scholarly journals Rapid Simultaneous Testing of Multiple Antibiotics by the MALDI-TOF MS Direct-on-Target Microdroplet Growth Assay

Diagnostics ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1803
Author(s):  
Evgeny A. Idelevich ◽  
Ilka D. Nix ◽  
Janika A. Busch ◽  
Katrin Sparbier ◽  
Oliver Drews ◽  
...  
Keyword(s):  
Growth Control ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Assay Performance ◽  
Microbiological Methods ◽  
Humidity Chamber ◽  
Growth Assay ◽  
Technical Solutions ◽  
Growth Controls ◽  
Tof Ms

Accelerating antimicrobial susceptibility testing (AST) is a priority in the development of novel microbiological methods. The MALDI-TOF MS-based direct-on-target microdroplet growth assay (DOT-MGA) has recently been described as a rapid phenotypic AST method. In this proof-of-principle study, we expanded this method to simultaneously test 24 antimicrobials. An Enterobacterales panel was designed and evaluated using 24 clinical isolates. Either one or two (only for antimicrobials with the EUCAST “I” category) breakpoint concentrations were tested. Microdroplets containing bacterial suspensions with antimicrobials and growth controls were incubated directly on the spots of a disposable MALDI target inside a humidity chamber for 6, 8 or 18 h. Broth microdilution was used as the standard method. After 6 and 8 h of incubation, the testing was valid (i.e., growth control was successfully detected) for all isolates and the overall categorical agreement was 92.0% and 92.7%, respectively. Although the overall assay performance applying short incubation times is promising, the lower performance with some antimicrobials and when using the standard incubation time of 18 h indicates the need for thorough standardization of assay conditions. While using “homebrew” utensils and provisional evaluation algorithms here, technical solutions such as dedicated incubation chambers, tools for broth removal and improved software analyses are needed.

scholarly journals The clinical relevance of pathogen Aerococcus urinae identification by MALDI-TOF mass spectrometry: a case of sepsis in 86-year-old Caucasian male

2020 ◽  
Vol 35 (2) ◽  
Author(s):  
Jari Intra ◽  
Cecilia Sarto ◽  
Giuseppe Serra ◽  
Paolo Brambilla
Keyword(s):  
Mass Spectrometry ◽  
Urinary Tract ◽  
Previous History ◽  
Blood Stream ◽  
Maldi Tof Ms ◽  
Maldi Tof Mass Spectrometry ◽  
Maldi Tof ◽  
Microbiological Methods ◽  
Aerococcus Urinae ◽  
Tof Ms

The infrequency of urinary tract and blood stream infections caused by Aerococcus urinae is most probably due to the difficulties in the identification of this bacterium using standard microbiological methods. With the introduction of more sensitive and accurate techniques in clinical microbiology, such as genetic approaches and Matrix-Assisted Laser Desorption/Ionization-Time Of Flight (MALDI-TOF) mass spectrometry (MS), the incidence of infections due to A. urinae increased. Herein, we described a case of urinary tract and bloodstream infection caused by A. urinae, which occurred in an 86-year-old Caucasian man with a previous history of prostate cancer. The identification of A. urinae was performed by MALDI-TOF MS, since this microorganism cannot be identified by biochemical reactions. In this report, we highlight the need to consider MALDI-TOF MS as technique of choice for A. urinae identification in the presence of subjects with predisposing factors, such as old age, male gender, and genitourinary tract pathologies.

Rapid Pathogen Identification With Direct Application of MALDI-TOF Mass Spectrometry on an Endophthalmitis Vitreous Sample Without Prior Culture

2019 ◽  
Vol 3 (4) ◽  
pp. 255-259 ◽  
Author(s):  
Lindsay Y. Chun ◽  
Laura Dolle Molle ◽  
Olaf Schneewind ◽  
Dominique Missiakas ◽  
Kathleen G. Beavis ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Direct Analysis ◽  
Causative Organism ◽  
Pathogen Identification ◽  
Maldi Tof Ms ◽  
Hand Motion ◽  
Maldi Tof ◽  
Microbiological Methods ◽  
Vitreous Sample ◽  
Tof Ms

