Evaluation of the Bruker MALDI Biotyper for Identification of Gram-Positive Rods: Development of a Diagnostic Algorithm for the Clinical Laboratory

Schulthess, Bettina; Bloemberg, Guido V.; Zbinden, Reinhard; Böttger, Erik C.; Hombach, Michael

doi:10.1128/jcm.02399-13

Cited by 109 publications

(89 citation statements)

References 32 publications

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“…In addition, optimal sample preparation of molds for identification by the Bruker MALDI Biotyper requires-according to the manufacturer-a liquid subculture and the ethanol-formic acid extraction procedure. This procedure is more time-consuming than the direct transfer preparation protocol that is suitable to identify most bacteria (24,25). Collecting fungal material directly from solid medium (agar plates) instead of harvesting it from liquid subculture has been proposed by others and could simplify sample preparation and save time (14,15,19,23,28).…”

Section: Discussionmentioning

confidence: 99%

“…Species inconsistencies at a cutoff of 1.7 were observed especially for Aspergillus glaucus, Aspergillus unguis, Fusarium spp., and Penicillium spp. To minimize this problem, we suggest using a two-step interpretation as has previously been proposed for the identification of Gram-positive rod-shaped bacteria: in a first step, data interpretation is done according to the standard criteria (species cutoff of 2.0), and in a second step, a lower species cutoff (preferably 1.7) is applied for those isolates that did not yield species identification when using the standard species cutoff value of 2.0 (25).…”

Section: Discussionmentioning

confidence: 99%

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Use of the Bruker MALDI Biotyper for Identification of Molds in the Clinical Mycology Laboratory

et al. 2014

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Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is increasingly used for the identification of bacteria and fungi in the diagnostic laboratory. We evaluated the mold database of Bruker Daltonik (Bremen, Germany), the Filamentous Fungi Library 1.0. First, we studied 83 phenotypically and molecularly well-characterized, nondermatophyte, nondematiaceous molds from a clinical strain collection. Using the manufacturer-recommended interpretation criteria, genus and species identification rates were 78.3% and 54.2%, respectively. Reducing the species cutoff from 2.0 to 1.7 significantly increased species identification to 71.1% without increasing misidentifications. In a subsequent prospective study, 200 consecutive clinical mold isolates were identified by the MALDI Biotyper and our conventional identification algorithm. Discrepancies were resolved by ribosomal DNA (rDNA) internal transcribed spacer region sequence analysis. For the MALDI Biotyper, genus and species identification rates were 83.5% and 79.0%, respectively, when using a species cutoff of 1.7. Not identified were 16.5% of the isolates. Concordant genus and species assignments of MALDI-TOF MS and the conventional identification algorithm were observed for 98.2% and 64.2% of the isolates, respectively. Four erroneous species assignments were observed using the MALDI Biotyper. The MALDI Biotyper seems highly reliable for the identification of molds when using the Filamentous Fungi Library 1.0 and a species cutoff of 1.7. However, expansion of the database is required to reduce the number of nonidentified isolates. Molds are an important cause of morbidity and mortality among hospitalized patients, particularly among those who are immunocompromised or suffer from serious underlying disease (1-3). Traditionally, identification of molds in the diagnostic mycology laboratory is based on phenotypic traits (4-6). Sufficient growth and sporulation are required to assess macromorphological criteria, including growth on different media and at different temperatures, as well as micromorphological criteria, such as shape of conidia, spores, and mycelial structures. Conventional identification methods have important drawbacks: (i) conventional identification of molds requires a comparably long time to result, (ii) the enormous morphological variability of molds asks for extensive individual expertise of the laboratory personnel, and (iii) some mold isolates do not develop their characteristic structural features under laboratory conditions, preventing identification or even leading to misidentifications. Nucleic acid sequence analysis of the internal transcribed spacer (ITS) regions between the 18S and 28S rRNA genes has emerged as an alternative to conventional identification, especially for isolates with unusual phenotypic profiles and rare molds, including environmental contaminants (4, 7-9).Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is increasingly used in diagnostic bacter...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Use of the Bruker MALDI Biotyper for Identification of Molds in the Clinical Mycology Laboratory

et al. 2014

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“…While some participants routinely utilize the so-called direct transfer method (30,32) and/or the ethanol-formic acid (FA) protocol recommended by Bruker Daltonics (30,33), the group at RKI primarily uses the trifluoroacetic acid (TFA) inactivation/sample preparation method (34). A large advantage of inactivation by gamma irradiation is that this method is compatible with all of these sample preparation protocols: microbial isolates inactivated by gamma irradiation can in principle be further processed by utilizing any of the different laboratory-specific methodologies.…”

