scholarly journals Performance of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identifying Clinical Malassezia Isolates

2016 ◽  
Vol 55 (1) ◽  
pp. 90-96 ◽  
Author(s):  
Julie Denis ◽  
Marie Machouart ◽  
Florent Morio ◽  
Marcela Sabou ◽  
Catherine Kauffmann-LaCroix ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Content Type ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

ABSTRACT The genus Malassezia comprises commensal yeasts on human skin. These yeasts are involved in superficial infections but are also isolated in deeper infections, such as fungemia, particularly in certain at-risk patients, such as neonates or patients with parenteral nutrition catheters. Very little is known about Malassezia epidemiology and virulence. This is due mainly to the difficulty of distinguishing species. Currently, species identification is based on morphological and biochemical characteristics. Only molecular biology techniques identify species with certainty, but they are time-consuming and expensive. The aim of this study was to develop and evaluate a matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) database for identifying Malassezia species by mass spectrometry. Eighty-five Malassezia isolates from patients in three French university hospitals were investigated. Each strain was identified by internal transcribed spacer sequencing. Forty-five strains of the six species Malassezia furfur , M. sympodialis , M. slooffiae , M. globosa , M. restricta , and M. pachydermatis allowed the creation of a MALDI-TOF database. Forty other strains were used to test this database. All strains were identified by our Malassezia database with log scores of >2.0, according to the manufacturer's criteria. Repeatability and reproducibility tests showed a coefficient of variation of the log score values of <10%. In conclusion, our new Malassezia database allows easy, fast, and reliable identification of Malassezia species. Implementation of this database will contribute to a better, more rapid identification of Malassezia species and will be helpful in gaining a better understanding of their epidemiology.

scholarly journals Efficient Detection of Carbapenemase Activity in Enterobacteriaceae by Matrix-Assisted Laser Desorption Ionization−Time of Flight Mass Spectrometry in Less Than 30 Minutes

2015 ◽  
Vol 53 (7) ◽  
pp. 2163-2171 ◽  
Author(s):  
Camille Lasserre ◽  
Luc De Saint Martin ◽  
Gaelle Cuzon ◽  
Pierre Bogaerts ◽  
Estelle Lamar ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Content Type ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

The recognition of carbapenemase-producingEnterobacteriaceae(CPE) isolates is a major laboratory challenge, and their inappropriate or delayed detection may have negative impacts on patient management and on the implementation of infection control measures. We describe here a matrix-assisted laser desorption ionization−time of flight (MALDI-TOF)-based method to detect carbapenemase activity inEnterobacteriaceae. After a 20-min incubation of the isolate with 0.5 mg/ml imipenem at 37°C, supernatants were analyzed by MALDI-TOF in order to identify peaks corresponding to imipenem (300 Da) and an imipenem metabolite (254 Da). A total of 223 strains, 77 CPE (OXA-48 variants, KPC, NDM, VIM, IMI, IMP, and NMC-A) and 146 non-CPE (cephalosporinases, extended-spectrum β-lactamases [ESBLs], and porin defects), were tested and used to calculate a ratio of imipenem hydrolysis: mass spectrometry [MS] ratio = metabolite/(imipenem + metabolite). An MS ratio cutoff was statistically determined to classify strains as carbapenemase producers (MS ratio of ≥0.82). We validated this method first by testing 30 of our 223 isolates (15 CPE and 15 non-CPE) 10 times to calculate an intraclass correlation coefficient (ICC of 0.98), showing the excellent repeatability of the method. Second, 43 strains (25 CPE and 18 non-CPE) different from the 223 strains used to calculate the ratio cutoff were used as external controls and blind tested. They yielded sensitivity and specificity of 100%. The total cost per test is <0.10 U.S. dollars (USD). This easy-to-perform assay is time-saving, cost-efficient, and highly reliable and might be used in any routine laboratory, given the availability of mass spectrometry, to detect CPE.

scholarly journals Creation of an In-House Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Corynebacterineae Database Overcomes Difficulties in Identification of Nocardia farcinica Clinical Isolates

2015 ◽  
Vol 53 (8) ◽  
pp. 2611-2621 ◽  
Author(s):  
Mariola Paściak ◽  
Władysław Dacko ◽  
Joanna Sikora ◽  
Danuta Gurlaga ◽  
Krzysztof Pawlik ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Content Type ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

Nocardiosis is a rare disease that is caused by Gram-positive actinobacteria of theNocardiagenus and affects predominantly immunocompromised patients. In its disseminated form, it has a predilection for the central nervous system and is associated with high mortality rates. Therefore, prompt identification of the pathogen is critical. Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry is a relatively novel technique used for identification of microorganisms. In this work, an upgraded MALDI-TOF Biotyper database containingCorynebacterineaerepresentatives of strains deposited in the Polish Collection of Microorganisms was created and used for identification of the strain isolated from a nocardial brain abscess, mimicking a brain tumor, in an immunocompetent patient. Testing with the API Coryne system initially incorrectly identifiedRhodococcussp., while chemotaxonomic tests, especially mycolic acid analysis, enabled correctNocardiaidentification only at the genus level. Subsequent sequence analysis of 16S rRNA andsecA1genes confirmed the identification. To improve the accuracy of the results, an in-house database was constructed using optimized parameters; with the use of the database, the strain was eventually identified asNocardia farcinica. Clinical laboratories processing various clinical strains can upgrade a commercial database to improve and to accelerate the results obtained. This is especially important in the case ofNocardia, for which valid microbial diagnosis remains challenging; reference laboratories are often required to identify and to survey these rare actinobacteria.

