MALDI-TOF MS in a Medical Mycology Laboratory: On Stage and Backstage

The implementation of MALDI-TOF MS in medical microbiology laboratories has revolutionized practices and significantly reduced turnaround times of identification processes. However, although bacteriology quickly benefited from the contributions of this technique, adjustments were necessary to accommodate the specific characteristics of fungi. MALDI-TOF MS is now an indispensable tool in clinical mycology laboratories, both for the identification of yeasts and filamentous fungi, and other innovative uses are gradually emerging. Based on the practical experience of our medical mycology laboratory, this review will present the current uses of MALDI-TOF MS and the adaptations we implemented, to allow their practical execution in a daily routine. We will also introduce some less mainstream applications, like those for fungemia, or even still under development, as is the case for the determination of sensitivity to antifungal agents or typing methods.

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Rapid Classification of Clostridioides difficile Strains Using MALDI-TOF MS Peak-Based Assay in Comparison with PCR-Ribotyping

Microorganisms ◽

10.3390/microorganisms9030661 ◽

2021 ◽

Vol 9 (3) ◽

pp. 661

Author(s):

Adriana Calderaro ◽

Mirko Buttrini ◽

Monica Martinelli ◽

Benedetta Farina ◽

Tiziano Moro ◽

...

Keyword(s):

Ionization Time ◽

Maldi Tof Ms ◽

Maldi Tof ◽

Flight Mass Spectrometry ◽

Clostridioides Difficile ◽

Pcr Ribotyping ◽

Typing Methods ◽

Set Up ◽

Tof Ms

Typing methods are needed for epidemiological tracking of new emerging and hypervirulent strains because of the growing incidence, severity and mortality of Clostridioides difficile infections (CDI). The aim of this study was the evaluation of a typing Matrix-Assisted Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS (T-MALDI)) method for the rapid classification of the circulating C. difficile strains in comparison with polymerase chain reaction (PCR)-ribotyping results. Among 95 C. difficile strains, 10 ribotypes (PR1–PR10) were identified by PCR-ribotyping. In particular, 93.7% of the isolates (89/95) were grouped in five ribotypes (PR1–PR5). For T-MALDI, two classifying algorithm models (CAM) were tested: the first CAM involved all 10 ribotypes whereas the second one only the PR1–PR5 ribotypes. Better performance was obtained using the second CAM: recognition capability of 100%, cross-validation of 96.6% and agreement of 98.4% (60 correctly typed strains, limited to PR1–PR5 classification, out of 61 examined strains) with PCR-ribotyping results. T-MALDI seems to represent an alternative to PCR-ribotyping in terms of reproducibility, set up time and costs, as well as a useful tool in epidemiological investigation for the detection of C. difficile clusters (either among CAM included ribotypes or out-of-CAM ribotypes) involved in outbreaks.

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From days to hours: Can MALDI-TOF MS system replace both conventional and molecular typing methods with new cut off level for Vancomycin Resistant Enterococcus faecium

Journal of Microbiological Methods ◽

10.1016/j.mimet.2018.12.015 ◽

2019 ◽

Vol 162 ◽

pp. 62-68 ◽

Cited By ~ 2

Author(s):

Sumeyra Savas ◽

Gulsen Hazirolan ◽

Alper Karagoz ◽

Mehmet Parlak

Keyword(s):

Enterococcus Faecium ◽

Molecular Typing ◽

Vancomycin Resistant Enterococcus ◽

Maldi Tof Ms ◽

Maldi Tof ◽

Typing Methods ◽

Vancomycin Resistant ◽

Tof Ms

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Overestimated discriminatory power of MALDI-TOF mass spectrometry for typing of carbapenem-resistant Klebsiella pneumoniae clones

Epidemiology and Infection ◽

10.1017/s0950268819002097 ◽

2019 ◽

Vol 147 ◽

Cited By ~ 3

Author(s):

Fei Jiang ◽

Ziyan Kong ◽

Chen Cheng ◽

Haiquan Kang ◽

Bing Gu ◽

...