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.

scholarly journals Development of a MALDI-TOF MS-based screening panel for accelerated differential detection of carbapenemases in Enterobacterales using the direct-on-target microdroplet growth assay

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Carlos L. Correa-Martínez ◽  
Evgeny A. Idelevich ◽  
Katrin Sparbier ◽  
Thorsten Kuczius ◽  
Markus Kostrzewa ◽  
...  
Keyword(s):  
Differential Detection ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Growth Assay ◽  
Tof Ms

scholarly journals Identification of Fungi Isolated from Oral Cavity of Patients with HIV Using MALDI–TOF MS

2021 ◽  
Vol 10 (8) ◽  
pp. 1570
Author(s):  
Zuzanna Pawlak ◽  
Szymon Andrusiów ◽  
Magdalena Pajączkowska ◽  
Adriana Janczura
Keyword(s):  
Fungal Infections ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Flight Mass Spectrometry ◽  
Common Mistake ◽  
Microbiological Methods ◽  
Study Results ◽  
Identification Of Fungi ◽  
Group A ◽  
Tof Ms

Background: A growing incidence of invasive fungal infections, especially among immunocompromised patients, has given increased significance to microbiological diagnostics of yeast-like fungi. More accurate and faster fungi identification methods that can compete with classical methods are being searched for. In this paper, classical microbiological methods are compared to MALDI–TOF MS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry). Methods: The diagnostic material was collected from buccal mucosa from 98 adults, including 69 with HIV. Only positive cultures were included in the study. Results: Matching results were obtained in 45 samples, and there were nonmatching results in 35 samples, with the majority of these in the study group, constituting 50% of identifications within this group. A particularly common mistake resulting from the use of classical methods is the false identification of C. dubliniensis as C. albicans. Additionally, C. tropicalis proves to be difficult to identify. Conclusions: Our results and literature data suggest that MALDI–TOF MS should be considered an effective alternative to classical methods in terms of fungi identification, especially among HIV-positive patients, due to the different morphology of fungal colonies.

Identification of Lysinibacillus fusiformis Isolated from Cosmetic Samples Using MALDI-TOF MS and 16S rRNA Sequencing Methods

2018 ◽  
Vol 101 (6) ◽  
pp. 1757-1762 ◽  
Author(s):  
Irshad M Sulaiman ◽  
Ying-Hsin Hsieh ◽  
Emily Jacobs ◽  
Nancy Miranda ◽  
Steven Simpson ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Sequencing ◽  
Gram Positive ◽  
Maldi Tof Ms ◽  
Lysinibacillus Fusiformis ◽  
Maldi Tof ◽  
Microbiological Methods ◽  
Rrna Sequencing ◽  
Level Identification ◽  
Tof Ms

Abstract Background: Lysinibacillus fusiformis is a Gram-positive, rod-shaped bacterium that can cause tropical ulcers, severe sepsis, and respiratory illnesses in humans. Objective: In this study, we analyzed cosmetic samples for the presence of human pathogenic microorganisms. Methods: Five unopened jars of exfoliating cream were examined initially by microbiological methods. Afterward, matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) MS and 16S ribosomal RNA (rRNA) sequencing techniques were applied to characterize the recovered isolates. Results: Of the eight recovered Gram-positive bacterial subs, the VITEK® MS could provide genus-level identification to five subs and species-level identification to two subs (L. fusiformis with a 99.9% confidence value); one sub was unidentified. Subsequently, the deoxyriboneucleic acid sequencing of the 16S rRNA gene was done on an ABI 3500XL Genetic Analyzer for the confirmation of species identification. An analysis of sequencing data revealed a complete absence of genetic variation among the eight subs sequenced at this locus and confirmed the eight bacterial subs to be L. fusiformis, as their respective 16S rRNA sequences were identical to the available sequence in public domain (GenBank accession No. KU179364). Conclusions: Our results suggest that the VITEK MS and the 16S rRNA sequencing can be used for the identification of human pathogenic bacteria of public health importance. Highlights: We characterized eight isolates of Lysinibacillus spp. from cosmetics by MALDI-TOF MS and 16S rRNA sequence analyses.