scholarly journals Rapid and Robust Identification of the Agents of Black-Grain Mycetoma by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

2017 ◽  
Vol 55 (8) ◽  
pp. 2521-2528 ◽  
Author(s):  
Mark Fraser ◽  
Andrew M. Borman ◽  
Elizabeth M. Johnson
Keyword(s):  
Mass Spectrometry ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Accurate Identification ◽  
Ionization Time ◽  
Content Type ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

ABSTRACTEumycetoma, a chronic fungal infection endemic in India, Indonesia, and parts of Africa and South and Central America, follows traumatic implantation of saprophytic fungi and frequently requires radical surgery or amputation in the absence of appropriate treatment. Fungal species that can cause black-grain mycetomas includeMadurellaspp.,Falciformisporaspp.,Trematosphaeria grisea,Nigrograna mackinnonii,Pseudochaetosphaeronema larense,Medicopsis romeroi, andEmarelliaspp.Rhytidhysteron rufulumandParathyridaria percutaneacause similar subcutaneous infections, but these infections lack the draining sinuses and fungal grains characteristic of eumycetoma. Accurate identification of the agents of subcutaneous fungal infection is essential to guide appropriate antifungal therapy. Since phenotypic identification of the causative fungi is often difficult, time-consuming molecular approaches are currently required. In the study described here we evaluated whether matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry might allow the accurate identification of eumycetoma agents and related fungi. A panel of 57 organisms corresponding to 10 different species from confirmed cases of eumycetoma and subcutaneous pedal masses, previously formally identified by PCR amplification and sequencing of internal transcribed spacer 1 (ITS1), was employed. Representative isolates of each species were used to create reference MALDI-TOF spectra, which were then used for the identification of the remaining isolates in a user-blinded manner. Here, we demonstrate that MALDI-TOF mass spectrometry accurately identified all of the test isolates, with 100%, 90.4%, and 67.3% of isolates achieving log scores greater than 1.8, 1.9, and 2.0, respectively.

Can Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF) Enhance Antimicrobial Stewardship Efforts in the Acute Care Setting?

2013 ◽  
Vol 34 (9) ◽  
pp. 990-995 ◽  
Author(s):  
Pranita D. Tamma ◽  
Kennard Tan ◽  
Veronique R. Nussenblatt ◽  
Alison E. Turnbull ◽  
Karen C. Carroll ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Flight Mass Spectrometry ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

We evaluated 222 hospitalized patients whose clinical isolates were tested using standard methods and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF). MALDI-TOF could have reduced time to appropriate therapy for 28.8% and 44.6% patients based on the treating physician's choices and stewardship team recommendations, respectively. Clinicians should be aware of scenarios in which MALDI-TOF can optimize antibiotic therapy.

scholarly journals Peaks of Promise and Peril: Screening for Antibiotic Resistance by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

2015 ◽  
Vol 54 (1) ◽  
pp. 5-6 ◽  
Author(s):  
Neil W. Anderson
Keyword(s):  
Mass Spectrometry ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Maldi Tof Mass Spectrometry ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

An article in this issue of theJournal of Clinical Microbiology(J.-H. Youn, S. K. Drake, R. A. Weingarten, K. M. Frank, J. P. Dekker, and A. F. Lau, J Clin Microbiol 53:35–42, 2015,http://dx.doi.org/10.1128/JCM.01643-15) describes the use of matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry for the detection of organisms carrying ablaKPC-containing plasmid. This powerful and promising application highlights the challenges of using MALDI-TOF mass spectrometry for purposes other than organism identification.

scholarly journals Performance of Matrix-Assisted Laser Desorption Ionization−Time of Flight Mass Spectrometry for Identification of Aspergillus, Scedosporium, and Fusarium spp. in the Australian Clinical Setting

2016 ◽  
Vol 54 (8) ◽  
pp. 2182-2186 ◽  
Author(s):  
Sue Sleiman ◽  
Catriona L. Halliday ◽  
Belinda Chapman ◽  
Mitchell Brown ◽  
Joanne Nitschke ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Content Type ◽  
Desorption Ionization ◽  
Flight Mass Spectrometry ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

We developed an Australian database for the identification ofAspergillus,Scedosporium, andFusariumspecies (n= 28) by matrix-assisted laser desorption ionization−time of flight mass spectrometry (MALDI-TOF MS). In a challenge against 117 isolates, species identification significantly improved when the in-house-built database was combined with the Bruker Filamentous Fungi Library compared with that for the Bruker library alone (Aspergillus, 93% versus 69%;Fusarium, 84% versus 42%; andScedosporium, 94% versus 18%, respectively).

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