Section: Methodsmentioning

confidence: 99%

Identification of Highly Pathogenic Microorganisms by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry: Results of an Interlaboratory Ring Trial

et al. 2015

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mIn the case of a release of highly pathogenic bacteria (HPB), there is an urgent need for rapid, accurate, and reliable diagnostics. MALDI-TOF mass spectrometry is a rapid, accurate, and relatively inexpensive technique that is becoming increasingly important in microbiological diagnostics to complement classical microbiology, PCR, and genotyping of HPB. In the present study, the results of a joint exercise with 11 partner institutions from nine European countries are presented. In this exercise, 10 distinct microbial samples, among them five HPB, Bacillus anthracis, Brucella canis, Burkholderia mallei, Burkholderia pseudomallei, and Yersinia pestis, were characterized under blinded conditions. Microbial strains were inactivated by high-dose gamma irradiation before shipment. Preparatory investigations ensured that this type of inactivation induced only subtle spectral changes with negligible influence on the quality of the diagnosis. Furthermore, pilot tests on nonpathogenic strains were systematically conducted to ensure the suitability of sample preparation and to optimize and standardize the workflow for microbial identification. The analysis of the microbial mass spectra was carried out by the individual laboratories on the basis of spectral libraries available on site. All mass spectra were also tested against an in-house HPB library at the Robert Koch Institute (RKI). The averaged identification accuracy was 77% in the first case and improved to >93% when the spectral diagnoses were obtained on the basis of the RKI library. The compilation of complete and comprehensive databases with spectra from a broad strain collection is therefore considered of paramount importance for accurate microbial identification. Highly pathogenic bacteria (HPB) are risk group 3 bacteria, which are defined as biological agents that can cause severe human disease and present a serious hazard to health care workers. This may present a risk of spreading to the community, but there is usually effective prophylaxis or treatment available (1). To this group belong bacteria such as Bacillus anthracis, Francisella tularensis subsp. tularensis (type A), Yersinia pestis, species of the Brucella melitensis group, Burkholderia mallei, and Burkholderia pseudomallei. HPB have the potential to be used in bioterrorist attacks (2, 3). The Centers for Disease Control and Prevention (CDC, Atlanta, GA) have classified B. anthracis, F. tularensis, and Y. pestis as category A and Brucella species, B. mallei, B. pseudomallei, and Coxiella burnetii as category B, comprising the main pathogens of concern for use in bioterrorist attacks (4). These pathogens may cause anthrax, tularemia, plague, brucellosis, glanders, melioidosis, and Q fever, respectively. In most parts of the world, the natural prevalence of these agents is low, even though some of these agents cause outbreaks in human and animal populations from time to time (5-8). The intentional release of these agents, however, can result in severe public health consequences, as was shown in the U...

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“…With the exception of Nocardia nova and Nocardia otitidiscaviarum, Nocardia species were not identified, nor were Tsukamurella or Gordonia species. Schulthess et al evaluated the Biotyper system (database v3.1.2.0) for identification of gram-positive bacilli (18 ). Using the manufacturer's interpretative criteria and an initial collection of 190 isolates, 85% and 87% of the grampositive bacilli studied were identified to the genus level with on-plate formic acid testing and formal extraction, respectively, compared to 72% with direct colony testing.…”

Section: Performance Of Maldi-tof Ms For Identification Of Aerobic Bamentioning

confidence: 99%

MALDI-TOF MS for the Diagnosis of Infectious Diseases

2015

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BACKGROUND:First introduced into clinical microbiology laboratories in Europe, MALDI-TOF MS is being rapidly embraced by laboratories around the globe. Although it has multiple applications, its widespread adoption in clinical microbiology relates to its use as an inexpensive, easy, fast, and accurate method for identification of grown bacteria and fungi based on automated analysis of the mass distribution of bacterial proteins.CONTENT: This review provides a historical perspective on this new technology. Modern applications in the clinical microbiology laboratory are reviewed with a focus on the most recent publications in the field. Identification of aerobic and anaerobic bacteria, mycobacteria, and fungi are discussed, as are applications for testing urine and positive blood culture bottles. The strengths and limitations of MALDI-TOF MS applications in clinical microbiology are also addressed.

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Evaluation of the Bruker MALDI Biotyper for Identification of Gram-Positive Rods: Development of a Diagnostic Algorithm for the Clinical Laboratory

Cited by 109 publications

References 32 publications

Use of the Bruker MALDI Biotyper for Identification of Molds in the Clinical Mycology Laboratory

Use of the Bruker MALDI Biotyper for Identification of Molds in the Clinical Mycology Laboratory

Identification of Highly Pathogenic Microorganisms by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry: Results of an Interlaboratory Ring Trial

MALDI-TOF MS for the Diagnosis of Infectious Diseases

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