Keyword(s):

Klebsiella Pneumoniae ◽

Taxonomic Diversity ◽

Discriminatory Power ◽

Adjusted Rand Index ◽

Maldi Tof Ms ◽

Maldi Tof ◽

Carbapenem Resistant ◽

Typing Methods ◽

Sequence Types ◽

Tof Ms

Abstract Homology surveillance of carbapenem-resistant Klebsiella pneumoniae (CRKP) is critical to monitor and prevent outbreaks of nosocomial infections. In the present study, a matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF MS)-based method was evaluated as a rapid tool for typing CRKP in comparison with pulsed-field gel electrophoresis (PFGE) and multi locus sequence typing (MLST). Drug-resistant phenotypes and genotypes of 44 CRKP isolates were detected by microdilution broth method and polymerase chain reaction, and typed by PFGE, MLST and MALDI-TOF MS. Simpson's Index of Diversity was used to evaluate taxonomic diversity, Adjusted Rand Index (ARI) for congruence between the typing methods and Wallace coefficients (W) for the ability of either method to predict each other. Forty-four CRKP isolates of 15 sequence types (STs) produced either NDM-1 (n = 16), NDM-5 (n = 9) or KPC-2 (n = 19) carbapenemases. PFGE differentiated these isolates into 16 distinct types, and two deoxyribonucleic acid profiles were assigned to ST337 and ST11, respectively. MALDI-TOF MS failed to clearly delineate between clusters on dendrograms based on principal components analysis and main spectrum profile. The chosen parameters resulted in a maximum ARI of 0.310 (95% CI 0.088–0.531) between MALDI-TOF MS typing and the PFGE reference, indicating a low ability of the former to correctly identify related isolates. Likewise, the maximum W coefficient of 0.367 (95% CI 0.203–0.532) showed that MALDI-TOF MS had a lower predictive power than PFGE. We conclude that MALDI-TOF MS lacks the discriminatory power necessary for clone assignment of CRKP isolates and consequently cannot be considered as a rapid and creditable method for this purpose.

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MALDI-TOF-MS-based species identification and typing approaches in medical mycology

PROTEOMICS ◽

10.1002/pmic.201200468 ◽

2013 ◽

Vol 13 (5) ◽

pp. 788-799 ◽

Cited By ~ 96

Author(s):

Oliver Bader

Keyword(s):

Species Identification ◽

Medical Mycology ◽

Maldi Tof Ms ◽

Maldi Tof ◽

Tof Ms

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Usefulness of MALDI-TOF and REP-PCR against PFGE for the epidemiological study of Acinetobacter baumannii

Revista Española de Quimioterapia ◽

10.37201/req/142.2020 ◽

2021 ◽

Author(s):

Cristina García-Salguero ◽

◽

Esther Culebras ◽

Adela Alvarez-Buylla ◽

Icíar Rodríguez-Avial ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

Epidemiological Study ◽

Gel Electrophoresis ◽

Pulsed Field Gel Electrophoresis ◽

Pcr Analysis ◽

Maldi Tof Ms ◽

Clonal Group ◽

Maldi Tof ◽

Typing Methods ◽

Tof Ms

Objective. To evaluate the ability of MALDI-TOF MS and rep-PCR to discriminate Acinetobacter baumannii clones. Material and methods. A total of 21 strains of A. baumannii with different epidemiological and phenotipycal characteristics were included in the study. All isolates were analyzed in parallel by MALDI-TOF MS and rep-PCR and the spectra obtained were compared with each other and with the results obtained by pulsed field gel electrophoresis (PFGE). Isolates with a similarity equal to or greater than 87% were considered to be part of the same clonal group. Results. The analysis of the 21 isolates included in the study, resulted in 8 clonal groups using PFGE, 3 groups by MALDI-TOF MS and 7 groups by rep-PCR analysis. The isolates that formed the different groups by the 3 techniques used were totally different, so it can be concluded that there is no equivalence between the results obtained with the three typing methods used. Conclusions. Despite its simplicity, neither MALDI-TOF MS nor rep-PCR can at this time replace PFGE for the epidemiological study of A. baumannii.

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