C, incubated for 48–72 hours.
关键词： culture conditions,marine fish,MALDI-TOF MS,identification,Vibrio anguillarum
更新于2025-09-11 14:15:04
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Factors contributing to degradation of organic photovoltaic cells
摘要： The performance of organic photovoltaic (OPV) cells has considerably improved over the past decade, and now exceeds an energy conversion efficiency of 10%, the benchmark for practical use. One factor contributing to this increase is the development of π-conjugated linear acceptor molecules as alternatives to fullerene derivatives. Although conversion efficiency is an important issue for practical applications, device stability is also necessary for commercialization of OPV technologies. To date, long-term stability has been examined in OPV devices based on fullerenes. However, the factors involved in performance degradation remain poorly understood. It is difficult to address this problem because of the multilayer nature of the devices and many factors involved in degradation. In recent OPV devices based on π-conjugated molecules as acceptors, there have been few reports on stability under continuous light irradiation. Ensuring the stability of the π-conjugated molecules under illumination and electrical operation is critical for achieving practical use of OPV devices. In this paper, we comprehensively analyzed OPV devices based on EH-IDTBR as an acceptor material. We identified a decrease in OPV performance of approximately 50% under 100-hour light irradiation, which we attribute to increased resistance of the organic semiconductor layer. The increase in resistance was caused by a decrease in the number of carriers, suggesting that structural changes in the EH-IDTBR molecule are an important factor affecting degradation.
关键词： Durability,impedance measurement,organic photovoltaic,stability,MALDI-TOF-MS
更新于2025-09-11 14:15:04
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Plasmonic Colloidosome-Based Multifunctional Platform for Bacterial Identification and Antimicrobial Resistance Detection
摘要： Antimicrobial resistance (AMR) is an urgent threat to public health. Rapid bacterial identification and AMR tests are important to promote personalized treatment of patients and to limit the spread of AMR. Herein, we explore the utility of plasmonic colloidosomes in bacterial analysis based on mass spectrometry (MS) and Raman scattering. It is found that colloidosomes can provide a rigid micron-size platform for bacterial culture and analysis. Coupled with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS, this platform enables bacterial identification at the species level with cell counts as low as 50, > 100 times more sensitive than the standard method of MALDI-TOF MS based bacterial identification. Coupled with Raman scattering, it can distinguish single bacterial cells at the strain level and recognize AMR at the single-cell level. These reveal the broad potential of the platform for flexible and versatile bacterial detection and typing.
关键词： Plasmonic colloidosomes,MALDI-TOF MS,Raman scattering,antimicrobial resistance detection,bacterial identification
更新于2025-09-11 14:15:04
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Matrix-Assisted Laser Desorption/Ionization Time-of-Flight
摘要： Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has undoubtedly changed the way clinical microbiology laboratories (CMLs) diagnose infectious diseases. Now commonly used for the routine identification of cultured bacteria and yeast, CMLs are looking to expand the use of MALDI-TOF MS to other areas of infectious diseases diagnostics. The relative ease of performance, low cost per test, and rapidity of results has prompted the development of advanced techniques, such as antimicrobial susceptibility, direct-from-specimen organism identification, and several other techniques that may improve on conventional techniques.
关键词： MALDI-TOF MS,Phenotypic susceptibility testing,Rapid organism identification,Infectious diseases diagnostics
更新于2025-09-11 14:15:04