scholarly journals MALDI-TOF MS Genotyping of Polymorphisms Related to 1-Carbon Metabolism Using Common and Mass-Modified Terminators

2009 ◽  
Vol 55 (1) ◽  
pp. 139-149 ◽  
Author(s):  
Klaus Meyer ◽  
Åse Fredriksen ◽  
Per Magne Ueland
Keyword(s):  
Carbon Metabolism ◽  
Accurate Determination ◽  
Average Error ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Sufficient Power ◽  
Assay Performance ◽  
Allele Specific ◽  
Tof Ms

Abstract Background: Large cohort studies may provide sufficient power to disentangle the role of polymorphisms related to 1-carbon metabolism and chronic diseases, but they require fast, accurate, high-throughput genotyping techniques. MALDI-TOF mass spectrometry has been adapted to rapid fine mapping using various approaches for allele discrimination. We developed a genotyping method based on MALDI-TOF MS and compared assay performance for formats based on standard and mass-modified terminators. Methods: The assay includes 20 polymorphisms of 14 genes involved in 1-carbon metabolism (BHMT 742G>A, CBS 844ins68 and 699C>T, CTH 1364G>T, DHFR del19, NOS3 –786T>C and 894G>T, FOLR1 1314G>A, MTHFD1 –105T>C and 1958G>A, MTHFR 677C>T and 1298A>C, MTR 2756A>G, MTRR 66A>G and 524C>T, SLC19A1 80G>A, SHMT1 1420C>T, TCN2 67A>G and 776C>G, and TYMS 1494del6). Results: Missing calls were observed for 4.7% of the DNA samples, attributed to failed liquid sample handling. Highly accurate genotyping was obtained by mass-modified as well as standard ddNTPs, with an average error rate of ≤0.1% by analysis of sample duplicates. A semiquantitative approach enabled unambiguous identification of the CBS 844ins68. Cluster plots of the relative allele intensities showed allele-specific bias according to type of minisequencing terminator and revealed a potential structural variation in the BHMT gene. Conclusions: MALDI-TOF MS–based genotyping using either standard or mass-modified terminators allows the accurate determination of single nucleotides as well as structural genetic variants. This was demonstrated with 20 polymorphisms involved in 1-carbon metabolism.

scholarly journals Rapid identification of bovine mastitis pathogens by MALDI-TOF Mass Spectrometry

2018 ◽  
Vol 38 (4) ◽  
pp. 586-594 ◽  
Author(s):  
Patrícia A.C. Braga ◽  
Juliano L. Gonçalves ◽  
Juliana R. Barreiro ◽  
Christina R. Ferreira ◽  
Tiago Tomazi ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Large Scale ◽  
Bovine Mastitis ◽  
Species Level ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Alternative Method ◽  
Microbiological Methods ◽  
Identification Of Bacteria ◽  
Tof Ms

ABSTRACT: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been shown to be an alternative method for identification of bacteria via their protein profile spectra, being able to identify bacteria at the genus, species and even at subspecies level. With the aim of large-scale identification of pathogens causing mastitis by this platform, a total of 305 isolates of bacteria identified from cows with subclinical mastitis were analyzed by conventional microbiological culture (MC) as well as by MALDI-TOF MS coupled with Biotyper data processing. Approximately 89% of the identifications performed by MALDI-TOF MS were consistent with results obtained by MC. From the remaining isolates (11%), 6.3% of isolates were classified as misidentified (discordance for both genus and species level), and 4.7% showed identification agreement at the genus level but not at the species level, being classified as unidentified at species level. The disagreement results were mostly associated with identification of Streptococcus and Enterococcus species probably due to the narrow phenotypic similarity between these two genera. These disagreement results suggest that biochemical assays might be prone to identification errors and, MALDI-TOF MS therefore may be an alternative to overcome incorrect species-specific identification. Standard microbiological methods for bovine mastitis diagnosis are time consuming, laborious and prone to errors for some bacteria genera. In our study, we showed that MALDI-TOF MS coupled with Biotyper may be an alternative method for large-scale identification of bacteria isolated from milk samples compared to classical microbiological routine protocols.

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