Identification of Dermatophyte Species after Implementation of the In-House MALDI-TOF MS Database

Calderaro, Adriana; Motta, Federica; Montecchini, Sara; Gorrini, Chiara; Piccolo, Giovanna; Piergianni, Maddalena; Buttrini, Mirko; Medici, Maria Cristina; Arcangeletti, Maria Cristina; Chezzi, Carlo; Conto, Flora De

doi:10.3390/ijms150916012

Cited by 34 publications

(49 citation statements)

References 18 publications

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“…Prior studies have evaluated the accuracy of MALDI-TOF MS for the identification of only a few genera or groups of organisms, such as Aspergillus spp. or the dermatophytes (12,13,(19)(20)(21)(22)(23)(24)(25)(26). In our study, which examined 319 isolates from 43 different genera, the Vitek MS version 3.0 library was able to correctly identify 66.8% of isolates and 76.8% of the isolates after additional SARAMIS analysis.…”

Section: Discussionmentioning

confidence: 75%

Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Clinically Relevant Filamentous Fungi

et al. 2016

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bInvasive fungal infections have a high rate of morbidity and mortality, and accurate identification is necessary to guide appropriate antifungal therapy. With the increasing incidence of invasive disease attributed to filamentous fungi, rapid and accurate species-level identification of these pathogens is necessary. Traditional methods for identification of filamentous fungi can be slow and may lack resolution. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a rapid and accurate method for identification of bacteria and yeasts, but a paucity of data exists on the performance characteristics of this method for identification of filamentous fungi. The objective of our study was to evaluate the accuracy of the Vitek MS for mold identification. A total of 319 mold isolates representing 43 genera recovered from clinical specimens were evaluated. Of these isolates, 213 (66.8%) were correctly identified using the Vitek MS Knowledge Base, version 3.0 database. When a modified SARAMIS (Spectral Archive and Microbial Identification System) database was used to augment the version 3.0 Knowledge Base, 245 (76.8%) isolates were correctly identified. Unidentified isolates were subcultured for repeat testing; 71/ 319 (22.3%) remained unidentified. Of the unidentified isolates, 69 were not in the database. Only 3 (0.9%) isolates were misidentified by MALDI-TOF MS (including Aspergillus amoenus [n ‫؍‬ 2] and Aspergillus calidoustus [n ‫؍‬ 1]) although 10 (3.1%) of the original phenotypic identifications were not correct. In addition, this methodology was able to accurately identify 133/144 (93.6%) Aspergillus sp. isolates to the species level. MALDI-TOF MS has the potential to expedite mold identification, and misidentifications are rare. Filamentous fungi are ubiquitous environmental microorganisms that have become increasingly important pathogens, especially in immunocompromised patients. Invasive fungal diseases have a high rate of morbidity and mortality, and accurate identification is necessary to guide appropriate antifungal therapy. Traditionally, the identification of filamentous fungi has required the use of different phenotypic methods in conjunction with macro-and microscopic assessment of the organism (1). This process requires highly trained mycologists, and, in some cases, turnaround time may be prolonged due to a requirement for extended incubation periods, potentially delaying appropriate therapy. Molecular methods, which can provide accurate identification to the species level, can be expensive, require specialized equipment or expertise, and are not commonly available in clinical laboratories.Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been utilized in the clinical microbiology laboratory for rapid and accurate identification of bacteria, mycobacteria, and yeasts (2-9). For filamentous fungi, databases have been limited, and unlike bacteria, filamentous fungi require additional processing steps to dis...

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Section: Discussionmentioning

confidence: 75%

Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Clinically Relevant Filamentous Fungi

et al. 2016

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“…All 64 isolates were correctly identified (score value of Ͼ2.0 for 47 isolates and score value of 1.7 to 2.0 for the remaining 17 isolates) with the implemented database, including the M. audouinii isolate (misidentified as M. canis), 2 T. violaceum isolates (not reliably identified; score value of Ͻ1.7), 1 T. tonsurans isolate (misidentified as T. rubrum), 3 T. rubrum isolates (2 misidentified as T. tonsurans and 1 not reliably identified), 2 T. soudanense isolates (1 misidentified as T. rubrum and 1 not reliably identified), and 1 M. persicolor isolate (not reliably identified). As expected, with regard to T. mentagrophytes-T. interdigitale isolates (19 and 2, respectively; not distinguished by their ITS sequences), all but 2 isolates were misidentified as T. tonsurans: 1 of the 2 isolates was misidentified as M. gypseum, and the other one was not reliably identified (32). A more recent evaluation of the performance of the Bruker Biotyper system showed that MALDI-TOF MS provided correct genus-level and species-level identifications for 96.8% (122/126) and 87.9% (113/126) of dermatophyte isolates, respectively, using a supplemented database (the MALDI Biotyper Support Library, i.e., created by adding spectra from 10 reference dermatophyte strains) and decreased score values (33).…”

