Evaluation of Vitek MS for Differentiation of
 Cryptococcus neoformans
 and
 Cryptococcus gattii
 Genotypes

Siqueira, Lumena Pereira Machado; Gimenes, Viviane Mazo Fávero; Freitas, Roseli Santos de; Melhem, Márcia de Souza Carvalho; Bonfietti, Lucas Xavier; Silva, Afonso Rafael da; Santos, Letícia Bernabé; Motta, Adriana; Rossi, Flávia; Benard, Gil; Almeida, João Nóbrega de

doi:10.1128/jcm.01282-18

Cited by 22 publications

(8 citation statements)

References 23 publications

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“…These results are in agreement with those shown in previous studies that report improved identification of Cryptococcus species based on MALDI-TOF MS and the implementation of extended in-house libraries: Firacative et al and Siqueira et al reported 100% correct molecular-type identifications [ 23 , 27 ] and Posteraro et al 98.8% unambiguous discrimination at the same level [ 28 ]. On the other hand, McTaggart et al also showed 98.8% species-level identification although in their case no interspecies hybrids were included in the study [ 22 ].…”

Section: Discussionsupporting

confidence: 92%

Implementation of MALDI-TOF Mass Spectrometry and Peak Analysis: Application to the Discrimination of Cryptococcus neoformans Species Complex and Their Interspecies Hybrids

Zvezdánova

Arroyo

Méndez

et al. 2020

JoF

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Matrix-assisted laser desorption–ionization/time of flight mass spectrometry (MALDI-TOF MS) has been widely implemented for the rapid identification of microorganisms. Although most bacteria, yeasts and filamentous fungi can be accurately identified with this method, some closely related species still represent a challenge for MALDI-TOF MS. In this study, two MALDI-TOF-based approaches were applied for discrimination at the species-level of isolates belonging to the Cryptococcus neoformans complex, previously characterized by Amplified Fragment Length Polymorphism (AFLP) and sequencing of the ITS1-5.8S-ITS2 region: (i) an expanded database was built with 26 isolates from the main Cryptococcus species found in our setting (C. neoformans, C. deneoformans and AFLP3 interspecies hybrids) and (ii) peak analysis and data modeling were applied to the protein spectra of the analyzed Cryptococcus isolates. The implementation of the in-house database did not allow for the discrimination of the interspecies hybrids. However, the performance of peak analysis with the application of supervised classifiers (partial least squares-discriminant analysis and support vector machine) in a two-step analysis allowed for the 96.95% and 96.55% correct discrimination of C. neoformans from the interspecies hybrids, respectively. In addition, PCA analysis prior to support vector machine (SVM) provided 98.45% correct discrimination of the three analyzed species in a one-step analysis. This novel method is cost-efficient, rapid and user-friendly. The procedure can also be automatized for an optimized implementation in the laboratory routine.

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Section: Discussionsupporting

confidence: 92%

Implementation of MALDI-TOF Mass Spectrometry and Peak Analysis: Application to the Discrimination of Cryptococcus neoformans Species Complex and Their Interspecies Hybrids

Zvezdánova

Arroyo

Méndez

et al. 2020

JoF

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“…This goal was only fulfilled completely when peak analysis was performed and the three Cryptococcus species analyzed in this study distinctively clustered together. Other authors have provided species-level discrimination in 98.1-100% of the cases [21,23,27]. Although some of these studies were performed on higher number of isolates, our results also reflect the improvements made on the commercial database during the last years.…”

Section: Discussionsupporting

confidence: 73%

Implementation of MALDI-TOF Mass Spectrometry and Peak Analysis: Application to the Discrimination of Cryptococcus Species and Their Interspecies Hybrids

Zvezdánova¹,

Arroyo²,

Méndez³

et al. 2020

Preprint

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MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization Time-of Flight) is a type of mass spectrometry (MS) that has been widely implemented for the rapid identification of microorganisms over the last decade. The accuracy and flexibility of this method has encouraged researchers to implement the analysis of protein spectra obtained by MALDI-TOF for the discrimination of close-related species and bacterial typing. In this study, a standardized methodology based on the detection of species-specific protein peaks from the spectra obtained with MALDI-TOF is described. The methodology was applied to a collection of Cryptococcus spp. (n=70) previously characterized by Amplified Fragment Length Polymorphism (AFLP) and sequencing of the ITS1-5.8S-ITS2 region. An expanded ad-hoc database was also built for their discrimination with MALDI-TOF. This approach did not allow the discrimination of the interspecies hybrids. However, the performance of peak analysis with the application of the PLS-DA and SVM algorithms in a two-step analysis allowed 96.95% and 96.55% correct discrimination of C. neoformans from the interspecies hybrids, respectively. Besides, PCA analysis prior to SVM provided 98.45% correct discrimination of the 3 analyzed species in a one-step analysis. The method is cost-efficient, rapid and user-friendly. The procedure can also be automatized for an optimized implementation in the laboratory routine.

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“…However, using the respective research only software (RUO), and particularly with complementation with in-house generated spectra, rapid and reliable identification is readily achieved. Furthermore, accurate identification of all the genotypes of C. neoformans and C. gattii has been reported [107,108,109].…”

Section: Diagnosismentioning

confidence: 99%

Central Nervous System Cryptococcal Infections in Non-HIV Infected Patients

Beardsley

Sorrell

Chen

2019

JoF

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Central nervous system (CNS) cryptococcosis in non-HIV infected patients affects solid organ transplant (SOT) recipients, patients with malignancy, rheumatic disorders, other immunosuppressive conditions and immunocompetent hosts. More recently described risks include the use of newer biologicals and recreational intravenous drug use. Disease is caused by Cryptococcus neoformans and Cryptococcus gattii species complex; C. gattii is endemic in several geographic regions and has caused outbreaks in North America. Major virulence determinants are the polysaccharide capsule, melanin and several ‘invasins’. Cryptococcal plb1, laccase and urease are essential for dissemination from lung to CNS and crossing the blood–brain barrier. Meningo-encephalitis is common but intracerebral infection or hydrocephalus also occur, and are relatively frequent in C. gattii infection. Complications include neurologic deficits, raised intracranial pressure (ICP) and disseminated disease. Diagnosis relies on culture, phenotypic identification methods, and cryptococcal antigen detection. Molecular methods can assist. Preferred induction antifungal therapy is a lipid amphotericin B formulation (amphotericin B deoxycholate may be used in non-transplant patients) plus 5-flucytosine for 2–6 weeks depending on host type followed by consolidation/maintenance therapy with fluconazole for 12 months or longer. Control of raised ICP is essential. Clinicians should be vigilant for immune reconstitution inflammatory syndrome.

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Evaluation of Vitek MS for Differentiation of Cryptococcus neoformans and Cryptococcus gattii Genotypes

Cited by 22 publications

References 23 publications

Implementation of MALDI-TOF Mass Spectrometry and Peak Analysis: Application to the Discrimination of Cryptococcus neoformans Species Complex and Their Interspecies Hybrids

Implementation of MALDI-TOF Mass Spectrometry and Peak Analysis: Application to the Discrimination of Cryptococcus neoformans Species Complex and Their Interspecies Hybrids

Implementation of MALDI-TOF Mass Spectrometry and Peak Analysis: Application to the Discrimination of <em>Cryptococcus</em> Species and Their Interspecies Hybrids

Central Nervous System Cryptococcal Infections in Non-HIV Infected Patients

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