Microbiological Evaluation of the New VITEK 2
            <i>Neisseria</i>
            -
            <i>Haemophilus</i>
            Identification Card

Valenza, Giuseppe; Ruoff, Claudia; Vogel, Ulrich; Frosch, Matthias; Abele‐Horn, Marianne

doi:10.1128/jcm.00953-07

Cited by 44 publications

(17 citation statements)

References 21 publications

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“…As data acquisition, spectral databases, and algorithms for spectral pattern matching evolve, performance is likely to improve and the specific failings of the present system might be remedied. With simple procedural optimizations, the rates of correct identification and misidentification (higher and lower, respectively) for even the most fastidious organisms are superior to those using biochemical methods (35), positioning MALDI-TOF to supplant them in the clinical microbiology laboratory.…”

Section: Discussionmentioning

confidence: 99%

Optimization of Routine Identification of Clinically Relevant Gram-Negative Bacteria by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and the Bruker Biotyper

Ford

Burnham

2013

J Clin Microbiol

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Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) might complement and one day replace phenotypic identification of bacteria in the clinical microbiology laboratory, but there is no consensus standard regarding the requirements for its validation prior to clinical use in the United States. The objective of this study was to assess the preanalytical variables influencing Gram-negative identification by use of the Bruker Biotyper MALDI-TOF MS system, including density of organism spotting on a stainless steel target plate and the direct overlay of organisms with formic acid. A heavy smear with formic acid overlay was either superior or equivalent to alternative smear conditions. Microbiological preanalytical variables were also assayed, such as culture medium, growth temperature, and use of serial subculture. Postanalytical analysis included the application of modified species-level identification acceptance criteria. Biotyper identifications were compared with those using traditional phenotypic methods, and discrepancies were resolved with 16S rRNA gene sequencing. Compared to the recommended score cutoffs of the manufacturer, the application of optimized Biotyper score cutoffs for species-level identification increased the rate of identification by 6.75% for the enteric Gram-negative bacteria and 4.25% for the nonfermenting Gramnegative bacteria. Various incubation temperatures, growth medium types, and repeat subcultures did not result in misidentification. We conclude that the Bruker MALDI Biotyper is a robust system for the identification of Gram-negative organisms in the clinical laboratory and that meaningful performance improvements can be made by implementing simple pre-and postanalytical techniques.M atrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) employs soft ionization to detect individual intact biomolecules within complex solutions. Practical use of MALDI-TOF has been facilitated by the development of matrices, such as ␣-cyano-4-hydroxycinnamic acid (1). While the potential for the identification of bacteria by their individual mass spectrometric "fingerprints" has long been appreciated (2), the adoption of MALDI-TOF MS in clinical microbiology laboratories in the United States has been hindered until recently by a lack of available platforms with databases of bacterial whole-cell MALDI-TOF reference spectra.Recent studies using the Bruker Biotyper MALDI-TOF MS platform have revealed that this system might correctly identify bacteria to the species level 95% of the time, with the remaining 5% comprising unidentified or erroneously identified isolates (3, 4). These studies invariably used Bruker's recommended scoring cutoffs (a Biotyper score of Ն2.0 for species-level identification and Ն1.7 for genus-level identification) to define the confidence with which a correct identification had been made. Alatoom and colleagues (5) noted that the preparatory extraction of the protein fraction of Gram-positive organisms was ne...

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Section: Discussionmentioning

confidence: 99%

Optimization of Routine Identification of Clinically Relevant Gram-Negative Bacteria by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and the Bruker Biotyper

Ford

Burnham

2013

J Clin Microbiol

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“…Phenotypic characteristics can be determined by conventional testing in single tubes (15,28,48,130) or by a number of semi-or fully automated systems (129,(131)(132)(133)(134)(135)(136)(137). The use of automated systems is feasible and cost-effective, and they usually perform well when challenged with strains of species that are included in their databases (135)(136)(137).…”

Section: Other Phenotypic Characterizationmentioning

confidence: 99%

Classification, Identification, and Clinical Significance of Haemophilus and Aggregatibacter Species with Host Specificity for Humans

