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

Bradley A Ford; Carey-Ann D Burnham

doi:10.1128/JCM.01803-12

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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

Journal article

Open access

Peer reviewed

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

Bradley A Ford and Carey-Ann D Burnham

Journal of clinical microbiology, Vol.51(5), pp.1412-1420

05/2013

DOI: 10.1128/JCM.01803-12

PMCID: PMC3647914

PMID: 23426923

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Abstract

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 Gram-negative 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.

DNA, Bacterial - genetics

Bacterial Typing Techniques

Base Sequence

Humans

RNA, Ribosomal, 16S - genetics

Gram-Negative Bacterial Infections - diagnosis

Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Gram-Negative Bacteria - genetics

Gram-Negative Bacteria - isolation & purification

Sequence Analysis, DNA

Gram-Negative Bacteria - classification

Details

Title: Subtitle: 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
Creators: Bradley A Ford - Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
Carey-Ann D Burnham
Resource Type: Journal article
Publication Details: Journal of clinical microbiology, Vol.51(5), pp.1412-1420
Publisher: United States
DOI: 10.1128/JCM.01803-12
PMID: 23426923
PMCID: PMC3647914
ISSN: 0095-1137
eISSN: 1098-660X
Language: English
Date published: 05/2013
Academic Unit: Pathology
Record Identifier: 9984047990102771

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