Section: Rhizopus-lichtheimia Species Previous Reports On the Maldi-mentioning

confidence: 80%

“…It is worth noting that A. flavus, the second leading cause of human aspergillosis, is not separable from Aspergillus oryzae by means of molecular biology techniques, whereas the closely related species T. mentagrophytes and T. interdigitale are not separable by means of ITS sequence analysis. In contrast, MALDI-TOF MS seems to be more powerful for discrimination between these species (10,32) as well as to distinguish clinically relevant from irrelevant species of Lichtheimia (26). However, as MALDI-TOF MS-based identification should be consistent with the aspect of the organism in culture, relatively mature growth must be achieved before the identification is certain.…”

Section: Mold Identification By Maldi-tof Ms: Is It Really a History mentioning

confidence: 99%

“…Although these methods can provide accurate results, they are expensive, require specialized equipment or expertise, and are not commonly available in clinical laboratories. In the present review, findings from the 10 studies (23)(24)(25)(27)(28)(29)(30)(31)(32)(33) shown in Table 1 indicate that before MALDI-TOF MS testing, only one study identified isolates via conventional phenotypical analyses (33), whereas almost all the remaining studies also sequenced all their isolates, and in two studies, only molecular biology analyses of the isolates were undertaken (27,28). This supports the idea that the overall high level of accuracy of MALDI-TOF MS-based mold identification shown in these studies might not be overestimated.…”

Section: Mold Identification By Maldi-tof Ms: Is It Really a History mentioning

confidence: 99%

“…For 10 taxa, the rate of correct identifications was 100%, including Trichophyton erinacei (1 isolate) and Trichophyton terrestre (1 isolate); in contrast, only 15 of 19 (78.9%) African Trichophyton rubrum (also called Trichophyton soudanense) isolates were correctly identified (this rate was clearly lower than that for T. rubrum sensu stricto isolates [100%]), with several isolates being misidentified as Trichophyton violaceum, demonstrating the close relationship of these two taxa (31). Later, in another study, the Bruker Biotyper database was supplemented with additional mass spectra from 24 (13 reference [United Kingdom National External Quality Assessment Service {UK NEQAS}] and 11 clinical) morphologically and/or molecularly (i.e., by ITS DNA sequencing) characterized strains of 13 different species (32). Together with dermatophyte species already existing in the original database (i.e., Epidermophyton floccosum, Microsporum canis, Microsporum gypseum, T. rubrum, Trichophyton interdigitale, Trichophyton mentagrophytes, and T. tonsurans), the newly added species included three Microsporum species (M. fulvum, M. persicolor, and M. audouinii) and three Trichophyton species (T. erinacei, T. violaceum, and T. soudanense).…”

Section: Rhizopus-lichtheimia Species Previous Reports On the Maldi-mentioning

confidence: 99%

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Identification of Molds by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Sanguinetti

2017

J Clin Microbiol

121

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Although to a lesser extent than diagnostic bacteriology, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently revolutionized the diagnostic mycology workflow. With regard to filamentous fungi (or molds), the precise recognition of pathogenic species is important for rapid diagnosis and appropriate treatment, especially for invasive diseases. This review summarizes the current experience with MALDI-TOF MS-based identification of common and uncommon mold species of Aspergillus, Fusarium, Mucorales, dimorphic fungi, and dermatophytes. This experience clearly shows that MALDI-TOF MS holds promise as a fast and accurate identification tool, particularly with common species or typical strains of filamentous fungi.

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Recent advances in the diagnosis of dermatophytosis

et al. 2020

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Dermatophytosis is a disease of global significance caused by pathogenic keratinolytic fungi called dermatophytes in both animals and humans. The recent taxonomy of dermatophytes classifies them into six pathogenic genera, namely Microsporum, Trichophyton, Epidermophyton, Nannizzia, Lophophyton and Arthroderma. It is because of the delayed diagnostic nature and low accuracy of dermatophyte detection by conventional methods that paved the path for the evolution of molecular diagnostic techniques, which provide the accurate and rapid diagnosis of dermatophytosis for an appropriate, timely antifungal therapy that prevents the nonspecific over‐the‐counter self‐medication. This review focuses on the importance of rapid and accurate diagnosis of dermatophytosis, limitations of conventional methods, selection of targets in diagnosis, and factors affecting sensitivity and specificity of various molecular diagnostic technologies in the diagnosis of dermatophytosis. Generally, all the molecular techniques have a significant edge over the conventional methods of culture and microscopy in the dermatophytosis diagnosis. However, in mycology laboratory, the suitability of any molecular diagnostic technique in the diagnosis of dermatophytosis is driven by the requirement of time, economy, complexity, the range of species spectrum detected and the scale of diagnostic output required. Thus, various choices involved in the pursuit of a diagnosis of dermatophytosis are determined by the available conditions and the facilities in the laboratory.

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Identification of Dermatophyte Species after Implementation of the In-House MALDI-TOF MS Database

Cited by 34 publications

References 18 publications

Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Clinically Relevant Filamentous Fungi

Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Clinically Relevant Filamentous Fungi

Identification of Molds by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Recent advances in the diagnosis of dermatophytosis

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