2014

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SUMMARY The aim of this review is to provide a comprehensive update on the current classification and identification of Haemophilus and Aggregatibacter species with exclusive or predominant host specificity for humans. Haemophilus influenzae and some of the other Haemophilus species are commonly encountered in the clinical microbiology laboratory and demonstrate a wide range of pathogenicity, from life-threatening invasive disease to respiratory infections to a nonpathogenic, commensal lifestyle. New species of Haemophilus have been described ( Haemophilus pittmaniae and Haemophilus sputorum ), and the new genus Aggregatibacter was created to accommodate some former Haemophilus and Actinobacillus species ( Aggregatibacter aphrophilus , Aggregatibacter segnis , and Aggregatibacter actinomycetemcomitans ). Aggregatibacter species are now a dominant etiology of infective endocarditis caused by fastidious organisms (HACEK endocarditis), and A. aphrophilus has emerged as an important cause of brain abscesses. Correct identification of Haemophilus and Aggregatibacter species based on phenotypic characterization can be challenging. It has become clear that 15 to 20% of presumptive H. influenzae isolates from the respiratory tracts of healthy individuals do not belong to this species but represent nonhemolytic variants of Haemophilus haemolyticus . Due to the limited pathogenicity of H. haemolyticus , the proportion of misidentified strains may be lower in clinical samples, but even among invasive strains, a misidentification rate of 0.5 to 2% can be found. Several methods have been investigated for differentiation of H. influenzae from its less pathogenic relatives, but a simple method for reliable discrimination is not available. With the implementation of identification by matrix-assisted laser desorption ionization–time of flight mass spectrometry, the more rarely encountered species of Haemophilus and Aggregatibacter will increasingly be identified in clinical microbiology practice. However, identification of some strains will still be problematic, necessitating DNA sequencing of multiple housekeeping gene fragments or full-length 16S rRNA genes.

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“…The card has a database that includes 27 taxa of gram-negative fastidious bacteria and that maintains the predominance of Haemophilus and Neisseria species but also includes Actinobacillus, Campylobacter, Capnocytophaga, Cardiobacterium, Eikenella, Gardnerella, Kingella, Moraxella, Oligella, and Suttonella species. In a recently published investigation from one laboratory, 91% of strains included in the database were identified correctly without the need for additional tests (17). In the present investigation, the quality, reproducibility, and accuracy of this NH card were assessed in three large tertiary care clinical laboratories.…”

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confidence: 96%

Multicenter Evaluation of the New Vitek 2 Neisseria - Haemophilus Identification Card

et al. 2008

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The new Neisseria-Haemophilus identification (NH) card for Vitek 2 was compared with 16S rRNA gene sequencing (16S) as the reference method for accurate identification of Neisseria spp., Haemophilus spp., and other fastidious gram-negative bacteria. Testing was performed on the Vitek 2 XL system with modified software at three clinical trial laboratories. Reproducibility was determined with nine ATCC quality control strains tested 20 times over a minimum of 10 days at all three sites. A challenge set of 30 strains with known identifications and 371 recent fresh and frozen clinical isolates were also tested. Expected positive and negative biochemical reactions were also evaluated for substrate reproducibility. All microorganisms were tested on the NH card, and all clinical and stock isolates were saved for 16S testing. All reproducibility tests yielded expected results within a 95% confidence interval. For challenge microorganisms, there was 98% overall correct identification, including 8% low discrimination, 2% incorrect identification, and 0% unidentified. For clinical strains, there was 96.5% overall correct identification, including 10.2% low discrimination, 2.7% incorrect identification, and 0.8% unidentified. The 2.7% (10/371) of clinical isolates that gave an incorrect identification consisted of 7 isolates correct to genus and 3 strains incorrect to genus. There were an additional 27 strains (primarily Neisseria species) for which the 16S identification result was different from the NH card result. These were all unclaimed species by the system. The new NH card met all performance criteria within a 95% confidence interval compared to identification of clinical isolates by 16S.In the diagnostic clinical microbiology laboratory, rapid and accurate identification of bacterial pathogens is essential for prompt and appropriate management of infected patients. This is important for bacterial pathogens within the genera Haemophilus and Neisseria.The science has evolved over many years. Classical methods gave way to substrate-based identification of these microorganisms involving overnight and then shorter incubation. More recently molecularly based identification has started to change the landscape (2,5,7,8,12), but for most laboratories that lack such sophisticated technical capabilities, the ability to use either a manual or automated system that will give a high level of correct identifications is sufficient for most purposes.For identification of Haemophilus and Neisseria species, a variety of commercial methods have been available on the market for many years. For Neisseria species these have included Neisseria-Kwik, Gonogen, Gonochek II, RIM-N, API QuadFERM-Plus, Minitek, Identicult-Neisseria, and several others (1,6,16,18). All of these are based on colorimetric changes in miniaturized substrates, with either enzymatic or growth end points. The ability to identify and separate Haemophilus species from nonpathogenic Neisseria species, particularly those from the respiratory tract, then led to the addition ...

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Microbiological Evaluation of the New VITEK 2 Neisseria - Haemophilus Identification Card

Cited by 44 publications

References 21 publications

Optimization of Routine Identification of Clinically Relevant Gram-Negative Bacteria by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and the Bruker Biotyper

Optimization of Routine Identification of Clinically Relevant Gram-Negative Bacteria by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and the Bruker Biotyper

Classification, Identification, and Clinical Significance of Haemophilus and Aggregatibacter Species with Host Specificity for Humans

Multicenter Evaluation of the New Vitek 2 Neisseria - Haemophilus Identification Card

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